CN1749427A - Heat-resisting steel, heat treatment method for heat-resisting steel and high-temperature steam turbine rotor - Google Patents

Abstract

A kind of C of 0.25～0.35, Si of 0.15 or less, Mn of 0.2～0.8, Ni of 0.3～0.6, Cr of 1.6～1.9, V of 0.26～0.35, Mo of 0.6～0.9, A heat-resistant steel composed of W of 0.9 to 1.4, Ti of less than 0.01, N of 0.001 to 0.007, Mo and W/2 of 1.3 to 1.4 in total, and the balance of Fe and unavoidable impurities. After pyrothermal treatment, the heat-resistant steel has a bainitic single-phase structure composition that ensures 1.0 or more Fe, 0.8 to 0.9 Cr, 0.4 to 0.5 Mo, 0.3 to 0.5 W and 0.2 or more by weight percentage The V moved into the sediment, and the total amount of sediment was 3.5 or higher.

Description

Heat-resistant steel, heat treatment method of heat-resistant steel, and high-temperature steam turbine rotor

Cross References to Related Applications

This application is based on and claims priority from a prior Japanese Patent Application No. 2004-269947 filed on September 16, 2004; the entire contents of which are hereby incorporated by reference.

technical field

The present invention relates to a heat-resistant steel, and more particularly relates to a high-temperature steam turbine rotor material and a heat-resistant steel for a steam turbine with outstanding performance, a heat treatment method for the heat-resistant steel, and a high-temperature steam turbine rotor.

Background technique

As high-temperature component materials for thermal power generation equipment, low-alloy heat-resistant steel represented by 1Cr-1Mo-0.25V steel and high-Cr heat-resistant steel represented by 12Cr-1Mo-VNbN steel are widely used. However, in recent years, the use of high-Cr heat-resistant steels having outstanding high-temperature performance has been increased because thermal power plants are required to rapidly raise the steam temperature higher.

Meanwhile, since thermal power generation equipment has been required to have high efficiency and economical efficiency in recent years, it is desired to use inexpensive and high-performance heat-resistant steel as a component material.

Components constituting the central part of thermal power generation equipment are formed of large-sized materials, which necessitate requirements to be excellent in productivity and formability into desired shapes. Also, they are required to have material properties that are not damaged but remain uniform even when forming large parts. However, for example, the conventional heat-resistant steel containing the chemical composition disclosed in Japanese Patent No. 3,334,217 is poor in quenching performance when used as a large part, and can hardly exhibit the expected performance in the central part of the steel ingot having a large drum diameter . A heat-resistant steel containing the chemical composition disclosed in Japanese Patent No. 3,439,197 has considerable component precipitation when a large ingot is cast, and can hardly develop uniform material properties in the entire ingot. Heat-resistant steel has disadvantages including trade-offs such as poor economical efficiency when special dissolution is used to improve the uniformity of the ingot.

Conventional heat-resistant steels contain relatively large amounts of ferrite-forming elements such as Cr, Mo, and W as reinforcing elements, so the tendency to generate ferrite phase becomes high. In general, the ferrite phase generated in the bainite phase is formed by the chemical combination of the above-mentioned ferrite-forming elements and Fe. Therefore, these added elements as reinforcing elements are locally concentrated in the resulting ferrite, and have the disadvantage of reducing the content of elements in the bainite structure, which in particular causes a decrease in high-temperature strength. In addition, when the amount of ferrite phase produced in heat-resistant steel increases, the impact performance or toughness of the material may be greatly reduced.

Contents of the invention

According to one aspect of the present invention, there are provided a heat-resistant steel having a bainite single-phase structure that can be stably used in a high-temperature steam environment and has outstanding economic efficiency, a heat treatment method for the heat-resistant steel, and a high-temperature steam turbine rotor.

The heat-resistant steel of the present invention is composed of C of 0.25 to 0.35, Si of 0.15 or less, Mn of 0.2 to 0.8, Ni of 0.3 to 0.6, Cr of 1.6 to 1.9, V of 0.26 to 0.35, V of 0.6 to Mo of 0.9, W of 0.9 to 1.4, Ti of less than 0.01, N of 0.001 to 0.007, a total of 1.3 to 1.4 of Mo and W/2, and the balance of Fe and unavoidable impurities. After heat treatment, the heat-resistant steel is composed of a bainite single-phase structure, ensuring such as 1.0 or more Fe, 0.8-0.9 Cr, 0.4-0.5 Mo, 0.3-0.5 W and 0.2 or more by weight percentage Too much V moved into the precipitate, and the total amount of the precipitate was 3.5 or higher.

The heat-resistant steel of the present invention is composed of C of 0.25 to 0.35, Si of 0.15 or less, Mn of 0.2 to 0.8, Ni of 0.3 to 0.6, Cr of 1.6 to 1.9, V of 0.26 to 0.35, V of 0.6 to 0.9 of Mo, 0.9 to 1.4 of W, less than 0.01 of Ti, 1.3 to 1.4 of Mo and W/2 in total, and the balance of Fe and unavoidable impurities, wherein after tempering heat treatment, the heat resistant The steel is composed of a bainite single-phase structure, ensuring that 1.0 or more Fe, 0.8-0.9 Cr, 0.4-0.5 Mo, 0.3-0.5 W, and 0.2 or more V move into the precipitate by weight percentage, And the total amount of sediment is 3.5 or higher.

The heat-resistant steel of the present invention is composed of C of 0.25 to 0.35, Si of 0.15 or less, Mn of 0.2 to 0.8, Ni of 0.3 to 0.6, Cr of 1.6 to 1.9, V of 0.26 to 0.35, V of 0.6 to Mo of 0.9, W of 0.9 to 1.4, N of 0.001 to 0.007, a total of 1.3 to 1.4 of Mo and W/2 and the balance of Fe and unavoidable impurities, wherein after tempering heat treatment, the heat resistant The steel is composed of a bainite single-phase structure, ensuring that 1.0 or more Fe, 0.8-0.9 Cr, 0.4-0.5 Mo, 0.3-0.5 W, and 0.2 or more V move into the precipitate by weight percentage, And the total amount of sediment is 3.5 or higher.

According to the heat-resistant steel described above, the heat-resistant steel composed of a bainite single-phase structure can be formed by forming within the content range of the single component element. In this way, it is possible to provide a heat-resistant steel which is excellent in high-temperature performance, toughness, embrittlement performance, etc. and does not contain a ferrite phase or the like which greatly degrades the mechanical properties of the material when the generated amount increases. The constituent elements Ti and/or N described above may be replaced by Fe and C.

The heat treatment method that is used for the heat-resistant steel of the present invention comprises by weight percent by the C of 0.25～0.35, the Si of 0.15 or less, the Mn of 0.2～0.8, the Ni of 0.3～0.6, the Cr of 1.6～1.9, the Cr of 0.26～ V of 0.35, Mo of 0.6-0.9, W of 0.9-1.4, Ti of less than 0.01, N of 0.001-0.007, a total of 1.3-1.4 of Mo and W/2, and the balance of Fe and unavoidable impurities The composed steel ingot is heated to 980-1030°C, cooled so that the cooling rate of the center portion of the steel ingot becomes at least 20°C/h or more, and then subjected to tempering treatment.

The heat treatment method that is used for the heat-resistant steel of the present invention comprises by weight percent by the C of 0.25～0.35, the Si of 0.15 or less, the Mn of 0.2～0.8, the Ni of 0.3～0.6, the Cr of 1.6～1.9, the Cr of 0.26～ A steel ingot composed of 0.35 V, 0.6-0.9 Mo, 0.9-1.4 W, less than 0.01 Ti, a total of 1.3-1.4 Mo and W/2, and the balance of Fe and unavoidable impurities is heated to 980 ~1030°C, cooling so that the cooling rate of the center portion of the ingot becomes at least 20°C/h or more, and then performing tempering treatment.

The heat treatment method that is used for the heat-resistant steel of the present invention comprises by weight percent by the C of 0.25～0.35, the Si of 0.15 or less, the Mn of 0.2～0.8, the Ni of 0.3～0.6, the Cr of 1.6～1.9, the Cr of 0.26～ A steel ingot composed of 0.35 V, 0.6-0.9 Mo, 0.9-1.4 W, 0.001-0.007 N, a total of 1.3-1.4 Mo and W/2 and the balance of Fe and unavoidable impurities is heated to 980 ~1030°C, cooling so that the cooling rate of the center portion of the ingot becomes at least 20°C/h or more, and then performing tempering treatment.

According to the above-mentioned heat treatment method for heat-resistant steel, quenching is carried out even at a very low cooling rate of at least 20°C/h or more in the central part of the ingot without passing through, for example, a cooling medium such as water, oil or the like or blasting Forced cooling can also form a heat-resistant steel including a bainite single-phase structure without forming a ferrite phase.

The high-temperature steam turbine rotor of the present invention comprises C of 0.25 to 0.35, Si of 0.15 or less, Mn of 0.2 to 0.8, Ni of 0.3 to 0.6, Cr of 1.6 to 1.9, V of 0.26 to 0.35, and V of 0.6 by weight percentage. A heat-resistant steel consisting of Mo of ~0.9, W of 0.9-1.4, Ti of less than 0.01, N of 0.001-0.007, a total of 1.3-1.4 of Mo and W/2, and the balance of Fe and unavoidable impurities , wherein after the tempering heat treatment, the heat-resistant steel is composed of a bainite single-phase structure, ensuring 1.0 or more Fe, 0.8-0.9 Cr, 0.4-0.5 Mo, 0.3-0.5 W in percentage by weight And a V of 0.2 or more moved into the precipitate with a total amount of 3.5 or more in the precipitate.

The high-temperature steam turbine rotor of the present invention comprises C of 0.25 to 0.35, Si of 0.15 or less, Mn of 0.2 to 0.8, Ni of 0.3 to 0.6, Cr of 1.6 to 1.9, V of 0.26 to 0.35, and V of 0.6 by weight percentage. A heat-resistant steel composed of ~0.9 Mo, 0.9~1.4 W, less than 0.01 Ti, a total of 1.3~1.4 Mo and W/2, and the balance of Fe and unavoidable impurities. After that, the heat-resistant steel is composed of a bainite single-phase structure, ensuring 1.0 or more Fe, 0.8 to 0.9 Cr, 0.4 to 0.5 Mo, 0.3 to 0.5 W and 0.2 or more by weight percentage V moved into the sediment, and the total amount of sediment was 3.5 or higher.

The high-temperature steam turbine rotor of the present invention comprises C of 0.25 to 0.35, Si of 0.15 or less, Mn of 0.2 to 0.8, Ni of 0.3 to 0.6, Cr of 1.6 to 1.9, V of 0.26 to 0.35, and V of 0.6 by weight percentage. ~0.9 Mo, 0.9~1.4 W, 0.001~0.007 N, a total of 1.3~1.4 Mo and W/2, and the balance of Fe and unavoidable impurities. After that, the heat-resistant steel consists of a bainite single-phase structure, ensuring 1.0 or more Fe, 0.8-0.9 Cr, 0.4-0.5 Mo, 0.3-0.5 W, and 0.2 or more V by weight percentage Remove the sediment with a total sediment of 3.5 or higher.

According to the high-temperature steam turbine rotor described above, a high-temperature steam turbine rotor including a bainitic single-phase structure can be formed by forming within the content range of the single component elements described above. Thus, it is possible to provide a high-temperature steam turbine rotor excellent in high-temperature performance, toughness, embrittlement performance, etc., free of a ferrite phase or the like which would greatly degrade the mechanical properties of the material if produced in an increased amount. The constituent elements Ti and/or N described above may be replaced by Fe and C. When the high temperature turbine rotor is in smooth operation, the total amount of deposits after operating at the highest temperature corresponding to 100,000 hours in the vicinity of the portion of the high temperature turbine rotor exposed to steam is ensured to be 2.8% or higher. The maximum temperature of the steam is about 540-580°C during smooth operation.

The high temperature steam turbine rotor is a high pressure rotor, a medium pressure rotor or a high and medium pressure rotor. It is at the exhaust temperature of 300°C or higher at the final stage outlet of the high pressure rotor or the high pressure part of the high and medium pressure rotor and at the discharge temperature of 200°C or higher at the final stage outlet of the medium pressure rotor or the medium pressure part of the high and medium pressure rotor. The rotor of a steam turbine operating at air temperature. The exhaust steam is introduced into a separately configured boiler or low-pressure turbine.

Detailed ways

One embodiment of the present invention will be described below.

First, the reason why the ranges of the individual components of the alloy used in the present invention are limited is described. Unless otherwise specified, the "%" unit of measurement expressing ingredients in the following description means "% by weight".

(1) C (carbon)

C is an inevitable element as a constituent element of various carbides contributing to dispersion strengthening and ensuring quenchability. If its content is less than 0.25%, the above-mentioned effects are small. If its content exceeds 0.35%, it will accelerate the grain coarsening of carbides, and the tendency of precipitation when the steel ingot solidifies will also be strengthened. Therefore, it is determined that the C content is in the range of 0.25-0.35%, more preferably in the range of 0.27-0.33%.

(2) Si (silicon)

Si is useful as a deoxidizing element as well as improving resistance to steam oxidation. However, if its content is high, toughness decreases and embrittlement accelerates. Therefore, it is desirable that its content be as low as possible. If the Si content exceeds 0.15%, the above-mentioned favorable properties are greatly reduced. Therefore, it was determined that the Si content was not more than 0.15% (excluding 0). The content of Si is preferably not more than 0.1%.

(3) Mn (manganese)

Mn is a useful element as a desulfurization element, but if its content is less than 0.2%, its desulfurization effect is not obvious, and if its addition exceeds 0.8%, its creep strength will decrease. Therefore, it is confirmed that the content of Mn is in the range of 0.2 to 0.8%, more preferably in the range of 0.4 to 0.8%.

(4) Cr (chromium)

Cr is an effective element for oxidation resistance and corrosion resistance and is also indispensable as a constituent element contributing to enhancement of precipitated carbonitrides. In the heat-resistant steel according to the present invention, Cr is also useful as an effective element for improving toughness. If the Cr content is less than 1.6%, the amount of Cr incorporated into the carbonitride after the tempering heat treatment is small, so that the high temperature stability of the carbonitride cannot be ensured. If the Cr content exceeds 1.9%, the temper softening resistance decreases, the desired normal temperature strength cannot be ensured, and the creep strength decreases. Therefore, it was determined that the Cr content was in the range of 1.6 to 1.9%.

(5) V (vanadium)

V contributes to solid solution strengthening and the formation of fine carbonitrides. If the V content is 0.26% or more, enough fine precipitates are deposited to inhibit the recovery of the bainite structure, but if it exceeds 0.35%, the toughness decreases and the carbonitride grains Coarsening is also accelerated. Therefore, it is determined that the content of V is in the range of 0.26 to 0.35%.

(6) W (tungsten)

W contributes to solid solution strengthening and dispersion strengthening of the bainite structure by becoming a constituent element of carbonitrides. Especially when W and Mo are added together, the high temperature stability of the precipitate can be significantly improved. W enters the precipitate from the bainite structure as a function of heating time at a high temperature for a long time. Therefore, it is necessary to set the W content to 0.9% or more to maintain a W content that contributes to high solid solution strengthening over a long period of time. However, if the W content exceeds 1.4%, the toughness decreases, ferrite tends to be generated, and the precipitation tendency of components in large steel ingots increases. Therefore, it is confirmed that the content of W is in the range of 0.9 to 1.4%, more preferably in the range of 0.9 to 1.2%.

(7) Mo (molybdenum)

Mo contributes to solid solution strengthening and dispersion strengthening by becoming a constituent element of carbonitrides. Especially when Mo and W are added together, the high temperature stability of the precipitate can be significantly improved. Mo enters the precipitate from the bainite structure as a function of heating time at a high temperature for a long time. Therefore, it is necessary to set the content of Mo to 0.6% or more to maintain the content of Mo that contributes to high solid solution strengthening for a long time. However, if the Mo content exceeds 0.9%, the toughness decreases, ferrite tends to be generated, and the precipitation tendency of components in large steel ingots increases. Therefore, it is confirmed that the content of Mo is in the range of 0.6 to 0.9%, more preferably in the range of 0.7 to 0.9%.

(8) N (nitrogen)

N forms nitrides or carbonitrides to contribute to dispersion strengthening. In addition, N remaining in the bainite structure also contributes to solid solution strengthening, but if the content of N is less than 0.001%, the above effect is not obvious. On the other hand, if the N content exceeds 0.007%, the grain coarsening of nitrides or carbonitrides is accelerated, and the creep strength is lowered. Therefore, it was determined that the content of N was in the range of 0.001 to 0.007%. For the formation of carbonitrides in the heat-resistant steel of the present invention, N can be replaced by increasing the C content within the range of the C content. Fe can also be used in place of N.

(9) Ti (titanium)

Ti is useful as a deoxidizing element. If the content of Ti is less than 0.01%, it can exert a deoxidizing effect, and the remaining Ti forms a solid solution. However, if the Ti content exceeds 0.01%, the generation of non-solid solution coarsened Ti carbonitrides increases, resulting in a decrease in toughness or weakening of the notch. Therefore, it was determined that the content of Ti was less than 0.01% (excluding 0). The inclusion of Ti in the above content allows the amount of O (oxygen) in the steel ingot to be reduced by deoxidation, and also prevents the formation of oxides at the time of steel ingot production. Ti can be replaced by increasing the C content within the range of the C content. And Fe can also be used instead of Ti.

(10) Ni (nickel)

Ni improves hardenability and toughness and has an effect of suppressing ferrite generation. This effect can be observed when the Ni content is 0.35 or higher. However, if the Ni content exceeds 0.6%, the creep strength decreases. Therefore, it was determined that the content of Ni was in the range of 0.3 to 0.6%.

It is desirable to minimize the incidental inclusion of impurities when adding the above-described components as well as the main component Fe. Inevitable impurities in the heat-resistant steel of the present invention include P (phosphorus), S (sulfur), Cu (copper), Al (aluminum), As (arsenic), Sn (tin), Sb (antimony) and O (oxygen) . These impurities can cause embrittlement when the heat-resistant steel is heated at high temperature for a long time. As far as those unavoidable impurity elements are concerned, it is desirable to reduce their content to zero as much as possible, especially less than 0.015% of P, less than 0.005% of S, less than 0.1% of Cu, low 0.01% Al, less than 0.005% As, 0.005% Sn, less than 0.005% Sb and less than 20ppm oxygen.

Next, the reason why the total amount of Mo and W/2 is limited to 1.3 to 1.4 will be described.

In the heat-resistant steel of the present invention, W and Mo each have an effect as described in (6) and (7) above. When they are added together, the increase in creep strength is better than when they are added separately, however, the precipitation tendency of light element components is greatly increased when making large ingots. It is therefore necessary to limit the amount of W and Mo added together to develop the desired creep strength and avoid precipitation. In view of doing so, it is generally desirable to use an index called Mo equivalent (total amount of Mo and W/2 (weight %)). For the heat-resistant steel of the present invention, when the Mo equivalent value is less than 1.3, the creep strength decreases, and if the Mo equivalent value exceeds 1.4, the precipitation of components becomes considerable at the time of large ingot production. Therefore, the Mo equivalent value (total amount (weight %) of Mo and W/2) was determined to be 1.3 to 1.4.

Then, why 1.0 or more of Fe, 0.8 to 0.9 of Cr, 0.4 to 0.5 of Mo, 0.3 to 0.5 of W, and 0.2 The reason why V or more is contained in the sediment and the total amount of the sediment is ensured is 3.5 or higher.

The heat-resistant steel of the present invention is strengthened by solid-solution strengthening of the bainite structure and precipitation of carbonitrides. Carbonitrides are deliberately precipitated by tempering heat treatment, and the precipitates in the heat-resistant steel of the present invention are M, VC, R type, M, RC type, M, QC type and MC type four types. M refers to a metallic element. M, VC, R type and M, RC type M is mainly Fe and Cr, and may also contain Mo, W and so on. M, M in the QC type is mainly Mo and W, and may also contain V in addition. M in the MC type is mainly V, and may additionally contain Mo and W.

The reason why the above Fe, Cr, Mo, W and V are limited to the respective composition ranges will be described below. Unless otherwise specified, the unit of measurement expressing "%" of ingredients in the following description means "% by weight".

The amount of precipitate was measured and identified as follows. The test sample is placed in a mixed liquid of methanol, acetylacetone and tetramethylammonium chloride, and the bainite structure is dissolved by electrolysis. After filtration, the resulting residue was washed and weighed. The value determined from the ratio of the weight before and after dissolution was used. In addition, the recovered residue is identified by X-ray analysis or the like to identify the type of precipitate.

(11) Fe (iron)

Fe in the precipitate is the main constituent element of M, VC, R type and M, RC type precipitates, which contributes to dispersion strengthening. If the amount of Fe entering the precipitate after the tempering heat treatment is less than 1.0%, the amount of the precipitate is small and the dispersion strengthening effect is insufficient. In order to develop creep strength, it is effective to use the time-dependent transformation after precipitation of M, RC type precipitates after tempering heat treatment, however, if the movement of Fe is less than 1.0%, the precipitation of M, RC type precipitates The amount is small, so no increase in creep strength can be expected by this method. Therefore, the content of Fe in the precipitate after the tempering heat treatment was determined to be 1.0% or more.

(12) Cr (chromium)

Cr in the precipitate is the main component element of M, VC, R type and M, RC type precipitate, which contributes to dispersion strengthening. Cr replaces part of Fe in the precipitate, so it also has the effect of improving the stability of the precipitate. If the amount of Cr entering the precipitate after the tempering heat treatment is less than 0.8%, the amount of the precipitate is small, so that the dispersion strengthening effect is insufficient. And if the amount of Cr entering the precipitate after the tempering heat treatment exceeds 0.9%, it will cause the disappearance of Fe, RC type precipitates during the tempering heat treatment, so that the time lag effect described in (11) above cannot be brought into play. Therefore, the content of Cr in the precipitate after the tempering heat treatment is determined to be in the range of 0.8-0.9%.

(13)W (tungsten)

W in the precipitate is the main constituent element of M, QC type precipitate, which contributes to dispersion strengthening. W replaces a part of M, VC, R type, M, RC type and MC type precipitates, so it greatly improves the high temperature stability of the precipitates. If the amount of W incorporated into the precipitate after the tempering heat treatment is less than 0.3%, the stability of the precipitate will be low, and the desired creep strength will not be exhibited. However, if the amount of W entering the precipitate after tempering heat treatment exceeds 0.5%, the amount of solid solution of W in the bainite structure will decrease, thereby reducing the amount of solid solution strengthening at high temperature. Therefore, the W content in the precipitate after the tempering heat treatment is determined to be in the range of 0.3-0.5%.

(14) Mo (molybdenum)

Mo in the precipitate is the main component element of the M, QC type precipitate, which contributes to dispersion strengthening. Mo replaces part of M, VC, R type, M, RC type and MC type precipitates, thus greatly improving the high temperature stability of the precipitates. If the amount of Mo entering the precipitate after the tempering heat treatment is less than 0.4%, the stability of the precipitate is low, so that the desired creep strength cannot be exhibited. However, if the amount of Mo entering the precipitate after tempering heat treatment exceeds 0.5%, the solid solution amount of Mo in the bainite structure will decrease, thereby reducing the amount of solid solution strengthening at high temperature. Therefore, the content of Mo in the precipitate after the tempering heat treatment is determined to be in the range of 0.4-0.5%.

(15) V (vanadium)

V in the precipitate is the main constituent element of the fine MC-type precipitate, which contributes to dispersion strengthening. v replaces part of M, VC, R type, M, RC type and M, QC type precipitate, thus greatly improving the high temperature stability of the precipitate. If the amount of V entering the precipitate after the tempering heat treatment is less than 0.2%, the amount of MC-type precipitates will decrease, and the stability of other precipitates will become low. Therefore, the content of V in the precipitate after the tempering heat treatment was determined to be 0.2% or more.

For the fine and uniform dispersion of the precipitate mainly composed of the above five elements of (11) to (15) and C, N, etc. by tempering heat treatment, the total amount of the precipitate is required to be 3.5% or more many. If the total amount is less than 3.5%, the strength characteristics and the high-temperature stability of the precipitate are reduced as described in (11) to (15) above. Therefore, the total amount of precipitates after the tempering heat treatment was determined to be 3.5% or more.

Next, it is described why after tempering heat treatment of a high-temperature steam turbine rotor formed of a heat-resistant steel composed of constituent elements within the range of (1) to (10) above, even after operation equivalent to 100,000 hours, exposure to stable When the total amount of deposits near the part of the steam at the highest temperature during operation is reduced after tempering heat treatment, it is preferable to keep the total amount of deposits (3.5%) in the above (11) to (15) within 2.8% or more of the causes.

The heat-resistant steel formed into the high-temperature steam turbine rotor of the present invention is different from ordinary heat-resistant steel, and the solid solution and precipitation of carbonitrides change with time during operation, resulting in outstanding high-temperature performance. Mo and W in the supersaturated solution state in heat-resistant steel mainly enter M, QC type precipitates and MC type precipitates with time to improve their high temperature stability, and M, RC type containing Fe as the main component element The precipitates are transformed over time into M, VC, R type precipitates which are more stable than those containing Cr as the main component element to maintain the creep strength. In particular, the latter includes the dissolution of Fe in M, RC type precipitates which are largely precipitated by tempering heat treatment, so that the total amount of precipitates is reduced compared to that after tempering heat treatment. Residual M, RC type precipitates have the effect of maintaining creep strength, but if the total amount of precipitates is less than 2.8%, M, RC type precipitates will be completely eliminated, so that the dispersion strengthening effect will decrease rapidly. Therefore, the total amount of deposits was determined to be 2.8% or more after running for an equivalent of 100,000 hours.

Precipitates deposited in heat-resistant steel formed into a high-temperature steam turbine rotor are different in the amount of precipitation depending on their type, and their amount of precipitation is variable over time depending on the operation of the high-temperature steam turbine rotor, but No new types of deposits were deposited when running. The maximum temperature of the steam during smooth operation is in the range of about 540-580°C.

Next, the reason why the particle size of prior austenite is preferably 100 μm or smaller on average will be described.

Prior austenite particle size has a greater influence on the individual mechanical properties. If it exceeds 100 µm, ductility decreases, cracks tend to occur at grain boundaries, and notch creep strength and toughness decrease. Therefore, the grain size of prior austenite is determined to be 100 µm or less on average.

The particle size is finally determined depending on the heating temperature during quenching. For the heat-resistant steel of the present invention, a heating temperature of 980 to 1030°C is desirable. If the heating temperature is lower than 980°C, a sufficient quenching effect cannot be obtained, and desired mechanical properties cannot be exhibited. On the other hand, if the heating temperature exceeds 1030°C, the particles will obviously become coarser. Performance decreases significantly with grain coarsening as described above.

The heat-resistant steel and high-temperature steam turbine rotor of the present invention contain the above-mentioned elements (1) to (10) within the specified range, the Mo equivalent value is within the specified range, and the prior austenite particle size is 100 μm or more on average. smaller. Also, the elements described in (11) and (12) above are contained in the precipitate in the specified range. After operation equivalent to 100,000 hours, the total amount of deposits can be ensured at a specified value or more near the portion of the high-temperature steam turbine rotor exposed to steam at the highest temperature during smooth operation, and the desired mechanical performance can be exerted accordingly performance.

Like the heat-resistant steel of the present invention containing ferrite-forming elements such as Cr, Mo, W, V, etc., ferrite may be generated in the metal structure depending on the addition amount of individual elements. These elements are concentrated in the ferrite of the low-alloy steel, so that the effects of the above-mentioned elements cannot be fully exerted. Therefore, it was determined that the heat-resistant steel of the present invention has an additional range of individual additive elements ((1) to (10)) in order to have a bainite single-phase structure.

The ferrite phase may be generated depending on the heating temperature during production or the cooling conditions after heating. Particularly where heating and cooling are repeated during the manufacturing process and where steam turbine rotors have large material dimensions, ferrite phases develop depending on the cooling rate, for example during hardening. In other words, the ferrite phase has characteristics that arise when exposed to a specified temperature range for a specified time. For example, if the cooling rate during quenching is low, it will pass through the generation zone during the cooling phase. As a result, a structure with a ferrite phase generated in the bainite structure is obtained, thereby degrading performance.

Even when carbonitrides are deposited in ferrite, the performance is lowered compared with the bainite single-phase structure, and the component concentration and structure inevitably become uneven. Therefore, in the manufacture of heat-resistant steels, the adjustment of the cooling rate and the acquisition of the bainite single-phase structure are noteworthy in order to avoid the generation zone during quenching.

It is nevertheless possible to provide heat-resistant steel and high-temperature steam turbine rotors having a bainite single-phase structure having a bainite single-phase structure with composition ranges according to the present invention and having good mechanical properties at high temperatures without limiting the cooling rate. Furthermore, according to the heat-resistant steel and the high-temperature steam turbine rotor of the present invention, stable operation can be performed in a high-temperature steam environment, and it is also good in terms of economical efficiency.

Embodiments of the present invention will be described below.

(first implementation)

It will be described that the heat-resistant steel according to one embodiment of the present invention has excellent properties. Sample steels in the first embodiment were produced by dissolving about 30 kg of material having the chemical composition range of the present invention, casting, hot forging ingots, annealing, normalizing and quenching and tempering. After normalization, quenching is carried out on the ingot at 980-1030°C, so that the cooling rate at the center of the ingot is approximately 20-80°C/h.

Table 1 lists the chemical composition of the fabricated sample steels. Among the sample steels shown in Table 1, steel types P1 to P14 are heat-resistant steels containing components in accordance with the scope of the present invention. On the other hand, steel types C1 to C6 are heat-resistant steels containing chemical components outside the scope of the present invention, and are comparative examples. Table 1 also lists the residual amount of oxygen for each steel type. The values in Table 1 are in percent by weight.

As shown in Table 1, the residual amount of oxygen in the sample steel containing Ti was at most 10 ppm. This value is lower than the residual amount of oxygen in the sample steel without Ti, which indicates that the deoxidation by Ti addition works effectively. Steel type C2 has a deoxidizing effect but produces Ti carbonitrides in a non-solid solution state.

The steel type shown in Table 1 is adjusted so that it has a 0.02% yield stress of about 660-690 MPa at normal temperature suitable for the steam turbine rotor shown in Table 2.

For each steel type, notched test pieces for a pendulum impact test according to JIS Z2202 having a thickness of 2 mm and a V-shaped notch were prepared, and the pendulum impact test was performed using these test pieces. The test results are shown in Table 2. Table 2 also lists the measurement results of the rupture time of the creep rupture test under the conditions of 600°C and 196MPa.

The steel types P1-P14 of the embodiments within the chemical composition range of the present invention have impact absorption energy of 50-55J at 20°C. However, the steel types C1-C6 of the comparative example have an impact absorbed energy of at most 40J at 20°C, which is generally lower than that of the embodiment.

For each steel of the steel types P1 to P14 of the embodiment, the rupture time in the creep rupture test performed under the conditions of 600° C. and 196 MPa was about 1850 hours at the shortest. On the other hand, the creep rupture time of the steel types C1-C6 of the comparative example is 800-1530 hours.

Among steel types of Comparative Example, steel type C1, steel type C3, and steel type C5 having relatively long fracture times had impact absorbed energy at 20°C significantly lower than that of each steel type of the embodiment. Creep rupture time when the Mo equivalent value (total amount of Mo and W/2 (weight %)) is lower than 1.3 as steel type C4 has and when the Mo equivalent value exceeds 1.4 as steel type C5 has Obviously short. In addition, even if the Mo equivalent is in the range of 1.3 to 1.4, if the addition of other elements is not within the chemical composition range of the present invention, the creep rupture time is short and the impact absorption energy is also low.

From the above, it can be found that when adjusted to a yield stress of 0.02% at the same normal temperature, the heat-resistant steel of the embodiment has an extremely high performance compared with the heat-resistant steel of the comparative example containing the added elements in an amount outside the composition range of the present invention. Good values for impact absorbed energy and creep time to rupture. Moreover, it can also be seen that the addition of Ti reduces the amount of residual oxygen in the ingot.

Table 1 steel type C Si mn Ni Cr V W Mo Ti N O(ppm) Fe Mo+W/2 Example P1 0.27 0.05 0.31 0.35 1.78 0.28 1.16 0.75 0.007 0.006 9 margin 1.330 P2 0.26 0.06 0.29 0.35 1.62 0.29 1.38 0.66 0.002 0.006 8 margin 1.350 P3 0.27 0.05 0.33 0.38 1.85 0.35 0.91 0.86 0.008 0.005 9 margin 1.315 P4 0.31 0.09 0.59 0.42 1.72 0.31 1.01 0.88 0.003 0.005 9 margin 1.385 P5 0.32 0.12 0.55 0.32 1.67 0.30 1.28 0.73 0.002 0.005 10 margin 1.370 P6 0.31 0.05 0.61 0.31 1.88 0.34 0.97 0.89 0.003 - 8 margin 1.375 P7 0.34 0.04 0.78 0.48 1.82 0.34 1.37 0.64 0.001 - 7 margin 1.325 P8 0.31 0.07 0.72 0.54 1.70 0.31 1.22 0.71 0.002 0.004 9 margin 1.320 P9 0.30 0.05 0.21 0.36 1.75 0.26 1.21 0.73 0.005 0.006 10 margin 1.335 P10 0.31 0.06 0.55 0.52 1.85 0.35 1.36 0.63 - 0.007 15 margin 1.310 P11 0.29 0.06 0.59 0.37 1.72 0.32 1.39 0.62 - 0.003 14 margin 1.315 P12 0.29 0.07 0.60 0.31 1.61 0.34 1.09 0.82 - 0.005 16 margin 1.365 P13 0.33 0.09 0.45 0.42 1.74 0.29 0.92 0.85 - - 12 margin 1.310 P14 0.33 0.06 0.52 0.39 1.65 0.27 1.31 0.74 - - 14 margin 1.395 CE ^* C1 0.24 0.05 0.68 0.44 1.83 0.27 0.67 1.02 - 0.004 15 margin 1.355 C2 0.28 0.17 0.51 0.53 1.79 0.28 1.52 0.55 0.009 - 9 margin 1.310 C3 0.30 0.05 0.59 0.35 1.15 0.28 - 1.33 - 0.003 16 margin 1.330 C4 0.05 0.19 0.49 0.02 2.23 0.23 1.58 0.12 - 0.008 14 margin 0.910 C5 0.25 0.07 0.82 0.84 1.25 0.25 0.42 1.25 - - 13 margin 1.460 C6 0.36 0.05 0.17 0.25 1.85 0.33 1.36 0.65 - 0.002 16 margin 1.330

^* CE: Comparative example

Table 2 steel type 0.02% yield stress at room temperature (MPa) Creep rupture time at 600℃-196Mpa (h) Absorbed energy at 20°C (J) Example P1 675 2178 55 P2 670 1942 52 P3 690 2054 54 P4 665 1905 53 P5 670 2008 50 P6 685 2265 50 P7 670 1895 55 P8 673 1854 50 P9 669 2058 50 P10 680 1980 52 P11 668 2057 50 P12 670 2237 50 P13 690 1878 52 P14 680 1968 50 comparative example C1 664 1527 12 C2 674 927 18 C3 665 1347 12 C4 658 812 40 C5 660 1280 25 C6 668 983 31

(second implementation)

It will be described that when tempering heat treatment is performed on heat-resistant steel containing the chemical composition range of the present invention, it is desirable to adjust it to a state that ensures a specified amount of precipitation.

In the second embodiment, the steel types P1, P6, P11 and P14 shown in Table 1 were quenched from 990°C so that the cooling rate at the center of the sample steel was approximately 20 to 80 °C/h, and tempering heat treatment is carried out at 630-730 °C.

Table 3 lists the contents (% by weight) of Fe, Cr, Mo, W, and V among the elements contained in the precipitates and the total amount (% by weight) of the precipitates after the tempering heat treatment of the sample steels. Table 3 also lists the measured results of the rupture time of the creep rupture test on the sample steel under the conditions of 600°C and 196MPa.

From the measurement results shown in Table 3, it can be seen that the content of individual elements contained in the precipitate after the tempering heat treatment of each steel type shown in the comparative example is not above the above-mentioned content of elements contained in the precipitate of the present invention. Within the range and when the total amount of precipitates is less than the range of the total amount of precipitates of the present invention (3.5% by weight or more), the creep rupture time becomes considerably shorter.

Meanwhile, it can be seen that the heat-resistant steel (embodiment) which reaches the content of the elements contained in the precipitate of the present invention and has the total amount of the precipitate not less than the total amount of the precipitate of the present invention (3.5% by weight or more) exhibits Excellent creep rupture properties. As assumed from the results of steel type P1, steel type P6, steel type P11, and steel type P14 in Table 2, in each steel type, the heat-resistant steel shown in the embodiment can not only ensure creep rupture performance but also Able to ensure sufficient impact absorption energy.

table 3 steel type Content in sediment after tempering heat treatment (Wt%) The total amount of sediment (Wt%) 600℃-196MPa creep rupture time (h) Fe Cr Mo W V P1 E. 1.27 0.85 0.46 0.36 0.26 3.77 2065 E. 1.54 0.85 0.42 0.42 0.26 3.89 2178 CE 0.95 0.83 0.34 0.28 0.24 3.34 1684 P6 E. 1.67 0.86 0.45 0.41 0.29 4.08 2084 E. 1.90 0.86 0.47 0.47 0.29 4.16 2265 CE 0.92 0.77 0.37 0.28 0.23 3.42 1551 P11 E. 1.85 0.82 0.44 0.45 0.27 4.05 2057 CE 1.43 0.92 0.52 0.53 0.27 3.96 1478 P14 E. 1.95 0.82 0.43 0.39 0.25 3.65 1968 E. 1.29 0.84 0.55 0.51 0.24 4.23 1069 CE 0.63 0.57 0.24 0.21 0.18 2.05 976

E=Example; CE=Comparative Example

(third implementation)

It will be described that when heat-resistant steels within the chemical composition range of the present invention are subjected to tempering heat treatment, they are adjusted to a state in which a specified amount of precipitation is ensured, and it is desired to be exposed to a specified temperature after operating for 100,000 hours equivalent to high temperature The total amount of sediment near the steam portion was ensured to be 2.8% by weight or higher.

In a third embodiment, the total amount of precipitates shown in Table 1 after the tempering heat treatment meets the content range of the elements contained in the precipitates of the present invention, and the total amount of precipitates is not less than the total amount of the precipitates of the present invention ( 3.5% by weight or more) or more heat-resistant steels of steel type P2, steel type P7, steel type P10, and steel type P13 were determined as sample steels. Also, heating the sample steel at a temperature in the range of 550 to 600° C. corresponds to 100,000 hours.

Table 4 lists the measurement results of the total amount of precipitates after tempering heat treatment and the total amount of precipitates after heating equivalent to 100,000 hours, and the measurement results of the rupture time obtained from the creep rupture test under the conditions of 600°C and 196MPa.

As can be seen from the measurement results shown in Table 4, when the total amount of precipitates after heating exceeds 2.8% by weight (embodiment column), the creep rupture time is 1500 hours or more, compared to the steel type shown in Table 2 The creep rupture time of P1 to P14 ensures at least 80% of the rupture time or more. And when the total amount of precipitate after heating is lower than 2.8% (comparative example column), the creep rupture time is about 700～825 hours, and the rupture time is only about 700～825 hours of the steel type P1～P14 creep rupture time shown in table 2 40%.

As can be seen from the above, when the heat-resistant steel within the chemical composition range of the present invention is subjected to tempering heat treatment, the elements described in (11) to (12) are contained in the precipitate in the specified range, and when in For example, heating at a high temperature of 550 to 600° C. corresponds to 100,000 hours and if the total amount of precipitates becomes 2.8% by weight or higher after that, a relatively long period of time can be obtained compared with the comparative example that does not reach that total amount of precipitates. creep rupture time.

Table 4 steel type The total amount of precipitate after tempering heat treatment (Wt%) Example comparative example The total amount of precipitate after heating (Wt%) 600℃-196MPa creep rupture time (h) The total amount of precipitate after heating (Wt%) 600℃-196MPa creep rupture time (h) P2 3.87 2.93 1624 2.76 825 P7 3.71 2.86 1520 2.61 811 P10 4.02 3.22 1648 2.35 703 P13 4.18 3.71 1585 2.73 796

(the fourth implementation)

It will be described that the heat-resistant steel within the chemical composition range of the present invention is suitable for the production of a steel ingot having small composition concentration precipitation and uniformity.

According to the fourth embodiment, it is assumed that 60 tons or more of steel ingots having chemical compositions as shown in Table 1 of steel type P6, steel type P12, steel type C2 and steel type C6 are manufactured, and the tendency of precipitation is numerically simulated .

According to the numerical simulation, the concentration of components in the height direction of the center portion of the ingot after solidification of an ingot manufactured by using a mold having a value obtained by dividing the diameter of the mold at the time of casting by the height of the mold of about 1.5 was analyzed.

Table 5 lists the analysis results of the component concentrations of the lightest element C and the heaviest element W in those formed into the above steel types. The values in Table 5 are values obtained by dividing the component concentrations of the molten metal by the component concentrations of the individual parts of the steel ingot. Also, the distance of 100% from the bottom of the ingot refers to the top of the ingot.

From the analysis results shown in Table 5, it can be seen that the concentration ratio of the lightest element C in steel type P6 and steel type P12 is in the range of 0.93 to 1.15, while the heaviest element W is in the steel type P6 and steel type P12 The concentration ratio is about 1.0. At the same time, it can be seen that the concentration ratio of C in steel types C2 and C6 becomes higher toward the tail of the ingot and considerable component precipitation occurs.

From the above results, it can be seen that the chemical composition range of the present invention is suitable for the manufacture of a steel ingot with small component concentration precipitation and uniformity.

table 5 steel type element Distance from the bottom of the ingot 5% 30% 50% 80% 100% P6 C 0.94 0.97 1.00 1.00 1.12 W 1.03 1.02 1.02 1.02 1.03 P12 C 0.93 0.97 1.03 1.09 1.15 W 1.02 1.04 1.00 1.03 1.04 C2 C 0.93 0.98 1.03 1.26 1.36 W 1.07 1.04 1.03 1.03 1.04 C6 C 0.91 0.94 1.15 1.21 1.35 W 1.08 1.08 1.07 1.05 1.05

(fifth implementation)

It will be described why it is desirable to adjust the prior-austenite grain size of the heat-resistant steel having the chemical composition range of the present invention to 100 μm or less on average.

According to the fifth embodiment, steel types P3, P7, P12, and P13 shown in Table 1 were used as sample steels. The particle diameters of the sample steels were adjusted by hot working, and then adjusted to a 0.02% yield stress of about 660 to 690 MPa at room temperature suitable for a steam turbine rotor.

The grain size of the sample steel was measured by the test method described in JIS G 0551. And, the reduction of area at 300°C was measured according to the tensile test method described in JIS Z 2241. In addition, it was measured whether the notched creep rupture strength obtained from the creep rupture test at 300°C was increased or decreased compared to the lubricating material.

Table 6 lists the results of the above measurements.

From the measurement results shown in Table 6, it can be seen that if the original austenite grain size does not exceed 100 μm (embodiment), 50% or more of the tensile reduction of area and notch strength can be exerted, but if the original austenite When the grain size of the tenite exceeds 100 μm (comparative example), the tensile reduction of area decreases sharply, and the notch is also weakened.

As can be seen from the above, excellent tensile characteristics and creep rupture properties can be exerted by adjusting the heat-resistant steel within the chemical composition range of the present invention to a specified deposition state and adjusting the grain size to 100 μm or less.

Table 6 steel type Particle size (μm) Tensile reduction of area at 300°C Notch Creep P3 E. 60 55 Notch strengthening E. 95 50 Notch strengthening CE 110 28 Gap weakening P7 E. 55 57 Notch strengthening E. 80 52 Notch strengthening CE 110 28 Gap weakening P12 E. 70 57 Notch strengthening CE 105 26 Gap weakening P13 E. 85 55 Notch strengthening CE 120 25 Gap weakening

E = Example CE = Comparative Example

The present invention is not limited to the above-mentioned embodiments, and various modifications and changes can be made within the technical scope of the present invention. Modified or changed embodiments are also included in the technical scope of the present invention.

Claims (24)

1. A heat-resistant steel, which consists of 0.25 to 0.35 C, 0.15 or less Si, 0.2 to 0.8 Mn, 0.3 to 0.6 Ni, 1.6 to 1.9 Cr, and 0.26 to 0.35 V by weight percentage , Mo of 0.6 to 0.9, W of 0.9 to 1.4, Ti of less than 0.01, N of 0.001 to 0.007, a total of 1.3 to 1.4 of Mo and W/2 and the balance of Fe and unavoidable impurities, wherein After tempering heat treatment, the heat-resistant steel is composed of bainite single-phase structure, ensuring 1.0 or more Fe, 0.8-0.9 Cr, 0.4-0.5 Mo, 0.3-0.5 W and 0.2 or more V moved into the precipitate, and the total amount of the precipitate was 3.5 or higher. 2. The heat-resistant steel according to claim 1, wherein Ti and/or N are replaced by Fe and C. 3. The heat-resistant steel according to claim 1 or 2, wherein the heat-resistant steel has a tempered bainite single-phase structure with an average prior austenite grain size of 100 μm or less, and even M, RC type precipitates, M, VC, R-type precipitates, M, QC-type precipitates, and MC-type precipitates were deposited in a bainite single-phase structure and exposed to high-temperature steam at a specified temperature for 100,000 hours, and the types of precipitates did not change. 4. A heat-resistant steel composed of 0.25 to 0.35 C, 0.15 or less Si, 0.2 to 0.8 Mn, 0.3 to 0.6 Ni, 1.6 to 1.9 Cr, and 0.26 to 0.35 V by weight percentage , Mo of 0.6 to 0.9, W of 0.9 to 1.4, Ti of less than 0.01, a total of 1.3 to 1.4 of Mo and W/2 and the balance of Fe and unavoidable impurities, wherein after tempering heat treatment, The heat-resistant steel is composed of a bainite single-phase structure, ensuring that 1.0 or more of Fe, 0.8 to 0.9 of Cr, 0.4 to 0.5 of Mo, 0.3 to 0.5 of W, and 0.2 or more of V are moved in by weight percentage sediment, and the total amount of sediment is 3.5 or higher. 5. The heat-resistant steel according to claim 4, wherein Ti and/or N are replaced by Fe and C. 6. The heat-resistant steel according to claim 4 or 5, wherein the heat-resistant steel has a tempered bainite single-phase structure with an average prior austenite grain size of 100 μm or less, and even M, RC type precipitates , M, VC, R-type precipitates, M, QC-type precipitates and MC-type precipitates are deposited in a bainite single-phase structure and exposed to high-temperature steam at a specified temperature for 100,000 hours, and the type of precipitate does not change . 7. A heat-resistant steel composed of 0.25 to 0.35 C, 0.15 or less Si, 0.2 to 0.8 Mn, 0.3 to 0.6 Ni, 1.6 to 1.9 Cr, and 0.26 to 0.35 V by weight percentage , Mo of 0.6 to 0.9, W of 0.9 to 1.4, N of 0.001 to 0.007, a total of 1.3 to 1.4 of Mo and W/2 and the balance of Fe and unavoidable impurities, wherein after tempering heat treatment, The heat-resistant steel is composed of a bainite single-phase structure, ensuring that 1.0 or more of Fe, 0.8 to 0.9 of Cr, 0.4 to 0.5 of Mo, 0.3 to 0.5 of W, and 0.2 or more of V are moved in by weight percentage sediment, and the total amount of sediment is 3.5 or higher. 8. The heat-resistant steel according to claim 7, wherein Ti and/or N are replaced by Fe and C. 9. The heat-resistant steel according to claim 7 or 8, wherein the heat-resistant steel has a tempered bainite single-phase structure with an average prior austenite grain size of 100 μm or less, and even M, RC type precipitates , M, VC, R-type precipitates, M, QC-type precipitates and MC-type precipitates are deposited in a bainite single-phase structure and exposed to high-temperature steam at a specified temperature for 100,000 hours, and the type of precipitate does not change . 10. A heat treatment method for heat-resistant steel, comprising: by weight percent, C of 0.25 to 0.35, Si of 0.15 or less, Mn of 0.2 to 0.8, Ni of 0.3 to 0.6, Ni of 1.6 to 1.9 Cr of 0.26-0.35, Mo of 0.6-0.9, W of 0.9-1.4, Ti of less than 0.01, N of 0.001-0.007, Mo and W/2 of 1.3-1.4 in total and the balance of Fe The steel ingot composed of and unavoidable impurities is heated to 980˜1030° C., cooled so that the cooling rate of the central portion of the steel ingot becomes at least 20° C./h or higher, and then subjected to tempering treatment. 11. A heat treatment method for heat-resistant steel, comprising: by weight percent, C of 0.25 to 0.35, Si of 0.15 or less, Mn of 0.2 to 0.8, Ni of 0.3 to 0.6, Ni of 1.6 to 1.9 Cr, 0.26-0.35 V, 0.6-0.9 Mo, 0.9-1.4 W, less than 0.01 Ti, a total of 1.3-1.4 Mo and W/2, and the balance of Fe and unavoidable impurities The steel ingot is heated to 980˜1030° C., cooled so that the cooling rate of the center portion of the steel ingot becomes at least 20° C./h or higher, and then subjected to tempering treatment. 12. A heat treatment method for heat-resistant steel, comprising: by weight percent, C of 0.25 to 0.35, Si of 0.15 or less, Mn of 0.2 to 0.8, Ni of 0.3 to 0.6, Ni of 1.6 to 1.9 Cr, 0.26-0.35 V, 0.6-0.9 Mo, 0.9-1.4 W, 0.001-0.007 N, a total of 1.3-1.4 Mo and W/2 and the balance of Fe and unavoidable impurities The steel ingot is heated to 980-1030°C, cooled so that the cooling rate of the central part of the steel ingot becomes at least 20°C/h or more, and then tempered. 13. A high-temperature steam turbine rotor comprising heat-resistant steel, the heat-resistant steel consists of 0.25-0.35 C, 0.15 or less Si, 0.2-0.8 Mn, 0.3-0.6 Ni, 1.6-0 Cr of 1.9, V of 0.26-0.35, Mo of 0.6-0.9, W of 0.9-1.4, Ti of less than 0.01, N of 0.001-0.007, a total of 1.3-1.4 of Mo and W/2 and the balance Composition of Fe and unavoidable impurities, wherein after tempering heat treatment, the heat-resistant steel is composed of bainite single-phase structure, ensuring 1.0 or more of Fe, 0.8 to 0.9 of Cr, 0.4 to 0.5 of Mo, W of 0.3 to 0.5, and V of 0.2 or more moved into the precipitate, and the total amount of the precipitate was 3.5 or more. 14. The high temperature turbine rotor according to claim 13, wherein the vicinity of the high temperature turbine rotor portion exposed to the highest temperature steam during smooth operation ensures a total amount of deposits of 2.8% or more after operation equivalent to 100,000 hours. 15. The high-temperature steam turbine rotor according to claims 13 and 14, wherein the high-temperature steam turbine rotor has a tempered bainite single-phase structure with an average particle size of prior austenite of 100 μm or less, and even M, RC type precipitates , M, VC, R-type precipitates, M, QC-type precipitates and MC-type precipitates are deposited in a bainite single-phase structure and are exposed to the highest temperature steam equivalent to 100,000 hours during smooth operation, and the types of precipitates are also do not change. 16. The high temperature steam turbine rotor according to claim 13, wherein Ti and/or N are replaced by Fe and C. 17. A high-temperature steam turbine rotor comprising heat-resistant steel, the heat-resistant steel consists of 0.25-0.35 C, 0.15 or less Si, 0.2-0.8 Mn, 0.3-0.6 Ni, 1.6-0 Cr of 1.9, V of 0.26-0.35, Mo of 0.6-0.9, W of 0.9-1.4, Ti of less than 0.01, Mo and W/2 of 1.3-1.4 in total, and the balance of Fe and unavoidable impurities Composition, wherein after the tempering heat treatment, the heat-resistant steel is composed of a bainite single-phase structure, ensuring 1.0 or more Fe, 0.8-0.9 Cr, 0.4-0.5 Mo, 0.3-0.5 W and V of 0.2 or more move into the precipitate, and the total amount of the precipitate is 3.5 or higher. 18. The high temperature turbine rotor according to claim 17, wherein the vicinity of the high temperature turbine rotor portion exposed to the highest temperature steam during smooth operation ensures a total amount of deposits of 2.8% or more after operation equivalent to 100,000 hours. 19. The high-temperature steam turbine rotor according to claim 17 or 18, wherein the high-temperature steam turbine rotor has a tempered bainite single-phase structure with an average particle size of prior austenite of 100 μm or less, and even M, RC type precipitates , M, VC, R-type precipitates, M, QC-type precipitates and MC-type precipitates are deposited in a bainite single-phase structure and are exposed to the highest temperature steam equivalent to 100,000 hours during smooth operation, and the types of precipitates are also do not change. 20. The high temperature steam turbine rotor according to claim 17, wherein Ti and/or N are replaced by Fe and C. 21. A high-temperature steam turbine rotor comprising heat-resistant steel, the heat-resistant steel consists of 0.25-0.35 C, 0.15 or less Si, 0.2-0.8 Mn, 0.3-0.6 Ni, 1.6-0 Cr of 1.9, V of 0.26-0.35, Mo of 0.6-0.9, W of 0.9-1.4, N of 0.001-0.007, a total of 1.3-1.4 of Mo and W/2 and the balance of Fe and unavoidable impurities Composition, wherein after the tempering heat treatment, the heat-resistant steel is composed of a bainite single-phase structure, ensuring 1.0 or more Fe, 0.8-0.9 Cr, 0.4-0.5 Mo, 0.3-0.5 W and V of 0.2 or more move into the precipitate, and the total amount of the precipitate is 3.5 or higher. 22. The high temperature turbine rotor according to claim 21, wherein the vicinity of the high temperature turbine rotor portion exposed to the highest temperature steam during smooth operation ensures a total amount of deposits of 2.8% or more after operation equivalent to 100,000 hours. 23. The high-temperature steam turbine rotor according to claims 21 and 22, wherein the high-temperature steam turbine rotor has a tempered bainite single-phase structure with an average particle size of prior austenite of 100 μm or less, and even M, RC type precipitates , M, VC, R-type precipitates, M, QC-type precipitates and MC-type precipitates are deposited in a bainite single-phase structure and are exposed to the highest temperature steam equivalent to 100,000 hours during smooth operation, and the types of precipitates are also do not change. 24. The high temperature steam turbine rotor according to claim 21, wherein Ti and/or N are replaced by Fe and C.