RU2547053C1 - PRODUCTION OF HEXAGON PIPE BILLETS OF "TURN KEY" 181,8×3,5+0,3/-0,2×3750+20/-0 mm OF "12Х12М1БФРУ-Ш (ЭП450У-Ш)"-GRADE STEEL - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to metallurgy. ESR ingots are cast and turned to ingots-billets of 470×1540 mm. Through central 100±5 mm-dia bore is drilled therein. Blanks are heated to ductility temperature and pierced at screw rolling stand to sleeves-blanks. The latter are rolled to hot-formed rerolled pipe billets. Said pipes are straightened and cut to two billets. The latter are bored and turned. Pipe billets of 325×12 mm are rolled at "ХПТ450" and "ХПТ250" mills while pipes-billets are rolled at "ХПТ250" mill. Pipes are shaped at shaping Mill-400 to hexagon pipes-billets.

EFFECT: decreased metal consumption factor.

1 tbl

Description

The invention relates to metallurgical and pipe production, namely, to the production of ingots by electroslag remelting from steel of grade 12X12M1BFRU-Sh (EP450U-Sh), converting them into ingot ingots, to a method of manufacturing from ESH ingots-blanks to TPU 8-16 ″ with pilgrim by mills of hot rolled pipe sizes of 337 × 28 mm, machining them into billet pipes of size 325 × 12 mm, rolling of machined billet pipes of size 325 × 12 mm at KhPT450 and KhPT250 mills into billet pipes of size 202 ± 1.2 × 3.5 + 0.3 / -0.2 mm, profiling of conversion billet pipes into hexagonal billet pipes of turnkey size 181.8 ± 0.4 × 3.5 + 0.3 / -0.2 × 3750 + 20 / -0 mm and can be used at ZMZ OJSC on ingot ESR installations, at ChTPZ OJSC at TPU 8-16 ″ with pilgrim mills when converting ESW ingots-billets into hot-rolled pipe billets 337 × 28 mm in size, machining - boring and turning of hot rolled tubes into 325 × 12 mm sized pipes with a tolerance of ± 0.8% in diameter and ± 10.0% in the wall, rolling them on cold mills ХПТ450 and ХПТ250 into cold rolling mills rounded billet pipes with a size of 202 ± 1.2 × 3.5 + 0.3 / -0.2 mm, redistribution of billet pipes on a profiling “mill 400” into hexagonal billet pipes with a turnkey size of 181.8 ± 0, 4 × 3.5 + 0.3 / -0.2 × 3750 + 20 / -0 mm for use in nuclear power plants incorporating a new generation of fast neutron reactors.

In pipe-rolling production, there is a known method for producing hot-rolled commodity and conversion pipes of large and medium diameters in pipe-rolling plants with pilgrim mills from EShP ingots of steel grade 10X9MFB-Sh (TU 14-134-398-2003 "Billet pipe - ingots for boiler tubes EShP", TU 14-3R-55-2001 “Seamless steel pipes for steam boilers and pipelines”, TI 158-Tr. TB1-56-2007 “Production of seamless hot-rolled pipes for steam boilers and pipelines according to TU 14-ZR-55-2001”).

The disadvantage of this method is that the pipes after rolling have a large number of defects on the inner surface in the form of captures and grids of high cracks, require subsequent machining (boring) with the removal of metal of 8-10 mm per side. This steel grade has a hot ductility range of 1160–900 ° C and an increased coefficient of linear expansion. If ESR ingots-blanks are heated to a temperature of 1160 ° C, then when piercing ingots-blanks in a cross-helical rolling mill into the sleeves is pierced, the metal temperature in the deformation zone at the mandrel-inner surface of the sleeves increases by 50-70 ° C, depending on the diameter ingot blanks. When rolling sleeves on a pilgrim mill to tubes with an outer surface temperature of 1160 ° C or less, the end of rolling occurs at a temperature of 800-850 ° C depending on the diameter and wall thickness, which leads to tightening mandrels even with a taper of 4-5 mm instead of 1 , 0 according to TI 158-Tr. TB1-56-2007. The heating of the ESR ingots-blanks of this steel grade above 1160 ° C leads to overheating of the inner surface of the sleeves and the mass formation of internal captures and grids of high-cracking. These pipes must be rejected or bored onto a smaller wall with metal removal of more than 10 mm per side, which, in turn, leads to increased metal consumption and an additional laborious operation - boring of defective pipes.

There is also known a method for the production of seamless hot-rolled conversion lengthy pipes from hard-to-deform grades of steel and alloys, comprising rolling the billet sleeves into hot rolled billet tubes in a pilgrim mill in roll calibers with a difference between the inner diameter of the billet blanks and the average diameter of the mandrels equal to D _{g. vn} -D _cf.d = 10-20 mm, and with extracting µ≤6,0, where µ is the drawing coefficient on the pilgrim mill; D _g.vn - inner diameter of the sleeve, mm; D _{cf. d} - the average diameter of the mandrel, mm. Rolling pipes on a pilgrim mill in rolls with a round gauge with an angle of lateral release on the polishing section α = 25-30 °, where α is the angle of lateral release of the rolls of the pilgrim mill on the polishing section, deg., Or rolling on a pilgrim mill in rolls with an oval caliber with the ratio B / Η = 1.1-1.15, where B is the width of the caliber of the roll in the polishing section, mm; Η - roll caliber height, mm (RF Patent No. 2266132, class B21B 21/00, 03/27/2004, bull. No. 9).

The disadvantage of this method is that it is also aimed at reducing the number of puffs of mandrels when rolling pipes from hard to deform steel grades and alloys with an increased coefficient of linear expansion due to rolling in rolls with increased ovalization and does not solve the main technological issue of rolling the sleeves - rolling pilgrim heads at temperatures below the lower range of hot ductility of these grades of steel and alloys, the technology for producing high-quality liners on the inner surface during flashing Cove EEPROM preforms and - rolling the sleeves in the sleeve-blank in helical mill rolling.

In the pipe industry, there is also a known method for the production of hot-rolled commodity and conversion pipes of large and medium diameters from hard-to-deform steel grades and alloys in pipe rolling plants with pilgrim mills, including the casting of hollow ingots 1750-2100 mm high on electroslag remelting plants. The ingots are machined and bored into ingot ingots until the scale and microcracks are removed to a diameter of 400-620 mm with a diameter to wall thickness ratio of D / S = 3.0-4.0, the larger values of which correspond to ingots of smaller diameter. Then, the ingot blanks are heated to the temperature of ductility and stitched - rolled in a cross-helical rolling mill into sleeves with hoods µ = 1.5-1.7, large values of which correspond to sleeves of a larger diameter. Sleeves stitched - rolled with hoods µ = 1.5-1.6, rolled on pilgrim mills into conversion tubes, and sleeves stitched - rolled with hoods µ = 1.6-1.7 - into commodity pipes (RF Patent No. 2311979 Cl. B21B 21/00, 12/10/2007).

The disadvantage of this method is that it only partially reduces the formation of defects on the inner surfaces of the sleeves by reducing the drawing coefficient (squeezing the sleeve blanks along the wall) in the deformation zone during firmware - rolling the sleeve blanks from corrosion-resistant hard-deformed steel grades and alloys with low temperature range of hot ductility and a high coefficient of linear expansion in transverse helical rolling mills. The disadvantage of this method also relates to the fact that the method of manufacturing hollow sleeve blanks is significantly time-consuming and metal-consuming, because mechanical processing is required - turning and boring of hollow ESR ingots into blanks. This method does not solve technological issues of heating ESR ingots from 12Kh12M1BFRU-Sh steel, flashing and rolling of steel tubes from hard-to-form steel grades and alloys with a low temperature range of hot ductility and a high coefficient of linear expansion and rolling them at HPT mills into steel tubes of 202 ± 1.2 × 3.5 + 0.3 / -0.2 mm for their subsequent profiling into hexagonal billet pipes measuring 181.8 ± 0.4 × 3.5 + 0.3 / -0.2 × 3750 + 20 / -0 mm for new generation fast neutron reactors.

In the pipe industry, there is a known method for the production of hexagonal tubular cover pipes with a turnkey size of 257 + 2 / -3 × 6 + 2 / -1 × 4300 + 80 / -30 mm from low-ductility steel with a boron content of 1.3-1.8%, including mechanical processing - boring and turning, degreasing, induction processing, ultrasonic testing, drilling holes for the pulling chain during profiling, coating pipes with salt grease and warm profiling pipes of two to three times the length, the value of which is determined from the expression:

L _mp. = (2-3) L _kp. + L _nep. + L _ko ,

where L is the length of the hexagonal tube-whip, mm;

L _nep. - the length of the cylindrical part of the workpiece-pipe for drilling an axial hole

under the kingpin of the pull chain and the transition section from the circle to the hexagon, mm;

L _kp. - the length of the hexagonal pipe billet, mm;

L _ko is the length of the end trim,

and cutting pipes to a measured length, selecting templates for making samples for mechanical testing and removing end trimmings is carried out after checking the geometric dimensions and marking of the hexagonal tubing tubes (RF Patent No. 22243636, class B21B 23/00, 05/20/2005).

This method is aimed at the production of hexagonal pipes from steel with a boron content of 1.3 to 1.8% for storage and transportation of spent nuclear fuel and does not solve the technological and structural issues of the production of hexagonal pipe billets with a size of 181.8 ± 0.4 × 3 , 5 + 0.3 / -0.2 × 3750 + 20 / -0 mm from steel grade 12Kh12M1BFRU-Sh (EP450U-Sh) for new generation fast-neutron reactors.

In the pipe industry, a method is known for producing cold-rolled large and medium-diameter pipes from hard-deformed steel grades and alloys with increased accuracy on the wall, including rolling the welded billet in calibers with a variable radius into a cold-rolled commodity pipe with a maximum diameter with an extractor μ = 1.4-1, 7 and compression on the wall of at least 25%, while during subsequent rolls, the hood gradually increases by 0.05-0.10 to 1.7-2.0, and large values of hoods and wall compressions are taken for steels with a high content m of chromium and nickel, the conversion pipe billet is rolled into a commodity or conversion cold-rolled pipe of maximum diameter with a ratio of diameter to wall thickness of the pipe D / S = 40-50, which during subsequent rolling is rolled into pipes of smaller diameter with an increase in the D / S ratio from 2 to 10, and the last roll is performed with the ratio D / S = 50-75.

The disadvantage of this method is that it is aimed at the technology for the production of cold-rolled large and medium diameter pipes from hard-deformed steel grades and alloys with increased accuracy on the wall from welded billets and does not solve technological and structural issues in the production of turn-key hexagonal tubes-blanks 181 , 8 ± 0.4 × 3.5 + 0.3 / -0.2 × 3750 + 20 / -0 mm made of steel grade 12Kh12M1BFRU-Sh (EP450U-Sh) for new generation fast-neutron reactors.

In the pipe industry, there is a known method for the production of prototypes of hexagonal tube blanks with a turnkey size of 181.8 × 3.5 × 3750 + 20 / -0 mm from steel grade 12Kh12M1BFRU-Sh (EP450U-Sh) for new generation fast reactors neutrons (protocol No. 60/11 of 08/03/2011 and TU 1367-043-00186654-2012 (experimental batch) "Seamless cold-deformed hexagonal tubes of steel grade 12X12M1BFRU-Sh (EP450U-Sh)", including ingot casting with electroslag remelting of size 485 × 1540 mm, turning of ingots into ingot blanks of size 470 × 1540 mm, drilling in ingot blanks central of a hole with a diameter of 100 ± 5 mm, heating to a temperature of 1180-1200 ° C, piercing in a cross-helical rolling mill into sleeves of size 480hvn. 315 × 2400 mm, rolling the sleeves on pilgrim mills into red hot-formed pipe billets of 344 × 31 × 6600 mm in caliber 351 mm, a hot-saw blade for cutting technological waste - pilgrim heads and seed ends, straightening pipes, cutting pipes into two equal length pipes and machining - boring and turning them into 325 × 12 × 3300 mm conversion pipes with a tolerance of ± 1.0% in diameter and thickness not walls ± 12.5% with metal removal on the outer and inner surfaces of 9.5 mm each with a surface finish of R _z ≤30 μm, rolling of machined pipes of 325 × 12 × 3300 mm in size on mills ХПТ450 and ХПТ250 into conversion pipes of size 202 × 3.5 mm with a tolerance of ± 0.8% in diameter and ± 10.0% in wall thickness.

The disadvantage of this method is that when redistributing ingots and blanks of ESRs of 470 × 1540 mm in size to hot-rolled mechanically processed pipes of 325 ± 3.25 × 12 ± 1.5 × 3300 mm in size, even with triple rolling them on KhPT450 and KhPT250 mills , cold-rolled pipes with a size of 202 × 3.5 mm with a tolerance of ± 1.2 mm in diameter and a wall of + 0.3 / -0.2 mm are problematic to obtain. In the production of hot-rolled chimneys with a size of 325 × 12 mm, increased waste is obtained by non-multiplicity. The piercing of ESR ingots-blanks in a cross-helical rolling mill at a heating temperature of 1180-1200 ° C leads to an increase in temperature at the border of the mandrel with the inner surface of the sleeves to 1250-1270 ° C, which for this steel grade is fraught with overheating of the inner surface and the formation of a grid of high cracks, which, in turn, leads to marriage or an increase in metal removal during boring of hot-rolled pipes into steel machined pipes measuring 325 × 12 mm.

The closest technical solution (prototype) is a method for the production of pipes from hardly deformable grades of steel and alloys with an increased coefficient of linear expansion, including heating the working part of the mandrel to an average temperature equal to or greater than the required temperature of the front end of the pipe at the moment of its descent from the mandrel T _{cf.d .} ≥T _per.k.t., where Τ _av.d. - average temperature of the mandrel before rolling, ° C; T _lane - the required temperature of the front end of the pipe at the moment of its descent from the mandrel, ° C, heating of the working part of the mandrel with a temperature difference along the length of the working part not more than 100 ° C, i.e. T _max -T _min <100 ° C, where T _max is the maximum temperature of the working part of the mandrel in the zone of intense deformation, ° C; T _min - the minimum temperature of the working part of the mandrel, ° C (RF Patent No. 2214312, class B21B 21/00, 10/20/2003, bull. No. 29).

The disadvantage of this prototype, as well as the above analogues, is that it is aimed at reducing the number of puffs of mandrels when rolling pipes from hard to deform grades of steel and alloys with an increased coefficient of linear expansion by heating the mandrels before rolling and during the rolling process. This method does not solve the main technological issues: roll-up of sleeves - break-in of pilgrim heads at temperatures below the lower hot plasticity interval of these grades of steel and alloys and, all the more, the technology of producing high-quality shell sleeves on the inner surface during the flashing of ESR ingots-blanks and firmware-rolling of blanks-blanks in the sleeves in the cross-rolling mill.

The objective of the proposed method is the production of cold rolled pipes in size 202 × 3.5 mm with a diameter tolerance of ± 1.2 mm (± 0.6%) and a wall of + 0.3 / -0.2 mm (+ 8.5 / - 5.5%) instead of ± 0.8% in diameter and ± 10% in the wall (GOST 9941 high accuracy), reduction or complete elimination of defects on the inner surface of the sleeves when piercing ingot blanks, reducing metal consumption, when redistributing an ESR ingot - hot rolled pipe - a machined pipe converted by changing the pattern of deformation of the sleeves on the pilgrim mill during the production of hot rolled tubes, mastering the production of hexagonal billets of size 181.8 ± 0.4 × 3.5 + 0.3 / -0.2 × 3750 + 20 / -0 mm from 12Kh12M1FBRU-Sh brand ingots for equipping nuclear power plants with new reactors generation with fast neutrons, and consequently, the reduction in the cost of hexagonal workpieces with a low temperature range of hot ductility.

The technical result is achieved by the fact that in the known method for the production of hexagonal billets of "turnkey" size 181.8 ± 0.4 × 3.5 + 0.3 / -0.2 × 3750 + 20 / -0 mm of steel grade 12Х12М1БФРУ-Ш (ЭП450У-Ш) for fast neutron reactors, including casting ingots by electroslag remelting, turning ingots into ingot blanks with a size of 470 × 1540 mm, drilling in ingot blanks of a central hole with a diameter of 100 ± 5 mm, heating to ductility temperature, firmware in a cross-helical rolling mill into sleeves, rolling of sleeves on pilgrim mills in a conversion plant f hot-deformed billet pipes, a hot-cut saw for cutting technological waste — pilgrim heads and seed ends, straightening pipes, cutting pipes into two slabs, machining — boring and turning into billet pipes, rolling blanks of 325 × 12 mm on mills ХПТ450 and ХПТ250, rolling of billet pipes at the mill ХПТ250, profiling of pipes in the profiling “mill 400” into hexagonal billet pipes, while the nominal outer diameter of the pipes and permissible deviations are determined from the expressions:

where B is the nominal size of the turnkey hexagonal pipe billet, mm; tg30 ° - the angle between the diameter of the circumscribed circle and the face of the hexagonal pipe blank, deg .; n is the number of faces, pcs .; r is the inner radius of the rounding of the faces of the hexagon, mm; s is the nominal wall thickness of the hexagonal billet pipe, mm; γ = (1.015-1.03) - coefficient taking into account the magnitude of the tightening of the perimeter of a round pipe when profiling it into a hexagonal pipe billet; ± 0.4 - tolerance on the size of the "key" of the hexagonal pipe billet, mm.

A comparative analysis of the proposed solution with the prototype shows that the claimed method differs from the known one in that the ingots are cast by electroslag remelting, the ingots are turned into ingot ingots with a size of 470 × 1540 mm, drilling in ingots-blanks of a central hole with a diameter of 100 ± 5 mm, heating to ductility temperatures, piercing in a cross-helical rolling mill into sleeves, rolling sleeves on pilgrim mills into hot-deformed pipe billets, cutting off a hot cutting saw of technological waste s - pilgrim heads and seed ends, straightening pipes, cutting pipes into two slabs-blanks, machining - boring and turning into blanks, rolling blanks of 325 × 12 mm in size on mills ХПТ450 and ХПТ250, rolling of blanks on KhPT250 mill, profiling pipes in the profiling “mill 400” into hexagonal billet pipes, while the nominal outer diameter of the pipes and the permissible deviations are determined from the expressions:

where B is the nominal size of the turnkey hexagonal pipe billet, mm; tg30 ° - the angle between the diameter of the circumscribed circle and the face of the hexagonal pipe blank, deg .;

n is the number of faces, pcs .; r is the inner radius of the rounding of the faces of the hexagon, mm;

s is the nominal wall thickness of the hexagonal billet pipe, mm; γ = (1.015-1.03) - coefficient taking into account the magnitude of the tightening of the perimeter of a round pipe when profiling it into a hexagonal pipe billet; ± 0.4 - tolerance on the size of the "key" of the hexagonal pipe billet, mm. Thus, the claimed method meets the criterion of "inventive step".

Comparison of the proposed solution (method) not only with the prototype, but also with other technical solutions in the art did not allow them to identify signs that distinguish the claimed solution from the prototype, which allows us to conclude that the patentability condition is “inventive step”.

The method has been tested on a pipe-rolling installation with pilgrim mills 8-16 ″, mills KhPT450 and KhPT250 and a profiling “mill 400” of ChTPZ OJSC. According to the existing technology, 2 ingot blanks with a size of 470 × 100 × 1540 mm with a total weight of 4040 kg were heated in a methodical furnace to a temperature of 1160 and 1170 ° C. The piercing of ingot blanks in a cross-helical rolling mill was performed on a mandrel with a diameter of 300 mm. When flashing on the liners there were internal captives and small flaws. Sleeves were rolled on a pilgrim mill in rolls with a caliber of 351 mm on mandrels with a diameter of 283/287 mm and a taper of 4.0 mm into transfer tubes of 344 × 31 mm in size. The tubes were rolled with carbon-based washers with feed sleeves into the deformation zone m = 20-22 mm. The pipes came off the mandrel satisfactorily, because the temperature of the end of rolling was 860-870 ° C. On the inner surface of the pipes were captives and transverse flaws. The pipes were straightened on a straightening machine and cut into two pipe blanks measuring 344 × 31 × 3300 mm. Billet pipes were bored to remove internal defects, and then turned to a diameter of 325 mm. The wall thickness of the pipes ranged from 9.5 to 12.5 mm. Pipes were transferred to workshop No. 5 and on the KhPT450 and KhPT250 mills were rolled into conversion pipes of 202 × 3.5 mm in size along the routes: 325 × 12 × 3300 ---- 273 × 8 × 5500 ---- 250 × 5 × 9100 --- 202 × 3.5 × 15600 mm. Cold-rolled pipes of 202 × 3.5 × 15600 mm in size were cut into three workpieces of equal length (5200 mm). Thus, when redistributing 2 ingots with a size of 470 × 1540 mm, 12 billet pipes of 202 × 3.5 × 5200 mm in size were obtained, which at the “mill 400” were profiled into hexagonal billet pipes of 181.8 × 3.5 × 5200 size mm 12 billet pipes with a size of 202 × 3.5 × 5200 mm were specified for profiling. Twelve hexagonal billet pipes with dimensions of 181.8 ± 0.6 × 3.5 + 0.5 / -0.6 × 5200 mm were profiled. The transition parts from the circle to the hexagon were removed from the pipe blanks and the ends on the opposite side were cut. Received 12 hexagonal tube blanks measuring 181.8 ± 0.6 × 3.5 + 0.5 / -0.6 × 3750 + 20 / -0 mm. One hexagonal billet pipe is rejected along the wall (4.2 mm instead of 3.8 mm). Eleven billet pipes are accepted as conditionally suitable. The total expenditure coefficient of the metal according to the existing technology for the redistribution of EAW ingots-blanks with a size of 470 × 1540 mm is a hot-rolled conversion machined pipe with a size of 325 × 12 × 3300 mm and a cold-rolled conversion pipe with a size of 202 × 3.5 × 5200 mm and a commodity hexagonal billet pipe size 181.8 ± 0.6 × 3.5 + 0.5 / -0.6 × 3750 + 20 / -0 mm amounted to 5.933.

According to the proposed technology, 2 ingot billets with a size of 470 × 1650 mm and a total mass of 4492 kg were drilled to a diameter of 100 ± 5 mm, heated in a methodical furnace to a temperature of 1130 ° C, and sewn in a cross-helical mill in sleeves of size 480 × ext. 315 × 2560 mm and rolled on a pilgrim mill into hot-rolled chimneys measuring 337 × 28 × 8500 mm. Pipes were cut into two equal parts, bored and turned into steel machined pipe blanks measuring 325 × 12 × 4250 mm. On one billet pipe on the outer surface there was a black area of 20 × 40 mm, which was removed by stripping with a surface purity of R _z ≤30 μm. Then, machined billet pipes of 325 × 12 × 4250 mm in size were rolled in workshop No. 5 at the KhPT450 and KhPT250 mills along the routes: 325 × 12 × 4000 --- 273 × 8 × 7200-250 × 5 × 12200 mm. Then, the nominal diameter and its geometrical dimensions were determined, which are necessary for producing hexagonal tube blanks measuring 181.8 ± 0.4 × 35 + 0.3 / -0.2 × 3750 + 20 / -0 mm. Pipes 250 × 5 × 12200 mm in size were cut into two billet pipes of 250 × 5 × 4800 mm in size and one billet pipe of 250 × 5 × 2600 mm in size, which were then rolled on the KhPT250 mill into 202 × billet pipe 3.5 × 8200 and 202 × 3.5 × 4300 mm, and then profiled in a profiling “mill 400” into hexagonal pipes of “turnkey” size 181.8 ± 0.4 × 3.5 + 0.3 / -0 , 2 × 8200 and 181.8 ± 0.4 × 3.5 + 0.3 / -0.2 × 4300 mm, which were cut into billet pipes measuring 181.8 ± 0.4 × 3.5 + 0 , 3 / -0.2 × 3750 + 20 / -0 mm with the execution of all subsequent operations in the technological process and adopted in accordance with the technical documentation. For profiling, 8 pipes with a size of 202 ± 0.4 × 3.5 + 0.3 / -0.2 × 8200 mm and 4 pipes with a size of 202 ± 0.4 × 3.5 + 0.3 / -0.2 were specified × 4300 mm. After profiling, 20 hexagonal billet pipes were obtained, of which, during the acceptance process, one billet pipe was rejected according to the wall thickness (the wall thickness at two points was 3.1 and 3.2 mm). The total expenditure coefficient of the metal according to the proposed technology for the redistribution of ESR ingots of 470 × 1650 mm in size is a hot-rolled conversion machined pipe of 325 × 12 × 4250 mm in size — a cold-rolled conversion pipe of 202 × 3.5 × 8200 and 202 × 3.5 × 4300 mm in size - commodity hexagonal pipe billet size 181.8 ± 0.4 × 3.5 + 0.3 / -0.2 × 3750 + 20 / -0 mm amounted to 3.681. Thus, when redistributing 2 ingot billets with a size of 485 × 1650 mm, 19 hexagonal tube billets with a size of 181.8 ± 0.4 × 3.5 + 0.3 / -0.2 × 3750 + 20 / -0 mm total weighing 1220.4 kg.

Data on rolling hot-rolled machined tubes of 325 × 12 mm in size from 12Kh12M1BFRU-Sh (EP450U-Sh) steel, rolling them at KhPT450 and KhPT250 mills into steel tubes with increased accuracy in diameter and wall of 202 ± 1.2 × 3.5 + 0.3 / -0.2 mm along routes 325 × 12--273 × 8--250 × 5--202 × 3.5 mm according to the existing and proposed technologies for profiling them into hexagonal workpieces of size “Turnkey” 181.8 ± 0.4 × 3.5 + 0.3 / -0.2 × 3750 + 20 / -0 mm for fast neutron reactors are shown in the table. The table shows that in the production of cold rolled cold-rolled pipes of size 202 ± 1.2 × 3.5 + 0.3 / -0.2 mm from steel grade 12X12M1BFRU-Sh, according to the proposed technology, 19 high-quality hexagonal tubes-blanks were obtained, a decrease in consumption a metal coefficient of 2252 kg per ton of hexagonal billet pipes, and the laborious operation of boring pipes with a size of 344 × 31 mm with defects on the inner surface into redistributed machined pipes with a size of 325 × 12 mm is excluded.

Using the proposed method for the production of hexagonal pipe blanks with a turnkey size of 181.8 ± 0.4 × 3.5 + 0.3 / -0.2 × 3750 + 20 / -0 mm from steel grade 12X12M1BFRU-Sh (EP450U- Sh) for new generation reactors with fast neutrons, it was possible to obtain hexagonal billet pipes with specified geometric dimensions, to reduce the expenditure coefficient of the metal during the redistribution of the ESR ingot - hot-rolled hot-rolled pipe with a size of 325 × 12 mm - cold-rolled cold-rolled pipe with a size of 202 × 3.5 mm - commodity a six-sided billet pipe measuring 181.8 ± 0.4 × 3.5 + 0.3 / -0.2 × 3750 + 20 / -0 mm, and the trace Therefore, reduce their cost.

Claims (1)

Method for the production of turn-key hexagonal tube blanks 181.8 ± 0.4 × 3.5 + 0.3 / -0.2 × 3750 + 20 / -0 mm from steel grade 12X12M1BFRU-Sh for fast neutron reactors , including ingots casting by electroslag remelting, turning ingots into ingot blanks of 470 × 1650 mm in size, drilling a central hole with a diameter of 100 ± 5 mm in heating ingots, heating to ductility temperature, piercing in a cross-helical rolling mill into sleeves, rolling the sleeves on pilgrim mills in hot-deformed pipe billet, cut off with a hot saw cutting technological waste - pilgrim heads and seed ends, straightening pipes, cutting pipes into two blanks, machining - boring and turning into blanks, rolling blanks of 325 × 12 mm in size on KhPT450 and KhPT250 mills, rolling pipes - blanks on the mill ХПТ250, profiling pipes in the forming mill 400 in hexagonal tubes-blanks, while the nominal outer diameter of the pipes and the permissible deviations are determined from the expressions:
$$D_{n\mathrm{about}m}=\left(\frac{Btg{\mathrm{thirty}}^{\circ }{n}^2-2\pi \left(r+s\right)}{\pi n}\right)\gamma ,$$

$$$$

$$\Delta D=\pm \frac{n0.4}{2},$$

where B is the nominal size of the turnkey hexagonal pipe billet, mm;
tg30 ° - the angle between the diameter of the circumscribed circle and the face of the hexagonal pipe-workpiece, deg .;
n is the number of faces, pcs .;
r is the inner radius of the rounding of the faces of the hexagon, mm;
s is the nominal wall thickness of the hexagonal pipe - billet, mm;
γ = (1.015-1.03) - coefficient taking into account the magnitude of the tightening of the perimeter of a round pipe when profiling it into a hexagonal pipe billet;
± 0.4 - tolerance on the size of the hexagonal pipe billet, mm.