RU2336362C1 - Steel for monorails of mine monorail ways - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention refers to iron and steel metallurgy, particularly to steel used for production of monorails of mine monorail ways. Steel contains carbon, manganese, silicon, chromium, nickel, copper, vanadium, aluminium, nitrogen, iron and as impurities sulphur and phosphorus at a following ratio of elements, wt %: carbon 0.21-0.37, manganese 0.80-0.90, silicon 0.05-0.15, chromium 0.05-0.20, nickel 0.05-0.20, copper 0.03-0.20, aluminium 0.005-0.030, vanadium 0.01-0.06, nitrogen 0.005-0.025, sulphur not more, than 0.020, phosphorus not more, than 0.025, iron - the rest.

EFFECT: upgrading of operational resistance and mechanical properties of steel.

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Description

The invention relates to ferrous metallurgy, in particular to steel used for the production of monorail mine monorail. Known steel St5Gps [1], containing (in wt.%):

carbon 0.22-0.30 manganese 0.80-1.20 silicon 0.05-0.15 copper up to 0.40 chromium up to 0.35 nickel up to 0.35 sulfur no more than 0,050 phosphorus no more than 0,050 iron rest

Significant disadvantages of this steel are low strength properties and toughness of steel, as well as the associated low operational resistance of profiles made of this steel. Known as a prototype steel St5ps [1], containing (in wt.%):

carbon 0.28-0.37 manganese 0.50-0.80 silicon 0.05-0.15 sulfur no more than 0,050 phosphorus no more than 0,040 iron rest

Significant disadvantages of this steel are low mechanical properties and low operational stability of the monorail for mine monorails made of this steel.

The desired technical results of the invention are to increase the operational stability and mechanical properties of the monorail for mine monorails.

To achieve this, steel for monorail monorail mine, containing carbon, manganese, silicon, chromium, nickel, copper, iron and as impurities sulfur and phosphorus, additionally contains vanadium, aluminum and nitrogen in the following ratio of components (in wt.%):

carbon 0.21-0.37 manganese 0.80-0.90 silicon 0.05-0.15 chromium 0.05-0.20 nickel 0.05-0.20 copper 0.03-0.20 aluminum 0.005-0.030 vanadium 0.01-0.06 nitrogen 0.005-0.025 iron rest,

while impurities are contained in the following amounts: sulfur - not more than 0.020%, phosphorus - not more than 0.025%.

The inventive chemical composition of the steel is selected based on the following premises.

The carbon content is selected based on the provision of sufficient strength properties of steel. When its concentration in steel is less than 0.21%, the yield strength and temporary tensile strength decrease, and with an increase in carbon concentration of more than 0.37%, the values of these characteristics exceed the permissible limits.

The ratio of manganese is selected based on the fact that when the manganese content is up to 0.90%, the strength characteristics, toughness and cold resistance, as well as the resistance to steel cracking, are increased. The lower limit is chosen based on the fact that manganese at a content of less than 0.80% does not provide the required limit of strength characteristics.

Silicon within the claimed limits provides an increase in elongation and toughness. When the silicon concentration is less than 0.05%, the required deoxidation of the steel is not ensured, which leads to an increase in rejects due to surface defects. When the silicon content is more than 0.15%, the strength of ferrite increases, thereby reducing the plastic properties and toughness of steel.

Chrome, nickel and copper within specified limits provide strength characteristics of steel. With a lower content of these elements in combination with the selected concentration limits of carbon, manganese and silicon, the required ratio of yield strength and temporary tensile strength is not achieved. An increase in the concentration of chromium, nickel and copper in steel more than 0.20% leads to a significant decrease in plastic properties and toughness, and contributes to an increase in the sensitivity of steel to aging.

The aluminum content (0.005-0.030%) was selected based on the one hand, from the need to obtain fine real grain, on the other hand, from the exclusion of the formation of unacceptable alumina non-metallic inclusions, leading to the formation of fatigue cracks during operation of the monorail.

The vanadium content within the specified limits ensures the binding of nitrogen to the required amount of sparingly soluble nitrides, which contribute to the formation of fine austenite grains, thereby obtaining a fine-grained structure and, as a result, an increase in cold resistance and toughness both at room temperature and after mechanical aging. The introduction of vanadium in the amount of less than 0.01% does not lead to the formation of a fine-grained structure and, accordingly, an increase in impact strength. With an increase in the vanadium content of more than 0.06% in the steel, the amount of vanadium unbound into nitrides increases, which leads to the hardening of ferrite, thereby increasing the tendency of the steel to brittle fracture.

A nitrogen concentration of less than 0.005% does not lead to the formation of nitrides necessary for grinding the actual grain, and, as a result, reduces the toughness at positive and negative temperatures. With an increase in nitrogen of more than 0.025%, there may be cases of spotted segregation and the formation of bubbles in steel as a result of "nitrogen boiling".

The limitation of sulfur and phosphorus is selected based on ensuring the quality of the surface.

A series of experimental swimming trunks with the claimed chemical composition was smelted in DSP-100N10 arc furnaces. The chemical composition is shown in table 1. After casting the steel on the continuous casting machine, the monorail of the required profile was rolled. The tests were carried out according to the requirements of [2]. The test results are shown in table 2. Thus, the claimed chemical composition provides increased operational stability and mechanical properties of the monorail for mine monorail.

Table 1 The chemical composition of steel for monorail mine monorail, wt.% Structure FROM Si Mn S P Cr Ni Cu AI V N Fe one 0.21 0,03 0.82 0.005 0.015 0.05 0,03 0.05 0.005 0,03 0.003 ost 2 0.25 0.14 0.90 0.008 0.019 0.10 0,07 0.08 0.016 0.04 0.008 ost 3 0.30 0.10 0.88 0.016 0.019 0,07 0.09 0.17 0.018 0.06 0.010 ost four 0.31 0.08 0.85 0.005 0,028 0.15 0.05 0.12 0.006 0.06 0.013 ost 5 0.27 0.10 0.90 0,020 0,020 0.09 0.16 0.09 0.009 0.05 0,022 ost 6 0.37 0.15 0.87 0.017 0.018 0.05 0.20 0.20 0,025 0.06 0,025 prototype 0.28-0.37 0.05-0.15 0.50-0.80 ≤0.050 ≤0.040 ≤0.35 ≤0.35 ≤0.40 - - - ost

table 2 Mechanical properties of steel for monorail mine monorail Structure Temporary resistance, N / mm ² Yield strength, N / mm ² Relative extension, % Bending to parallelism of the sides (a - thickness, d - mandrel diameter) Impact strength, KCU, J / cm ² At
+ 20 ° С At
-20 ° C After mechanical aging one 450 290 thirty beats 150 one hundred 70 2 500 310 28 beats one hundred fifty fifty 3 520 370 26 beats one hundred 55 60 four 560 300 29th beats 120 70 60 5 570 350 thirty beats 120 70 80 6 580 320 26 beats 115 75 one hundred prototype 450-590 ≥285 ≥20 d = 3a 98 49 49

Information sources

1. GOST 380-88. “Carbon steel of ordinary quality. Stamps. "

2. GOST 535-88. “Long products and shapes made of carbon steel of ordinary quality. General specifications. "

Claims (1)

Steel for monorail mine monorail containing carbon, manganese, silicon, chromium, nickel, copper, iron and sulfur and phosphorus as impurities, characterized in that it additionally contains vanadium, aluminum and nitrogen in the following ratio, wt.%: carbon 0.21-0.37 manganese 0.80-0.90 silicon 0.05-0.15 chromium 0.05-0.20 nickel 0.05-0.20 copper 0.03-0.20 aluminum 0.005-0.030 vanadium 0.01-0.06 nitrogen 0.005-0.025 iron rest, while impurities are contained in the following amounts: sulfur - not more than 0.020%, phosphorus - not more than 0.025%.