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Method for cooling low-alloy hot-rolled H-shaped steel with yield strength of 550MPa after rolling

A technology of yield strength and cooling method, applied in metal rolling and other directions, can solve the problems of high alloying element content, reduce production efficiency, increase rolling mill load and energy consumption, etc., achieve low alloying element content, reduce production costs, improve The effect of welding performance

Active Publication Date: 2012-09-19
MAGANG (GROUP) HOLDING CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] At present, my country's H-beam manufacturers have developed 420MPa, 460MPa and other H-beams, but they are all produced by hot rolling with the addition of alloying elements, and the amount of alloying elements is relatively high, such as BS 55C with a yield strength of 420MPa Hot-rolled H-shaped steel adopts Nb and V composite microalloying, the V content is 0.08-0.12wt%, and the Nb content is 0.040-0.060wt%. The 550MPa grade H-shaped steel has not yet been developed. If it is also produced by this method, its alloy The element content will be higher, resulting in high steelmaking costs; and due to the high alloy element content, carbon content, etc., the weldability will deteriorate; in addition, in order to obtain better impact toughness, a very low final rolling temperature is required, which is both Increase the load and energy consumption of the rolling mill, and reduce the production efficiency

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0017] Post-rolling cooling method for low-alloy hot-rolled H-beams with a yield strength of 550 MPa, low-alloy hot-rolled H-beams with a yield strength of 550 MPa, by mass percentage (wt%), the composition is: C: 0.14, Si: 0.42, Mn: 1.48 , P: 0.025, S: 0.018, V: 0.10, N: 0.011, Als: 0.006, the rest is iron and residual trace impurities;

[0018] The rolling process of the H-shaped steel is: heating in the billet heating furnace → rolling in the billet opening machine → rolling in a universal rolling mill → two-stage rapid cooling after rolling; specifically:

[0019] The cast slab is heated to 1245°C by the heating furnace; the rolling stage of the blanking machine is 1145°C, the final rolling temperature is 995°C; the universal rolling mill is 925°C, and the final rolling temperature is 855°C; Rapid water cooling, the process parameters of the first stage of rapid water cooling are: the temperature at the beginning of cooling of the H-shaped steel flange and web is 850°C, th...

Embodiment 2

[0022] Cooling method after rolling of low-alloy hot-rolled H-shaped steel with a yield strength of 550MPa, low-alloy hot-rolled H-shaped steel with a yield strength of 550MPa, in terms of mass percentage (wt%), the composition is: C: 0.18, Si: 0.35, Mn: 1.56, P: 0.021, S: 0.009, V: 0.11, N: 0.013, Als: 0.017, the rest is iron and residual trace impurities;

[0023] The rolling process of the H-shaped steel is: heating in the billet heating furnace → rolling in the billet opening machine → rolling in a universal rolling mill → two-stage rapid cooling after rolling; specifically:

[0024] The cast slab is heated to 1210°C by the heating furnace; the rolling stage of the blanking machine is 1105°C, and the final rolling temperature is 1010°C; the universal rolling mill is 935°C, and the final rolling temperature is 880°C; Rapid water cooling, the process parameters of the first stage of rapid water cooling are: the temperature at the beginning of cooling of the H-shaped steel fl...

Embodiment 3

[0027] Cooling method after rolling of low-alloy hot-rolled H-shaped steel with a yield strength of 550MPa, low-alloy hot-rolled H-shaped steel with a yield strength of 550MPa, in terms of mass percentage (wt%), the composition is: C: 0.16, Si: 0.48, Mn: 1.40, P: 0.020, S: 0.005, V: 0.12, N: 0.014, Als: 0.026, the rest is iron and residual trace impurities;

[0028] The rolling process of the H-shaped steel is: heating in the billet heating furnace → rolling in the billet opening machine → rolling in a universal rolling mill → two-stage rapid cooling after rolling; specifically:

[0029] The cast slab is heated to 1235°C by the heating furnace; the rolling stage of the blanking machine is 1135°C, and the final rolling temperature is 1025°C; the universal rolling mill is 960°C, and the final rolling temperature is 900°C; Rapid water cooling, the process parameters of the first stage of rapid water cooling are: the temperature at the beginning of cooling of the H-shaped steel fl...

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Abstract

The invention discloses a method for cooling a low-alloy hot-rolled H-shaped steel with yield strength of 550MPa after rolling, wherein the low-alloy hot-rolled H-shaped steel with the yield strength of 550MPa comprises following components by mass: 0.13-0.18% of C, 0.30-0.50% of Si, 1.40-1.60% of Mn, not more than 0.025% of P, not more than 0.025% of S, 0.10-0.12% of V, 0.010-0.014% of N, 0.003-0.030% of Als, and the balance of iron and residual trace impurities; a rolling process of the H-shaped steel is as follows: heating casting blank in a heating furnace, performing rolling by a cogging mill, performing rolling by a universal rolling mill and quickly cooling the steel in two-stage manner after rolling; the method adopts the two-stage quick cooling method after the H-shaped steel is hot-rolled, so that the high-temperature H-shaped steel is cooled to proper temperature at short time; by using the cooling method after colling, texture state of the H-shaped steel with fine crystal particles and complex phase texture is obtained, adding amount of the alloy elements is drastically reduced, production cost is notably reduced when requirement of high-strength performance is satisfied, and welding performance of the steel and production efficiency are improved.

Description

technical field [0001] The invention relates to the field of low-alloy steel, in particular to a post-rolling cooling method for low-alloy hot-rolled H-shaped steel with a yield strength of 550 MPa. Background technique [0002] Hot-rolled H-shaped steel is an economical cross-section profile with excellent mechanical properties and superior performance. The main performances are: 1) The section modulus is large, and it can save 10-15% of metal under the same load conditions, thereby reducing the cost ; 2) Beautiful appearance, easy processing, its flange inside and outside are parallel, various H-beams of different specifications can be easily combined into many components of different shapes and sizes, easy to connect, easy to machine, can improve production efficiency and Reduce the labor intensity of producers; 3) Improve the structural strength. Compared with ordinary I-beams, when the cross-sectional area or weight is roughly the same, its bending resistance and compre...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/12C21D8/00B21B1/088
Inventor 汪开忠孙维程鼎张卫斌奚铁
Owner MAGANG (GROUP) HOLDING CO LTD
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