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Method for controlling widmannstatten structure in upgrade of C-Mn steel

A technology of Widmanderman's structure and control method, applied in the field of steel rolling, can solve the problems of TMCP steel plate performance and other problems, and achieve the effect of improving the Widmancer's structure without affecting the production rhythm, and improving the toughness and plasticity.

Active Publication Date: 2015-05-27
NANJING IRON & STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The idea of ​​low-cost upgrading production is to reduce the production of alloy elements, which requires rapid cooling to refine the grains, but this will easily lead to the appearance of Widmanstatten structure due to too fast cooling rate, thus bringing about the performance of TMCP steel plate aspects of the problem
[0004] Although some materials and documents have expounded on the causes and control measures of Wei's structure, they are all based on book theory or simulation experiments, so there are great limitations in field application. In addition, different steel types, different Under the process conditions, it is impossible to have a completely covered method to solve the occurrence of Widmanstatten structure in steel

Method used

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  • Method for controlling widmannstatten structure in upgrade of C-Mn steel
  • Method for controlling widmannstatten structure in upgrade of C-Mn steel
  • Method for controlling widmannstatten structure in upgrade of C-Mn steel

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Experimental program
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Effect test

Embodiment 1

[0029] The method for controlling the Widmanstatten structure of C-Mn upgraded steel in this embodiment, the chemical composition mass percentage of C-Mn upgraded steel is: C: 0.17%, Mn: 0.95%, P: 0.009%, S: 0.008%, Si: 0.22 %, Als: 0.025%, N is 0.0050%, the balance is Fe and unavoidable impurities;

[0030] The thickness of the steel billet taken is 180mm, and the thickness of the finished product is 14mm; the heating temperature is 1170°C, the soaking temperature is 1160°C, the heating time is 148min, and the furnace temperature is 1140°C; The stage cumulative reduction rate is 66.7% (42→14), the cooling start temperature is 761°C, the cooling rate is 10°C / s, the first 4 sets of headers are used for cooling, and the cooling intensity of the first 4 sets of headers is 2000m 3 / h, the last 6 sets of headers are weakly cooled, and the cooling strength of the last 6 sets of headers is 1500m 3 / h; the red temperature is 639°C.

Embodiment 2

[0032] The method for controlling the Widmanstatten structure of C-Mn upgraded steel in this embodiment, the chemical composition mass percentage of C-Mn upgraded steel is: C: 0.163%, Mn: 0.97%, P: 0.006%, S: 0.005%, Si: 0.24 %, Als: 0.030%, N is 0.0055%, the balance is Fe and unavoidable impurities;

[0033] The thickness of the steel billet taken is 180mm, and the thickness of the finished product is 22mm; the heating temperature is 1175°C, the soaking temperature is 1160°C, the heating time is 150min, and the furnace temperature is 1140°C; The stage cumulative reduction rate is 63.3% (60→22), the cooling start temperature is 775°C, the cooling rate is 12.5°C / s, the first 4 sets of headers are used for cooling, and the cooling intensity of the first 4 sets of headers is 2500m 3 / h, the last 6 sets of headers are weakly cooled, and the cooling strength of the last 6 sets of headers is 1900m 3 / h, the red temperature is 630°C.

Embodiment 3

[0035] The method for controlling the Widmanstatten structure of C-Mn upgraded steel in this embodiment, the chemical composition mass percentage of C-Mn upgraded steel is: C: 0.168%, Mn: 0.91%, P: 0.012%, S: 0.007%, Si: 0.21 %, Als: 0.036%, N is 0.0058%, the balance is Fe and unavoidable impurities;

[0036] The thickness of the steel billet taken is 220mm, and the thickness of the finished product is 30mm; the heating temperature is 1180°C, the soaking temperature is 1160°C, the heating time is 170min, and the furnace temperature is 1140°C; The cumulative reduction rate in the rolling stage is 58.3% (72→30), the starting cooling temperature is 770°C, and the cooling rate is 14°C / s. 3 / h, the last 6 sets of headers are weakly cooled, and the cooling strength of the last 6 sets of headers is 2300m 3 / h, the red temperature is 615°C.

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Abstract

The invention relates to a method for controlling widmannstatten structure in upgrade of C-Mn steel. The heating temperature is 1170-1180 DEG C, the soaking temperature is 1150-1160 DEG C, the tapping temperature is controlled at 1130-1140 DEG C, the finish rolling and initial rolling temperature is 810-930 DEG C, the finish rolling temperature is guaranteed to be 780-800 DEG C, accumulated reduction rate in finishing rolling is 50-70%, the cooling temperature is 760-780 DEG C, cooling speed is 10-15 DEG C / s, former 4 groups of collectors are used for forced cooling, the cooling intensity of the former 4 groups of collectors is 2000-3500m<3> / h, the last 6 groups of collectors are used for weak cooling, the cooling intensity of the last 6 groups of collectors is 1500-2500 m<3> / h, and the red temperature is 610 DEG C-640 DEG C. According to the method, the defect of widmannstatten structure in upgrade production of C-Mn steel is better overcome, widmannstatten structure is improved obviously, and the toughness and plasticity of the rolled steel plate are improved obviously.

Description

technical field [0001] The invention belongs to the field of steel rolling and relates to a method for controlling the structure of steel, in particular to a method for controlling the Widmanstatten structure of C-Mn upgraded steel. Background technique [0002] In hypoeutectoid steel or hypereutectoid steel, when the high temperature is cooled at a faster rate, the proeutectoid ferrite or cementite crystallizes from the austenite grain boundary along a certain crystal plane of austenite. Ingrown and precipitated in the form of needles. Under the optical microscope, it can be observed that the ferrite or cementite grown from the austenite grain boundary is approximately parallel, feathery or triangular, and there is a pearlite structure in between, which is called Widmanstatten structure. Most of the Widmanstatten structures encountered in actual production are ferritic Widmanstatten structures, which often appear with coarse austenite grains. Therefore, the mechanical prop...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C21D8/00C22C38/06
Inventor 王从道尹雨群曾周燏
Owner NANJING IRON & STEEL CO LTD
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