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Production method of graphitized free-machining steel

A technology of free-cutting steel and production method, which is applied in the field of producing graphitized free-cutting steel, can solve the problems of difficulty in production and implementation, high production cost and high cooling temperature, and achieves short graphitization tempering time, low production cost, Evenly distributed effect

Inactive Publication Date: 2011-12-14
武钢集团有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

U.S. Patent No. 5830285 is to add a small amount of B to the steel, and then directly quench and temper after hot rolling. However, the starting and cooling temperature is relatively high, the cooling rate is required to be large, and the tempering time must be more than 10 hours, which is difficult. production implementation in practice
In China, only Shougang Technology Research and Beijing University of Science and Technology have carried out work in this area, such as "Development of Hypoeutectoid Graphitized Free-cutting Steel, "Steel and Steel" 2008.43(8).73", the method is also to carry out steel for a long time ( More than 10h) annealing, the production cost is higher

Method used

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  • Production method of graphitized free-machining steel
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  • Production method of graphitized free-machining steel

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] A kind of production method of graphitized free-cutting steel, its step:

[0027] 1) The main chemical composition and weight percentage are: 0.453%C, 1.70%Si, 1.5%Al, 0.34%Mn, <0.020%P, <0.035%S, and the balance is Fe and the slab is heated to 1200-1205°C;

[0028] 2) Carry out heat preservation: heat preservation at a temperature of 1200-1205°C for 60 minutes;

[0029] 3) Cooling: cooling the slab to 1050-1060°C at a cooling rate of 10°C / s;

[0030] 4) Rough rolling: 3 times of rough rolling at 1050-1060°C, controlling the reduction ratio of each pass at 20%;

[0031] 5) Cooling: After rough rolling, cool the rough rolled plate to 850-855°C at a cooling rate of 5°C / s;

[0032] 6) Finish rolling: carry out finish rolling according to 4 passes, control the interval time of each pass for 2.5 seconds, and the deformation amount of each pass is 10%;

[0033] 7) Air cooling: the air cooling time is 30 seconds;

[0034] 8) Perform rapid water cooling: cool to room temper...

Embodiment 2

[0038] A kind of production method of graphitized free-cutting steel, its step:

[0039] 1) The main chemical composition and weight percentage are: 0.43%C, 1.50%Si, 0.005%B, 0.45%Mn, 0.009%P, 0.010%S, and the balance is Fe and the slab is heated to 1210-1215°C;

[0040] 2) Keep warm: keep warm for 80 minutes at a temperature of 1210-1215°C;

[0041] 3) Cooling: cooling the billet to 1070-1075°C at a cooling rate of 12°C / s;

[0042] 4) Rough rolling: carry out 5 times of rough rolling at 1070-1075°C, and control the reduction ratio of each pass at 26%;

[0043] 5) Cooling: After rough rolling, cool the rough rolled plate to 880-885°C at a cooling rate of 8°C / s;

[0044] 6) Carry out finish rolling: carry out finish rolling according to 5 passes, control the interval time of each pass for 2 seconds, and the deformation amount of each pass is 25%;

[0045] 7) Air cooling: the air cooling time is 40 seconds;

[0046] 8) Rapid water cooling: cooling to room temperature at a co...

Embodiment 3

[0050] A kind of production method of graphitized free-cutting steel, its step:

[0051] 1) The main chemical composition and weight percentage are: C: 0.62%, Si: 0.95%, Al: 0.05%, Mn: 0.80%, P: 0.0176%, S: 0.182%, Zr: 0.15%, Nb: 0.1% , the billet with the balance being Fe is heated to 1225-1230°C;

[0052] 2) Keep warm: keep warm for 100 minutes at a temperature of 1225-1230°C;

[0053] 3) Cooling: cooling the billet to 1090-1097°C at a cooling rate of 15°C / s;

[0054]4) Rough rolling: carry out 6 times of rough rolling at 1090-1097°C, and control the reduction ratio of each pass at 32%;

[0055] 5) Cooling: After rough rolling, cool the rough rolled plate to 900-910°C at a cooling rate of 12°C / s;

[0056] 6) Finish rolling: carry out finish rolling according to 6 passes, control the interval time of each pass to 2.8 seconds, and the deformation amount of each pass is 35%;

[0057] 7) Air cooling: the air cooling time is 75 seconds;

[0058] 8) Perform rapid water coolin...

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Abstract

The invention relates to a method for producing graphitized free-machining steel from intermediate-carbon manganese-silicon steel, intermediate-carbon manganese-silicon-aluminum steel and the like. The method comprises the following steps: heating casting blanks; maintaining the temperature; cooling to 1050-1150 DEG C; roughly rolling: controlling the reduction percentage of each gate to be 20-40%; cooling to 850-1000 DEG C; carrying out precision rolling according to 4-6 gates; cooling in air; quickly cooling in water to room temperature; heating the precision rolling plate and maintaining the temperature; and cooling in air or cooling in a furnace to room temperature. By controlling the state of C atoms in steel and C content of austenite before tempering based on a process route of low-temperature rolling, relaxation and phase change, quenching and graphitization tempering, the invention converts all C atoms in the steel into graphite in a short time (5h). In the graphitized free-machining steel produced by the method, graphite grains in the organization are small in size and are uniform in distribution.

Description

technical field [0001] The invention relates to a production method of graphite steel, in particular to a method for producing graphitized free-cutting steel with medium-carbon-manganese-silicon steel or medium-carbon-manganese-silicon-aluminum steel. Background technique [0002] Graphite free-cutting steel is to change the carbon in the steel into graphite, and use the lubricating effect of graphite particles and the notch effect in the material (which can be regarded as a source of stress concentration) to improve the cutting performance of the material. Its machinability is better than that of lead free-cutting steel for mechanical structure, and has the same performance as that of lead, phosphorus and sulfur free-cutting steel, especially in the field of high-speed cutting. It also has the same performance as low-carbon steel Cold forgeability is a new steel that has both high cold forming and machinability and environmental friendliness. The free-cutting phase in grap...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C21D8/02
Inventor 尹云祥罗国华范植金刘吉斌方芳朱玉秀陈玮朱丛茂
Owner 武钢集团有限公司
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