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Austenite grain size refining control method for high-temperature carburized gear steel

An austenite grain, high-temperature carburizing technology is applied in the metallurgical field to achieve the effects of excellent processing performance and service performance, good austenite grain size stability, and a simple and easy control method for grain size refinement.

Inactive Publication Date: 2019-12-27
NANJING IRON & STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, there is no control method for refining the austenite grain size of CrNiMo series high-temperature carburizing gear steel produced by electric furnace process, especially the control method for refining austenite grain size by using AlN second phase, so it is necessary to propose a Al Fine Grain Method of CrNiMo Series High Temperature Carburizing Gear Steel Produced by Electric Furnace Process

Method used

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  • Austenite grain size refining control method for high-temperature carburized gear steel

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] Take the specification Bars for gear steel, including the following components by weight percentage: C: 0.20%, Mn: 0.75%, Si: 0.15%, P: 0.010%, S: 0.005%, Cr: 0.50%, Ni: 0.55%, Mo: 0.19%, Al: 0.025%, N: 0.018, and the rest are Fe and unavoidable impurities. Through EAF smelting, LF refining, VD vacuum degassing, continuous casting, slab slow cooling, primary heating, billet rolling, billet dephosphorization, secondary heat rolling heating, secondary heat rolling dephosphorization, final rolling, slow The gear steel prepared by cooling, straightening, peeling, ultrasonic flaw detection, and magnetic flux leakage flaw detection, the photo of the austenite grain after being corroded by saturated picric acid is as follows figure 1 shown.

[0019] Among them, EAF smelting: oxygen blowing slagging, control of electric furnace endpoint C 0.06%, P 0.007%, tapping temperature 1620°C, deoxidation and alloying operations during tapping.

[0020] LF refining: Add aluminum block...

Embodiment 2

[0030] Take the specification Bars for gear steel, including the following components by weight percentage: C: 0.23%, Mn: 0.90%, Si: 0.20%, P: 0.012%, S: 0.030%, Cr: 0.40%, Ni: 0.70%, Mo: 0.15%, Al: 0.040%, N: 0.015, and the rest are Fe and unavoidable impurities. After EAF smelting, LF refining, VD vacuum degassing, continuous casting, slab slow cooling, primary heating, billet rolling, billet dephosphorization, secondary heat rolling heating, secondary heat rolling dephosphorization, final rolling, slow The gear steel is prepared by cooling, straightening, peeling, ultrasonic flaw detection, and magnetic flux leakage flaw detection.

[0031] Among them, EAF smelting: oxygen blowing slagging, control of electric furnace end point C 0.07%, P 0.010%, tapping temperature 1600°C, deoxidation and alloying operations during tapping.

[0032] LF refining: the aluminum content in the molten steel is reduced to 0.010% by adding aluminum blocks, adding slagging materials for pre-sla...

Embodiment 3

[0042] Take the specification Bars for gear steel, including the following components by weight percentage: C: 0.18%, Mn: 0.70%, Si: 0.35%, P: 0.020%, S: 0.035%, Cr: 0.60%, Ni: 0.40%, Mo: 0.25%, Al: 0.044%, N: 0.014, and the rest are Fe and unavoidable impurities. After EAF smelting, LF refining, VD vacuum degassing, continuous casting, slab slow cooling, primary heating, billet rolling, billet dephosphorization, secondary heat rolling heating, secondary heat rolling dephosphorization, final rolling, slow The gear steel is prepared by cooling, straightening, peeling, ultrasonic flaw detection, and magnetic flux leakage flaw detection.

[0043] Among them, EAF smelting: oxygen blowing slagging, control of electric furnace end point C 0.10%, P 0.015%, tapping temperature 1650°C, deoxidation and alloying operations during tapping.

[0044] LF refining: Add aluminum blocks to make the aluminum content in molten steel 0.045%, add slagging materials for pre-slagging, and keep whit...

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Abstract

The invention discloses an austenite grain size refining control method for high-temperature carburized gear steel. The austenite grain size refining control method comprises the procedures of EAF smelting, LF refining, VD vacuum degassing, continuous casting, casting blank slow cooling, primary heating, cogging rolling, cogging dephosphorization, secondary rolling heating, secondary-fire rollingdephosphorization, finish rolling, slow cooling, straightening, peeling and ultrasonic and magnetic flux leakage combined flaw detection. The aluminum content of the procedures of LF refining and VD vacuum degassing is controlled to 0.010%-0.045%. The gear steel prepared with the austenite grain size refining control method has good austenite grain size control stability and can meet the control requirement of a high-temperature carburizing technology for the austenite grain size, thus a gear obtained after high-temperature carburizing has good processability and usability, and the austenite grain size refining control method is simple and easy to conduct.

Description

technical field [0001] The invention relates to the field of metallurgy, in particular to a method for controlling austenite grain size refinement of high-temperature carburized gear steel, and in particular to a method for controlling the grain size refinement of CrNiMo series high-temperature carburized gear steel. Background technique [0002] At present, in order to improve the production efficiency of the carburizing process, the gear industry at home and abroad generally raises the carburizing temperature to above 950°C, which leads to the appearance of large austenite grains after the carburizing heat treatment of the gear, which will eventually affect the processing performance and fatigue of the material. life. In recent years, in order to solve the problem of austenite grain size coarsening after high-temperature carburizing of gears, microalloys such as aluminum and niobium are added to form carbonitrides of aluminum or niobium to pin the grain boundaries, so as t...

Claims

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Application Information

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IPC IPC(8): C22C38/44C22C38/06C22C38/04C22C38/02C22C33/04C21D8/02
CPCC21D8/0205C21D8/0247C22C33/04C22C38/001C22C38/002C22C38/02C22C38/04C22C38/06C22C38/44
Inventor 黄术明李海洋王刚
Owner NANJING IRON & STEEL CO LTD
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