Microstructure and hardenability of vanadium microalloyed high temperature carburized SCM420H gear steel

Liu Nianfu; Hu Tao; Tian Qianren; Wang Gaofeng; Fu Jianxun

doi:10.7513/j.issn.1004-7638.2022.03.020

Volume 43 Issue 3

Jun. 2022

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Liu Nianfu, Hu Tao, Tian Qianren, Wang Gaofeng, Fu Jianxun. Microstructure and hardenability of vanadium microalloyed high temperature carburized SCM420H gear steel[J]. IRON STEEL VANADIUM TITANIUM, 2022, 43(3): 125-131. doi: 10.7513/j.issn.1004-7638.2022.03.020

Citation:

Liu Nianfu, Hu Tao, Tian Qianren, Wang Gaofeng, Fu Jianxun. Microstructure and hardenability of vanadium microalloyed high temperature carburized SCM420H gear steel[J]. IRON STEEL VANADIUM TITANIUM, 2022, 43(3): 125-131. doi: 10.7513/j.issn.1004-7638.2022.03.020

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Microstructure and hardenability of vanadium microalloyed high temperature carburized SCM420H gear steel

doi: 10.7513/j.issn.1004-7638.2022.03.020

Liu Nianfu^{1, 2
,},
Hu Tao¹,
Tian Qianren¹,
Wang Gaofeng¹,
Fu Jianxun^{1
,
,}

1.
School of Materials Science and Engineering,Shanghai University，Center for Advanced Solidification Technology (CAST), State Key Laboratory of Advanced Special Steel, Shanghai 200444, China
2.
Baowu JFE Special Steel Co., Ltd., Shaoguan 512123, Guangdong, China

Received Date: 2021-12-08
Publish Date: 2022-06-30

Abstract

Abstract

The high-temperature carburized SCM420H gear steel was modified with vanadium microalloying, and the structure and hardenability of the steel were studied. The results show that the V and N contents in SCM420H gear steel should be controlled within the range of 0.03%~0.05% and 0.012%~0.018%, respectively. MN (M=Ti,V) precipitates at 966 ℃ and transforms into M(C,N) at 559 ℃. The mass percentage of M(C,N) approximates 0.049%. The heating temperature is controlled at 1200 ℃±20 ℃, and the heating time is controlled within 120 minutes in the preheating section (from room temperature to about 850 ℃). After high temperature carburizing and holding at 940~980℃ for 6 hours, the banded structure of bar steel is controlled at 1.5 to 2 level, and the austenite grain size is at ASTM 7.5 to 8. M (C,N) is mainly nano-seized spherical V (C,N) which can pin grain boundaries and refine austenite grains. Under the following casting parameters: the electromagnetic stirring intensity parameters of the continuous casting mold are adjusted to 150 A, 2.5 Hz, the casting speed is at 0.85 m/min, the casting superheat is 15 to 30 ℃, the deviation value of carbon content can be controlled at 0.01% which is beneficial to narrowing control of hardenability. After vanadium microalloying, the maximum hardenability value（HRC） of the sample is 37, the minimum is 35, and the hardenability bandwidth（HRC）is not greater than 3.
- gear steel,
- SCM420H,
- vanadium microalloying,
- high-temperature carburizing,
- hardenability

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References(16)

References

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