Cracking failure analysis of 18CrNiMo7-6 steel gear shaft

doi:10.13251/j.issn.0254-6051.2024.02.046

Abstract

Abstract: A gear shaft cracked during static standing after carburizing, quenching and tempering. In order to find out the failure mechanism of the gear shaft, macro and micro morphologies were observed and local chemical composition of the fracture surface was analyzed. In addition, the microstructure of the shaft near the fracture was examined, and the hardness and hydrogen content were tested. The results show that the failure mode of the gear shaft is delayed brittle cracking induced by hydrogen embrittlement. The crack initiated from the inside of the shaft and there is a large-size nonmetallic inclusion at the source zone, leading to greater stress concentration, which is the main cause for the hydrogen embrittlement cracking. Therefore, the material quality of the gear shafts should be strictly controlled, and nondestructive detection should be carried out to detect the large-size nonmetallic inclusions in the gear shafts so to prevent such failure.

Key words: gear shaft, 18CrNiMo7-6 steel, hydrogen embrittlement, nonmetallic inclusion

CLC Number:

TGl57

Zhang Bing, Mao Yimeng, Jiang Tao, Liu Xin. Cracking failure analysis of 18CrNiMo7-6 steel gear shaft[J]. Heat Treatment of Metals, 2024, 49(2): 297-300.

References

[1]屈鹏. 航空发动机主滑油泵齿轮轴断裂分析[J]. 失效分析与预防, 2012, 7(1): 38-42.
Qu Peng. Fracture analysis on gear wheel shaft of main oil pump in aero-engine[J]. Failure Analysis and Prevention, 2012, 7(1): 38-42.
[2]Xu L Q, Yu X K, Hou Z G. Analysis of the causes of driving gear shaft fractures in gear pumps[J]. Journal of Failure Analysis and Prevention, 2020, 20(1): 242-248.
[3]李平平, 陈凯敏, 吴建华, 等. 齿轮轴断裂原因分析及预防措施[J]. 金属热处理, 2016, 41(3): 207-209.
Li Pingping, Chen Kaimin, Wu Jianhua, et al. Fracture analysis of gear shaft and preventive measures[J]. Heat Treatment of Metals, 2016, 41(3): 207-209.
[4]冯志伟. CFM56-7B发动机起动机行星齿轮轴的失效分析与预防[J]. 航空维修与工程, 2020(3): 85-87.
Feng Zhiwei. Failure analysis and prevention of ATS gear shaft for CFM56-7B[J]. Aviation Maintenance and Engineering, 2020(3): 85-87.
[5]杨春, 朱衍勇, 钟振前, 等. 齿轮轴纵向延迟开裂原因分析[J]. 金属热处理, 2013, 38(8): 131-134.
Yang Chun, Zhu Yanyong, Zhong Zhenqian, et al. Failure analysis of longitudinal delayed cracking for gear shaft[J]. Heat Treatment of Metals, 2013, 38(8): 131-134.
[6]张兵, 石晓东, 侯锐, 等. 齿轮轴开裂原因分析[J]. 失效分析与预防, 2022, 17(2): 124-128.
Zhang Bing, Shi Xiaodong, Hou Rui, et al. Cracking cause analysis of gear shaft[J]. Failure Analysis and Prevention, 2022, 17(2): 124-128.
[7]Brahimi S V, Yue S, Sriraman K R. Alloy and composition dependence of hydrogen embrittlement susceptibility in high-strength steel fasteners[J]. Philosophical Transactions of the Royal Society A, 2017, 375: 20160407-20160426.
[8]张宝东, 侯锐, 张兵, 等. 履带限位块开裂分析[J]. 失效分析与预防, 2020, 15(4): 255-259.
Zhang Baodong, Hou Rui, Zhang Bing, et al. Cracking analysis of stop blocks in caterpillar bands[J]. Failure Analysis and Prevention, 2020, 15(4): 255-259.
[9]张栋, 钟培道, 陶春虎, 等. 失效分析[M]. 北京: 国防工业出版社, 2008: 198-199.
[10]Li X F, Zhang J, Ma M M, et al. Effect of shot peening on hydrogen embrittlement of high strength steel[J]. International Journal of Minerals, Metallurgy and Materials, 2016, 23(6): 667-675.
[11]陈德华, 藤鲁湘, 李光瑾. 渗碳淬硬层残余应力的分布特征[J]. 热处理, 2011, 26(2): 65-71.
Chen Dehua, Teng Luxiang, Li Guangjin. Distribution characteristics of residual stress in carburized and gardened case[J]. Heat Treatment, 2011, 26(2): 65-71.
[12]Murakami Y, Kanezaki T, Sofronis P. Hydrogen embrittlement of high strength steels: Determination of the threshold stress intensity for small cracks nucleating at nonmetallic inclusions[J]. Engineering Fracture Mechanics, 2013, 97(1): 227-243.
[13]Fujita S, Murakami Y. A new inclusion rating method by positive use of hydrogen embrittlement phenomenon[J]. Metallurgical and Materials Transactions A, 2013, 44(1): 303-322.

[1]	Liu Ziquan, Li Kejian, Zhang Longzhu, Li Shouhua, Feng Yi, Cao Pengjun. Microstructure and properties of ultra-high strength martensitic steel prepared by ultra-fast cooling process [J]. Heat Treatment of Metals, 2024, 49(2): 32-39.
[2]	Zhang Lei, Mi Pei, Ma Chunliang, Sun Yongpeng. Cause analysis of carburizing quenching cracks of sun gear [J]. Heat Treatment of Metals, 2023, 48(9): 293-296.
[3]	Chen Shengchao, Chen Yesheng, Rong Zeyu, Wang Hongwei, Xu Hongxiang, Zhao Shaofu, Guo Jingqiang. Cracking failure analysis on high-speed intermediate shaft gear [J]. Heat Treatment of Metals, 2023, 48(7): 287-291.
[4]	Lü Huyue, Chen Xuyang, Cong Peiwu, Lu Wenlin, Du Chunhui. High-pressure gas quenching test of automobile gears and optimization of quenching chamber structure [J]. Heat Treatment of Metals, 2023, 48(6): 264-269.
[5]	Lü Huyue, Chen Xuyang, Cong Peiwu, Lu Wenlin, Du Chunhui, Hu Fengjiao. Second phase precipitation strengthening process of vacuum carburizing and quenching [J]. Heat Treatment of Metals, 2023, 48(5): 236-240.
[6]	Cai Zhenxiang, Cheng Xiaoying, Peng Hao, Li Xiaoliang, Wang Zhaofeng. Effect of tempering temperature on hydrogen behavior of Nb-containing HSLA steel [J]. Heat Treatment of Metals, 2023, 48(4): 45-52.
[7]	Wang Zhaofeng, Cheng Xiaoying, Li Xiaoliang, Peng Hao, Cai Zhenxiang. Effect of tempering temperature on hydrogen embrittlement sensitivity of a high strength low alloy steel containing V and Nb [J]. Heat Treatment of Metals, 2023, 48(3): 12-18.
[8]	Yin Xiaojian, Xu Yongchun, Zhang Bing, Feng Derong, Sun Xiaojun, Zhang Qinying. Fracture failure analysis of cover plate bolt of aircraft [J]. Heat Treatment of Metals, 2023, 48(10): 297-301.
[9]	Zheng Hong, Lin Wenqin, Yang Yuanxi, Xu Xinjie, Deng Feng, Wu Jiaxin, Jiang Hongjun. Fracture causes analysis of front lifting lug of 30CrMnSiA alloy [J]. Heat Treatment of Metals, 2022, 47(8): 292-295.
[10]	Zhang Minghao, Han Haoyuan, Xu Yueming, Li Qiao, Gao Zhi, Zhou Leyu. Carbide precipitation law in vacuum carburized 18CrNiMo7-6 steel [J]. Heat Treatment of Metals, 2022, 47(5): 171-176.
[11]	Chen Qiang, Chen Linfang, Yang Minghua. High temperature carburizing process of 18CrNiMo7-6 steel in controlled atmosphere [J]. Heat Treatment of Metals, 2022, 47(4): 231-239.
[12]	Fang Xiurong, Liu Liu, Xu Huihui, Gao Yang. Effect of pre-heat treatment before carburizing on distortion of gear shaft made of 17CrNiMo6 steel [J]. Heat Treatment of Metals, 2022, 47(3): 113-118.
[13]	Fu Siyu, Du Yu, Huang Zhiyuan, Lu Jianing, Du Linxiu. Effect of microstructure on hydrogen diffusion behavior of GCr15 bearing steel [J]. Heat Treatment of Metals, 2022, 47(12): 175-180.
[14]	Zheng Kai, Zhong Zhenqian, Cao Wenquan, Lin Shuangping, Liu Ming. Cracking failure analysis of 18CrNiMo7-6 steel gear after heat treatment [J]. Heat Treatment of Metals, 2022, 47(12): 275-280.
[15]	Wang Chunyan, Zhang Fa, Jie Ruihua, Wang Chunmei. Typical fracture and cause analysis of 35CrMnSiA ultra-high strength steel [J]. Heat Treatment of Metals, 2022, 47(12): 284-288.