Two batches of cracked 50CrVA springs are analyzed by means of fracture analysis, chemical composition analysis, microstructure analysis and hardness test. The fracture mode and mechanism are revealed as well as the effective improvement measures. The results indicate that the fracture mode of the two batches of springs are both delayed brittle fracture. The fracture mechanism of the first batch is attributed tohydrogen embrittlement. The risk of hydrogen embrittlement can be reduced by increasing the tempering temperature and reducing the pickling time. The fracture mechanism of the second batch of springs is cadmium embrittlement. Zinc plating process can be used to enhance the heat resistance temperature of the springs coating and decrease the risk of embrittlement caused by low melting point metal.
[1] 金双峰,程鹏,姜膺,等.弹簧的失效分析与预防技术[J].金属热处理,2010,36:410-144.JIN SH F,CHEN P,JIANG Y,et al. Spring failure analysis and prevention technology[J].HEAT TREATMENT OF METALS,2010,36:410-144.
[2] 孙云秋.弹簧腐蚀失效模式发生机制与预防[J].金属制品,2016,42(6):25-33.SUN Y Q. Corrosion failure mode happening mechanism and prevent of spring[J]. Metal Products,2016,42(6):25-33.
[3] 钟群鹏,赵子华.断口学[M].北京: 高等教育出版社,2006.ZHONG Q P,ZHAO Z H. Fractography[M].Beijing: Higher Education Press,2006.
[4] 张栋,钟培道,陶春虎,等,失效分析[M].北京: 国防工业出版社, 2004.ZHANG D,ZHONG P D,TAO CH H,et al. FAILURE ANALYSIS[M]. Beijing: National Defense Industry Press, 2004.
[5] 张宝东,侯锐,张兵,等.履带限位块开裂分析[J].失效分析及预防,2020,15(4)255-259.ZHANG B D,HOU R,ZHANG B,et al. Cracking analysis of stop blocks in caterpillar bands[J].Failure Analysis and Prevention,2020,15(4)255-259.
[6] 陈桂丰,李浩,周崎,等. 20Mn螺钉氢脆断裂分析[J]. 金属制品,2021,47(3):50-53.CHEN G F,LI H,ZHOU Q,et al. Analysis of hydrogen embrittlement fracture of 20Mn screw[J]. Metal Products,2021,47(3):50-53.
[7] 李金许,王伟,周耀,等. 汽车用先进高强钢的氢脆研究进展[J]. 金属学报,2020,56(4)444-458.LI J X,WANG W,ZHOU Y,et al. A Research status of hydrogen embrittlement for automotive advanced high-strength steels[J]. Acta Metallurgica Sinica,2020,56(4)444-458.
[8] 黄晋华,袁春,华小珍,等.飞机发电机花键轴断裂原因[J]. 腐蚀与防护,2015,36(5):493-496.HUANG J H,YUAN CH,HUA X ZH,et al. Fracture reason of castellated shaft in electric generator of an aircraft[J]. Corrosion & Protection,2015,36(5):493-496.
[9] 马丽莎,朱媛,刘贵芳.扭转弹簧镉脆断裂失效分析[J].电镀与精饰,2010,32(12):34-35.MA L SH,ZHU Y,LIU G F.Failure analysis of spiral spring cadmium embrittlement fracture[J]. Plating & Finishing,2010,32(12):34-35.