制扁工艺对51CrV4弹簧钢组织及性能的影响

Effects of Flat-end Rolling on Microstructure and Properties of the 51CrV4 Spring Steel

针对制扁区域在弹簧服役时易发生疲劳断裂失效的问题,在不同工艺环节对制扁加热部位的不同区域进行取样,分析各部位组织及性能随制扁及之后的热处理工艺的变化,分析制扁区域易失效的原因,并提出相应的解决方案。结果表明,制扁部位越靠近尖端的区域,制扁后组织越粗大,并向后续组织遗传,引起淬火后的马氏体粗大和回火组织的不均匀,导致相关区域强度与硬度不均匀。分析发现,组织粗化是由过热引起的,弹簧端部组织改进的关键是准确控制制扁加热的温度和保温时间。

Aiming at the problems in easily fatigue failure at flat-end region of spring during service processing,the samples were taken from different period of heat-treatment spring to analyze the reason leading to fatigue broken in the region of flat-end rolling,and a measure to improving the technique parameter of flat-end rolling was persented.The results show that spring microstructure is increasingly coarsened with decreasing in distance toward the end.And then,the quenched martensite is coarsened,and the tempered structure is tended to be nonuniform due to the heredity,so then the tensile strength and hardness present fluctuation considerably in this region.The coarsening of microstructure is attributed to by the over-heating before flat-end rolling.Hence,the heating temperature and the holding time need to be controlled precisely to improve the quality of spring end.