50CrVA弹簧断裂原因分析

50CrVA弹簧装配一段时间后发现断裂,后更换不同批次弹簧又发生断裂。对断裂弹簧进行断裂特征、组织观察分析,对硬度和镀层厚度进行测试。结果表明:存在表面镀层偏厚;弹簧的断裂性质为氢脆断裂;调查分析发现,断裂弹簧使用的表面处理槽液发生了改变,而工艺并未随之变化,致使在电镀过程中H的作用对弹簧影响较大,这是弹簧氢脆断裂的主要原因;此外,弹簧装配使用时不同轴导致应力集中,也对氢脆的发生有促进作用。工艺试验后,提出相应的改进措施,弹簧未发生断裂故障。

Analysis of 50 CrVA Spring Fracture

50CrVA springs fractured after assembling for a few days. Then different batches of springs were used but fracture occurred again. In order to find the failure cause of the springs, fracture characteristics observation, microstructure examination, hardness and coating thickness testing were carried out. The results show that the failure mode of the springs is hydrogen embrittlement fracture. The surface treatment bath solution for the broken springs had been newly improved and replaced, but the surface treatment process hadn’ t change accordingly, resulting in the increase of the effect of hydrogen during the electroplating process, which is the main reason for hydrogen embrittlement fracture of the springs. Besides, uncoaxial assembly and use of the springs promoted stress concentration and the occurrence of hydrogen embrittlement. After process test, appropriate improvement measures were proposed, and springs didn’ t fracture thereafter.