冲击载荷下50CrVA弹簧钢的多轴疲劳行为研究

Multiaxial Fatigue Behavior of 50CrVA Spring Steel under Impact Loading

本文用MTS 809拉-扭电液伺服材料试验机研究了50CrVA弹簧钢标准试样在冲击载荷下的多轴疲劳寿命,对试样的断口进行了宏微观观察。研究结果表明:冲击载荷会明显降低试样的寿命;试样的寿命随轴向拉力的增大而减小;宏观损伤方面,试样整个断口可见稳定扩展区、快速扩展区和瞬断区;稳定扩展区面积较小,快速扩展区磨损严重;与源区对侧存在一台阶,台阶与源区正对的位置存在一偏转角;台阶附近区域未出现明显的磨损,为瞬断区;微观损伤方面,裂纹源萌生于试样表面,稳定扩展区疲劳条带不明显,快速扩展区以剪切拉长韧窝和磨损形貌为主。

Multiaxial fatigue life of 50CrVA spring steel standard specimens under impact loading was studied with MTS 809 tension-torsion electro-hydraulic servo tester. The results show that impact loading can obviously reduce the specimens’ life. Specimens’ life decreases with the increasing of axial tension. In macroscopic damage aspect, slow, fast propagation and ifnal fracture zone can be observed throughout the specimen’s fracture. The area of slow propagation zone was small and fast propagation zone was worn badly. A step exits opposite the source, which is the ifnal fracture zone. There is a one-sided corner between step and the opposition of the source region. In microscopic damage aspect, fatigue sources initiate at the surface and fatigue stripes can’t be found easily on the slow propagation zone. Elongated dimples and wear are the main characteristics for the fast propagation zone.