关键词: 35CrMo, 电磁热, 疲劳裂纹, 应变能密度因子, 止裂

Abstract: A specimen of 35CrMo with fatigue crack is used to perform electromagnetic heating crack arrest experiment using a self-made ZL-2 super pulse current generation equipment. The crack tip melted after discharging, and the crack tip melt into a tiny ellipse, reducing the stress concentration. Comparing chemical ingredient in the oval region near crack tip with the base material after crack arresting, the content of Mn, Si, Mo raises, and the grains are refine , increasing the hardness and strength of materials around the crack tip. Specimens before and after discharging are tested by multi axial load fatigue testing machine under three-point bending fatigue load, and the results show that the average fatigue life of specimens after discharge are increased by 13%. Based on the coupled thermal-electrical theory, a numerical simulation method is proposed to study the temperature field. The strain energy density factor in the small region around crack tip is theoretically calculated. Because of the electrothermal stress intensity factor, the strain energy density factor is reduced that prevent the cracks expanding, and lays the foundation for the application of electromagnetic thermal arrest techniques.

Key words: 35CrMo, crack arrest, electromagnetic heating, fatigue crack, strain energy density factor