Abstract：The ductile iron planet carrier fractured in the process of use, the location of the fracture is between two planet holes. Through the comprehensive analysis of the planet carrier by means of macro analysis, micro analysis, mechanical properties and other analysis, it is determined that the fracture mode of the planet carrier is fatigue fracture, the fatigue expansion is sufficient, no phenomenon of excessive local force was found, and there are shrinkage porosity defects at the cracking position. The existence of shrinkage defects cut off the internal continuity of the material, resulting in the reduction of the strength of the fracture site, make the parts crack before reaching the fatigue strength of the material, especially the parts subjected to periodic alternating load. The shrinkage is serious and produce prematurely extending to the surface of the parts, so that the stress concentration coefficient at the defect on the surface of the part increases sharply, fatigue cracks resulting in early fatigue failure of parts.
刘岩, 李雪峰, 郭海霞, 袁晓冬, 王世宁. 球墨铸铁行星架断裂原因分析[J]. 物理测试, 2023, 41(1): 35-39.
LIU Yan, LI Xuefeng, GUO Haixia, YUAN Xiaodong, WANG Shining. Fracture cause analysis of ductile iron planet carrier. PHYSICS EXAMINATION AND TESTING, 2023, 41(1): 35-39.
2023, Vol. 41 
