HEV变速器壳体开裂失效分析

Analysis of the Failure of HEV Transmission Housing Cracking failure

某混动车型变速器壳体测试过程开裂,对开裂的变速器壳体从化学成分、金相、硬度、夹杂物、针孔度、扫描电镜进行检测分析,发现开裂位置存在明显的针孔缺陷。同时扫描电镜检测微观形貌发现壳体开裂部位大量气孔富集形成密集孔洞。从优化整车总布置,优化壳体铸造工艺降低壳体针孔度等级,改善变速器产品机构提升壳体的铸造工艺性三方面提出了壳体改善措施。

The transmission shell of a hybrid vehicle was cracked during the test,and the cracked transmission shell was detected and analyzed from chemical composition,metallographic materiality,hardness,inclusions,pinhole degree and scanning electron microscopy.Obvious pinhole defects were found to exist in the cracking location.At the same time,scanning electron microscopy detected the micromorphology and found that a large number of pores in the cracked parts of the shell were enriched to form dense holes.Shell improvement measures are proposed from three aspects:optimizing the general layout of the whole vehicle,optimizing the shell casting process,reducing the pinhole level of the shell,improving the transmission product mechanism,and improving the casting processability of the shell.