变速器换挡固定块烧结钎焊失效分析

Failure analysis of sinter-brazing of transmission shift fixing block

采用宏观观察、金相检验、力学性能试验、扫描电子显微镜分析和能谱分析等方法,对某平台烧结钎焊换挡固定块钎缝失效原因进行了分析。结果表明,由于烧结工艺和母材的影响,生产过程中存在烧结后钎料流失到母材表面,热处理后钎料过多熔渗进入母材,从而导致钎缝中存在的钎料不足;同时存在热处理后的变形现象,两者均未形成钎缝圆角,钎缝中冶金反应不足,接头有效承载面积小,强度较低。建议严格控制烧结钎焊零件生产过程,改善钎焊工艺,提高成品率。

Failure reasons of brazing seam of sinter-brazing shift fixed block in a certain platform were analyzed by means of macroscopic observation,metallographic examination,mechanical property test,scanning electron microscopy analysis and energy spectrum analysis.The results showed that due to influence of sintering process and base metal,there was a loss of brazing filler metal to the surface of base metal after sintering during production process,and excessive infiltration of brazing filler metal into base metal after heat treatment,which resulted in insufficient brazing filler metal in brazed joint.At the same time,there was deformation phenomenon after heat treatment.Both of them did not form fillet of brazed joint,metallurgical reaction to brazed joint was insufficient,and effective bearing area of brazed joint was small and the strength was low.It was suggested to control production process of sinter-brazing parts strictly,improve brazing process and increase yield of finished products.