【摘要】 通过对钎焊失效件进行断裂裂纹的宏观分析及断口分析,确定了断裂发生的位置,并分析了断裂形式及疲劳裂纹萌生和扩展过程的特点。在对失效件裂纹的宏观观察中发现,断裂多发生在钎焊圆角根部,裂纹沿钎焊圆角根部萌生和扩展。对钎焊圆角表面微观形貌进行观察后发现,在钎焊圆角根部存在着连续分布的钎料瘤,容易引起局部应力集中,促进疲劳裂纹的萌生。在对失效件断口进行的分析中找到了疲劳断裂的典型特征——疲劳辉纹,有力地证明了失效模式为疲劳断裂。更多还原

【Abstract】 The position at fracture of the failure sample was examined by macrostructure and fracture analysis.The fracture form and the fatigue crack of initiation and expansion was analyzed.Most of fracture happened on the round angle root of joints,and the fracture initiated and expanded along with the round angle root.There existed some brazing filler metal knot,which was easy to cause the stress concentration and lead to the initiation of feature.Fracture analysis shows that the fatigue striation as the typical feature for the fatigue crack was found,which confirmed the failure mode offatigue break.更多还原