表面碳势为1.1%C的渗碳硬化层内，临近外表面部位的枣核马氏体中会出现显微裂纹。
When carburized under high carbon potential (1. 1% C), microcracks tend to appear on the martensitic matrix near the outer surface of the layer.
试件的疲劳断裂模式全部为双面穿板断裂，疲劳裂纹起始于点焊热影响区搭接板内表面，沿板厚方向向外表面扩展；
Fatigue specimens cracked at two-sided through-thickness sheet, fatigue crack appeared initially in HAZ of inner surface of lap plates, along the thickness direction extended to outer surface;
试件的疲劳断裂模式全部为双面穿板断裂，疲劳裂纹起始于点焊热影响区搭接板内表面，沿板厚方向向外表面扩展；
Fatigue specimens cracked at two-sided through-thickness sheet, fatigue crack appeared initially in HAZ of inner surface of lap plates, along the thickness direction extended to outer surface;
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