【摘要】 应用ΔJ参数和扫描电镜 (SEM)方法 ,研究了 30 9L和 347L不锈钢堆焊层短裂纹的低频疲劳特性。并用da/dN =C(ΔJ) n 计算了裂纹扩展速率和门槛值。发现裂纹扩展行为可分为三个阶段 ,并有三个方程与之对应。经计算得到堆焊态 347L和 30 9L奥氏体不锈钢裂纹扩展门槛值 (ΔJth)分别为 355× 10 - 6 MN/m和 196× 10 - 6 MN/m。SEM断口分析表明 ,三个阶段的短裂纹扩展特性各不相同更多还原

【Abstract】 The investigation on the stack welding layers of 309 L and 347 L steel for low frequency fatigue with short\|crack indicates that the  d a/ d N- Δ J relation consists of three stages relating to three equations with the model of  d a/ d N=C( Δ J)\+n,respectively, on which the calculation of threshold value  Δ J\-\{ th \}≈355×10\+\{-6\} MN/m  for 347 L steel and  Δ J\-\{ th \}≈196×10\+\{-6\} MN/m  for 309 L steel is based.In addition, the different crack propagation mechanism is observed in three propagation stages after fracture analysis by SEM.更多还原