C300 穿孔型等离子弧焊接焊缝结晶裂纹的研究

采用光学显微镜、扫描电子显微镜以及Thermal-calc 计算等方法分析了马氏体时效钢(C300) 穿
孔型等离子弧焊接(Keyhole-Plasma Arc Welding, K-PAW)过程中结晶裂纹的成因及形貌。研究认为,C300 虽
然具有良好的焊接性,但也会产生结晶裂纹。本试验条件下,影响高纯净C300 产生结晶裂纹的主要因素是应
变—温度增长速率,提高预热温度和增加线能量有利于降低结晶裂纹倾向。焊接热源对母材的预热作用有利
于已形成结晶裂纹的逐步止裂。具有凸形表面的焊缝以及细小等轴晶的焊缝的结晶裂纹倾向较小。

Investigation on Solidification Cracking of C300 Keyhole Plasma Arc Welding

This study was undertaken to analysis the causes and morphology of Keyhole-Plasma Arc Welding
(K-PAW) solidification cracking of Maraging steel (C300) by means of optical microscopy (OM), scanning electron
microscopy (SEM) and Thermal-cale. The results indicated that although C300 has good weldability, it can also produce
solidification cracking. In our experimental condition, the dominant factor which induces solidification cracking
of high purity C300 was the strain-temperature growth rate. Improving the preheating temperature and increasing welding
heat input could reduce solidification cracking tendency. The preheating effect of heat source to the base metal
step-by-step was propitious to the arrest of solidification cracking. The solidification cracking tendency of weld metal
which has convex surface or fine equiaxed grains would be decreased.