C300马氏体时效钢等离子弧焊接接头的组织与硬度

Keyhole plasma arc welding (K-PAW) was used to weld C300 maraging steel in solid-solution state, the microstructure observing and hardness analysis were carried out by optical microscopy transmission electron microscopy, scanning electron microscopy and hardness testing. The results indicate that, in order to avoid local concave it should be appropriate to consider using filler metal during welding C300 maraging steel by means of K-PAW, although good welded joint could be obtained without it. The welded joint with high symmetry could be divided into weld seam zone, solid-solution zone (including coarse grain zone and fine grain region), aging zone and base metal zone. Weld metal showed inverted horn morphology. The hardness peak of the joint was in the aging area, the width of the horizontal area of hardness curve was dependent on the width of the weld seam zone and solid-solution zone.The hardnesses of weld seam zone, solid-solution zone and base metal were the same. Crack morphology and huge difference composition contents of Ni, Mo, Ti and Co were found in aging zone.

采用穿孔型等离子弧(K-PAW)焊接方法对固溶态C300马氏体时效钢进行焊接, 并采用光学显微镜、透射电子显微镜、扫描电子显微镜以及硬度仪等对焊接接头进行了组织观察和硬度分析。结果表明: 采用K-PAW焊接可得到成形良好的焊接接头, 但为了避免局部凹陷现象, 应适当采用填充金属; 焊接接头具有高度对称性, 可分为焊缝区、固溶区(粗晶区和细晶区)、时效区以及母材区; 焊缝金属呈倒喇叭状形貌; 接头的硬度峰值出现在时效区, 硬度曲线上水平区域的宽度取决于焊缝区与固溶区的宽度; 焊缝、固溶区与母材的硬度基本相同; 在时效区发现皲裂形貌和镍、钼、钛和钴元素含量的差异。