中文摘要：

采用钨极氩弧焊对SPA-H钢与304不锈钢进行异种钢焊接,分析测试了不同焊接电流下焊接接头的显微组织、显微硬度和拉伸性能,研究了焊接电流对焊接接头组织及性能的影响。结果表明,随着焊接电流的增加,焊缝组织从定向生长的胞状晶和树枝晶到细化的胞状晶和树枝晶,再到粗大的等轴晶变化;SPA-H母材与焊缝之间存在明显的熔合线,而且随着焊接电流增加,熔合线由窄变宽;焊接接头中的硬度峰值都出现在焊缝区,电流为70 A时焊接接头焊缝和304侧热影响区的硬度值最高,但SPA-H侧热影响区的显微硬度显著低于焊缝区的显微硬度;电流为70 A的试样接头抗拉强度均高于60、80 A的焊接接头,60 A的试样接头抗拉强度和伸长率最低;三种焊接电流下的焊接接头抗拉强度均远高于母材,焊缝满足强度要求。

英文摘要：

The dissimilar steel welding between SPA-H steel and 304 stainless steel was carried out by using tungsten inert gas（TIG ） welding. The mierostructure, microhardness and tensile properties of the welded joints under different welding currents were tested and analyzed, and the influence of welding current on the microstructure and properties of welded joint was studied. The results, show that with the increase of welding current, the microstructure of welding seam firstly changes from the directionaUy grown cellular crystal and dendrites to the refined cellular crystals and dendrites, and then changes to coarse equiaxial crystals. There is obvious fusion line between SPA-H base metal and welding seam, and the fusion line changes from narrow to wide with the increase of welding current. The hardness peak values of welded joint appear in the weld zone. When the current is 70 A, the hardness of weld zone and the heat affected zone at the 304 side is highr than that of welded joints under 60, 80 A. The microhardness of heat affected zone at the side of SPA-H is significantly lower than that of weld zone. The tensile strength of the sample under the welding current of 70 A is the highest, and the tensile strength and the elongation of the sample under 60 A are the smallest. The tensile strength of welded joints under the three welding currents is much higher than that of base metal, and the welding seam meets the strength requirement.