利用YAG脉冲激光焊接系统对1 mm厚的1Cr17Ni2不锈钢薄板进行对接焊接试验,通过焊缝组织分析、拉伸测试和显微硬度测试,研究了离焦量对焊接接头组织与性能的影响。结果表明:采用激光对1Cr17Ni2薄钢板进行对接焊后,焊接接头出现了组织分区,母材区组织主要是铁素体和马氏体,热影响区组织为板条马氏体组织和少量呈带状分布的δ铁素体,而焊缝区组织则主要以马氏体为主;随着离焦量增加,焊缝熔深逐渐减小,熔宽先增大后减小,焊缝处的马氏体含量逐渐减少,接头的抗拉强度先增大后减小;焊缝区的硬度最大,母材区的硬度最小,热影响区的硬度介于两者之间;焊缝区的整体硬度随着离焦量的增大而减小;当离焦量为-5.5 mm时,热影响区中马氏体板条束群细小均匀,焊接成形质量好,接头的拉伸性能优良。

A YAG pulsed laser welding system was used to analyze the microstructure of welded 1Cr17Ni2 stainless steel plates, tensile properties and microhardness of the joints, and effects of different defocusing distances on the microstructure and properties of the welded 1Cr17Ni2 stainless steel plates. The results show that the laser self-melting butt welding in the 1Cr17Ni2 stainless steel plate weld shows a microstructure division. The main structure of the base material area comprises ferrite and martensite, the heat-affected area comprises lath martensite and a small amount of banded ferrite, and the weld area comprises mainly martensite. Weld penetration gradually decreases with increasing defocusing distance. Further, the weld width increases and subsequently decreases, the martensite content at the weld gradually decreases, and the joint's tensile strength increases and subsequently decreases. The joint hardness in descending order is weld zone > heat affected zone > base material zone. Thus, the joint's overall hardness decreases with increasing defocusing distance. When the defocusing distance is -5.5 mm, the martensite beam group in the heat affected zone is fine and even, the welding forming quality is good, and the joint has excellent tensile performance.