无钴马氏体时效钢电子束焊接接头组织与性能分析

对18Ni无Co马氏体时效钢进行了真空电子束焊接,用金相显微镜观察了焊接接头的组织形貌,并测定了焊缝区、热影响区、基体的显微硬度.结果表明,18Ni无Co马氏体时效钢组织为板条马氏体组织,材料焊接性能良好,焊缝区凝固组织为胞状树枝晶,熔合线附近热影响区晶粒发生了再结晶,晶粒长大明显.硬度分布有明显的规律性,焊缝区硬度最低,细晶区硬度最高,熔合线附近的热影响区,离熔合线越远,硬度值越高.在距熔合线2.5 mm处有一个马氏体与奥氏体两相混合的狭窄区域,硬度较其两侧有明显降低.

Microstructure and properties of electron beam welded joints of 18 Ni Co-free maraging steel

Electron beam welding was used to weld 18 Ni Cofree maraging steels.The microstructure of welded joints was investigated by optical microscopy, and the microhardness of weld metal, heat-affected zone and base material was tested.The results show that the microstructure of the base materials is lath martensite, and the microstructure of weld metal exhibits a typical cystiform-dendritic morphology.The region adjoining the weld metal was heated to high temperatures in the austenite phase before rapid cooling.EB welding heat input was high enough to lead to grain recrystallization.The softest region is weld seam, while the hardest is fine-grained zone. the microhardness in the heat-affected zone increases with the distance being away from fusion line.