以5B71 合金焊丝为填充材料,采用钨极惰性气体保护(TIG)焊接工艺对1.2 mm 厚激光选区熔化技术(Selective Laser Melting,SLM)制备的板材进行焊接,对焊接接头的显微组织演变及细化特征进行研究.结果表明:采用合理的TIG焊接参数焊接的SLM增材Al-Mg-Sc-Zr试件,焊缝正面靠近表面位置和焊接接头熔合线位置,分布着数量较多的气孔,最大直径达到0.3 mm,焊接接头熔合线附近的气孔夹渣数量和尺寸大小均大于母材,焊缝内部的气孔夹渣数量少于其他区域;焊缝中Sc和Zr微合金元素改善了组织晶粒大小,为等轴晶;熔合线的晶粒为柱状晶,柱状晶晶粒尺寸约为80～100 μm.焊缝断口呈现脆韧性复合断裂形貌,断裂面气孔密集,未发现明显的剪切唇,气孔周围断面存在明显韧窝组织,部分韧窝内发现强化相颗粒,气孔内部存在尖锐裂纹源.
Microstructure and Performance of Selective Laser Melting Formed Al-Mg-Sc-Zr Alloy TIG Welding
A selective laser melting(SLM)formed 5B70 aluminum alloy sheet with 1.2 mm thickness was welded by tungsten inert gas(TIG)welding with 5B71 filler wire.The microstructure evolution and refinement characteristics of the welded joints were investigated.The research results indicated that,for the SLM Al-Mg-Sc-Zr sheets by adopting reasonable TIG welding parameters,a lots of pores were distributed in the joints nearing the reverse side and the bond line,in which the largest pore was 0.3 mm in diameter.Compared with the parent material,the material nearing the bond line had more pores and slags as well as larger pores and slags.Less pores and slags was found in joints than the other areas.The Sc and Zr elements in the joints could improve the micro-structure,resulting in equiaxed grains.The grains in the bond line were columnar crystal,with a diameter of 80～100 μm.A mixed fracture characteristics of the tough and brittle was noted on fractograph of the weld fracture surface,in which some distinctive dimples were found among the pore fracture surface,some strengthening phase particles were found in partial dimple,sharpened cracks were found in pore internal.
万方数据
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