激光选区熔化Hastelloy-X合金的显微组织与拉伸性能

Microstructure and Tensile Properties of Hastelloy-X Alloy Prepared by Selective Laser Melting

采用激光选区熔化技术制备了Hastelloy-X合金(沉积态),并依次进行了热等静压和热处理,研究了不同处理后合金的显微组织和室温拉伸性能。结果表明:当线能量为98J·m^(-1)时,沉积态Hastelloy-X合金组织中存在气孔、未熔粉等缺陷和熔池界、枝晶等亚结构,随着线能量的增大,合金的相对密度提高,缺陷数量减少;经热等静压处理后,组织由等轴晶和网状碳化物组成,经热等静压+热处理后,部分网状碳化物溶解并呈弥散分布,晶内析出细小的第二相;沉积态合金的断裂方式为脆性断裂,经热等静压处理后,合金的塑性提高,断口呈二次裂纹+韧窝的混合型形貌,经热等静压+热处理后,合金的塑性进一步提高,室温拉伸性能优于锻件的标准指标,断口呈以破裂碳化物为韧窝中心的韧性断裂形貌。

Hastelloy-X alloy（as-diposited state）was prepared by selective laser melting,and was treated by thermal isostatic pressure and heat treatments in sequence.The microstructure and tensile properties at room temperature of the alloy after different treatment were investigated.The results show that defects of pores and unmelting powder and sub-structures of melting pool boundaries and dendrites were formed in as-deposited HastelloyX alloy at linear energy of 98 J·m^-1;with the increase of linear energy,the relative density of the alloy increased and defects amount decreased.After thermal isostatic pressure treatment,the microstructure consisted of equiaxial grains and network carbides.After thermal isostatic pressure and heat treatment,apart of network carbides dissolved and distributed evenly,and the fine second phases precipitated in grains.The fracture mode of as-deposited alloy was brittle fracture.After thermal isostatic pressure treatment,the plasticity of the alloy was improved and the fracture presented a mixed morphology with secondary cracks and dimples.After thermal isostatic pressure and heat treatment,the plasticity was further improved,the room-temperature tensile properties was better than the standard index of forging parts,and the fracture presented the ductile fracture morphology with the dimple center of fractured carbides.