基于CMT的电弧熔丝增材Ti-6Al-3Nb-2Zr-1Mo合金的组织与性能

采用基于冷金属过渡的电弧熔丝增材方法(CMT-WAAM)制备了Ti-6Al-3Nb-2Zr-1Mo合金试样，研究了CMT-WAAM Ti6321合金显微组织、力学性能及其各向异性. 结果表明，CMT-WAAM Ti6321合金显微组织由不规则的多边形原始β晶和晶界α相组成，CMT脉冲工艺(CMT+P)能够有效细化晶粒，组织中没有发现贯穿式的柱状晶，且未发现马氏体.CMT-WAAM Ti6321合金x向和z向的室温抗拉强度达到同级别锻件标准，断口形式均为典型的韧性断裂.成形组织中没有明显的织构存在，拉伸强度的各向异性也不明显，组织中的气孔导致z向的断后伸长率低与x向. x向和z向冲击韧性均不低于65 J，能够满足船用钛合金结构件的需求，冲击断口中存在大量的撕裂型韧窝，为典型的韧性断裂.

Microstructures and mechanical properties of Ti-6Al-3Nb-2Zr-1Mo alloy fabricated by CMT-wire arc additive manufacturing

The microstructure, mechanical properties and anisotropy of Ti-6Al-3Nb-2Zr-1Mo alloy made by CMT-Wire Arc additive manufacturing(CMT-WAAM) were studied. The as-built microstructures exhibit irregular polygons prior β and grain boundary α. This technology can refine the grains, and no columnar prior β grain morphology is observed. No martensite phase was discovered. The tensile strength in both directions have reached the standard requirements of the same level forging. No obvious texture is observed, and the anisotropy in tensile behavior is not obvious. There is no obvious texture and anisotropy in the manufactured structure. The ductility in transverse specimens was limited by the presence of lack-of-fusion porosity. The impact toughness of x and z direction is not less than 65 J. The impact fracture is typical ductile fracture,which consists of a large number of dimples.