热等静压对激光直接沉积Ti60 合金组织与拉伸性能的影响

利用激光直接沉积技术成形Ti60 合金,研究热等静压双重退火对激光直接沉积Ti60 合金缺陷、组织及拉伸性能的影响。结果表明:激光直接沉积Ti60 合金存在气孔和未熔合两种缺陷,经热等静压处理后,气孔和尺寸较小的未熔合缺陷消除;沉积态试样底部和中部为柱状晶,顶部为等轴晶,显微组织为魏氏组织,由板条和板条间组成;经热等静压双重退火处理后,晶界消融,大部分原始晶界消失,板条粗化,长宽比减小,显微组织变为网篮组织;与锻件相比,沉积态试样拉伸强度较高,塑性较低,经热等静压双重退火处理后,其塑性达到了锻件标准。

Effects of hot isostatic pressing on microstructure and tensile properties of direct laser deposited Ti60 alloys

Ti60 alloys were fabricated by using direct laser deposition (DLD) technology and it was studied that the effects of hot isostatic pressing (HIP) on defects, microstructure and tensile properties of the DLD Ti60 alloys. The results show that there are two typical kinds of defects in the DLD Ti60 alloys, which are pores and lack of fusion. After HIP treatment, pores and the small size of lack of fusion are eliminated. There are columnar crystals at the bottom and the middle of the as-deposited specimens, but at the top of the specimens are equiaxed grains. The microstructure is widmanstatten structure, which is composed of alpha laths and beta between the laths. After HIP and double annealing treatment, the grain boundary alpha melting, the most of the original beta grain boundaries disappear, alpha laths coarsening, the length-width ratio decreases, and the microstructure becomes basket-weave microstructure. Compared with the forgings, the as-deposited specimens have a high tensile strength with a low plasticity, after HIP and double annealing treatment, the plasticity of the as-deposited specimens exceeds the standards of the forgings.