Influence of heat treatment on microstructures and mechanical properties of K447A cladding layers obtained by laser solid forming
Influence of heat treatment on microstructures and mechanical properties of K447A cladding layers obtained by laser solid forming
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DOI：
10.1016/j.jallcom.2019.03.136
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发表时间：
2019-06
影响因子：
6.2
通讯作者：
Zhenlin Zhang;Yue Zhao;J. Shan;A. Wu;H. Gu;Xin Tang
中科院分区：
文献类型：
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作者：
Zhenlin Zhang;Yue Zhao;J. Shan;A. Wu;H. Gu;Xin Tang
采用激光增材制造技术，采用Ti和Nb混合粉末原位制备了Ti-26Nb合金。在650 ° C至925 ° C的温度范围内对合金进行退火，并研究退火温度对显微组织和力学性能的影响。已经发现，在本条件下获得的沉积态合金的显微组织的特征在于在构建方向上具有相对强的纤维织构的柱状的先前β晶粒。<001>沉积态合金具有极高的强度，其极限抗拉强度和屈服强度分别约为799 MPa和768 MPa。退火温度对合金的显微组织和力学性能有显着影响。退火处理可以促进未熔Nb颗粒的溶解，消除Nb在椭圆形晶界处的显微偏析，同时增大合金的晶粒尺寸。随着退火温度的升高，合金的强度降低，塑性提高。在850 ° C下退火的合金表现出强度和延展性的平衡。
In the present work, a Ti–26Nb alloy was elaborated in situ by laser additive manufacturing (LAM) with Ti and Nb mixed powders. The alloys were annealed at temperatures ranging from 650 °C to 925 °C, and the effects of the annealing temperature on the microstructure and mechanical properties were investigated. It has been found that the microstructure of the as-deposited alloy obtained in the present conditions is characterized by columnar prior β grains with a relatively strong <001> fiber texture in the build direction. The as-deposited alloy exhibits extremely high strength, and its ultimate tensile strength and yield strength are about 799 MPa and 768 MPa, respectively. The annealing temperature has significant effects on the microstructure and mechanical properties of the alloys. Annealing treatment can promote the dissolution of unmelted Nb particles and eliminate the micro-segregation of Nb at the elliptical-shaped grain boundaries, while increasing the grain size of the alloy. With an increase in annealing temperature, the strength of the alloy decreases but the ductility increases. The alloy annealed at 850 °C exhibits a balance of strength and ductility.