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热积累对不同特征尺寸TA15钛合金 选区激光熔化组织的影响
Effect of Heat Accumulation during Selective Laser Melting on the Microstructure of TA15 Titanium Alloy with Different Geometry Characteristics
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- DOI:
- 作者:
- 王 前 1，2 ，秦翔阳 1，2 ，刘晓宇 1，2 ，周峻锋 1，2 ，陶思远 1，2 ，刘 帅 1
WANG Qian1,2, QIN Xiangyang1,2, LIU Xiaoyu1,2, ZHOU Junfeng1,2, TAO Siyuan1,2, LIU Shuai1,2, WANG Me
- 作者单位:
- 1.西北工业大学 金属高性能增材制造与创新设计工业和信息化部重点实验室，陕西 西安 710072；2. 西北工业大学 凝 固技术国家重点实验室，陕西 西安 710072
1. MIIT Key Laboratory of High Performance Additive Manufacturing and Innovative Design of Metal Structure, Northwestern Polytechnical University, Xi'an 710072, China; 2. State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi'an 710072, China
- 关键词:
- TA15 钛合金；选区激光熔化；热积累；组织形貌；马氏体分解
TA15 alloy; selective laser melting; heat accumulation; microstructure; in situ decomposition of martensite
- 摘要:
- 选区激光熔化成形的 TA15 钛合金塑性往往较差，通过热处理使沉积态试样中的马氏体转变为(α+β)层片
组织是提高其塑性的常用手段。 利用 SLM 过程独特的热历史可促使马氏体原位分解，实现一定程度的组织调控。 本文
采用选区激光熔化技术制备了圆柱体和倒锥体 TA15 合金试样，通过温度场模拟评估了试样的热积累程度，并分析了
其对试样组织演化的影响。 结果表明，圆柱体试样的晶粒组织为 β 柱状晶，其内部物相以 α′马氏体为主；倒锥体试样内
部存在更大程度的热积累，其 β 晶粒形貌存在向等轴晶转变的趋势，同时 α′马氏体原位分解形成(α+β)层片状组织。 热
积累导致的温度升高和在高温区间较长的停留时间是 α′马氏体发生原位分解的原因。
The plasticity of as-deposited TA15 titanium alloy prepared by selective laser melting (SLM) is often poor, and heat treatment is necessary to promote the decomposition of martensite into lamellar (α+β) laths so that the plasticity can be improved. During the SLM process, the unique thermal history can promote the in situ decomposition of martensite and adjust the as-deposited microstructure to a certain extent. In this study, TA15 alloy specimens with cylinder and inverted cone were prepared by selective laser melting. The heat accumulation of the specimens was analyzed based on temperature simulation results for the building process, and the effect of thermal accumulation on the microstructure of the specimens was analyzed with reference to the microstructure observations. The results show that the grain structure in the cylindrical specimen is β columnar grains composed of the martensite α′ phase. However, with the severe heat accumulation in the inverted cone specimen, transformation from β columnar to equiaxed β is observed, and in situ decomposition of the metastable martensite α′ occurs, leading to the formation of a lamella (α+β) structure. The extent, as well as the holding time of heat accumulation, are important factors for the in situ decomposition of the martensite α′ phase.