Microstructure and mechanical properties of TC4-DT produced by laser wire-feed additive manufacturing
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摘要: 激光熔丝增材制造技术在航空航天、海工船舶等领域应用前景广阔。针对TC4-DT材料,在初步优化的工艺参数下,通过激光熔丝增材制造技术制备金属试样,并对试样进行固溶-强化热处理,研究激光熔丝沉积态及热处理态的微观组织、缺陷及室温拉伸力学性能。研究发现,激光熔丝TC4-DT成形态组织为粗大的柱状晶及针状αʹ马氏体,热处理后转变为等轴晶与柱状晶的双相组织,马氏体分解为针状α+β双相组织,固溶-强化热处理后拉伸力学性能与锻件水平相当。Abstract: Laser wire-feed metal additive manufacturing technology has a wide application prospect in aerospace, marine engineering and shipbuilding. In this paper, TC4-DT samples were prepared by the laser wire-feed additive manufacturing technology combined with solution strengthening heat treatment method, based on the initial optimized process parameters. The microstructure, defects and room temperature tensile mechanical properties of the samples at as-deposited state and heat-treated state were respectively studied. It is found that the morphology of as-deposited TC4-DT is composed of columnar grains and acicular αʹ martensite. After solution strengthening heat treatment, equiaxed and columnar dual phase structure is formed, and αʹ martensite is decomposed into acicular structure of α+β. The tensile mechanical properties after heat treatment are equivalent to those of forgings.
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表 1 TC4-DT丝材化学成分
Table 1. The chemical composition of TC4-DT wire
% C V Al Fe Ti H N O 0.013 4.03 6.33 0.049 90.14 0.0055 0.006 0.034 表 2 激光熔丝试验工艺参数
Table 2. Processing parameters of laser wire-feed additive manufacturing
扫描速度vs/(mm·s−1) 送丝速度vf/(mm·s−1) 功率P/kW 离焦量H/mm 光丝距L/mm 送丝角α/(°) 搭接率/% 10 20 3.0 50 0 30 50 表 3 TC4-DT钛合金激光熔丝沉积态、热处理态与(GB/T 25137—2010)标准中TC4 ELI退火态合金棒室温拉伸数据对比
Table 3. Comparison of tensile data at room temperature of as-deposited, heat-treated laser fusing additive manufactured TC4-DT titanium alloy and TC4 ELI annealed alloy in GB/T 25137—2010 standard
试样 Rm/MPa Rp0.2/MPa A/% 沉积态 976 901 6 热处理态 1 029 894 9.5 TC4 ELI锻件(GB/T 25137—2010) 828 759 10 -
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