热处理对激光沉积Ti60A高温钛合金组织及性能的影响
Effect of Heat Treatment on Microstructures and Mechanical Properties of Laser Melting Deposited High Temperature Titanium Alloy Ti60A
马陶然,方艳丽，王华明
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作者单位：北京航空航天大学
中文关键字：高温钛合金；激光熔化沉积；显微组织；力学性能
英文关键字：high temperature titanium alloy; laser melting deposition; microstructures; mechanical properties
中文摘要：采用激光熔化沉积方式成形了近α高温钛合金Ti60A厚壁板材，分析了凝固组织形成机理。结果表明，激光沉积Ti60A合金的凝固组织由沿沉积方向定向生长的柱状晶组成，晶内是均匀分布的细小网篮组织。在α+β两相区上部和α单相区进行双重退火热处理，系统研究了双重退火温度对显微组织和力学性能的影响规律。结果表明，合金经过双重退火热处理后，获得了具有“蟹爪”状初生α相和细片层状β转变组织的“特殊双态组织”，同时降低第一步退火温度能够消除连续晶界α相。因片层间β相具有良好的协调变形能力，双重退火处理可以提高合金塑性。
英文摘要：Laser melting deposition was utilized to shape the near-alpha high temperature titanium alloy Ti60A thick plate. The forming mechanism of solidified structures was investigated. Laser deposited Ti60A alloy consists of columnar grains growing directionally along the deposited direction, and fine basket weave transformed β phase are uniformly distributed within the grain. Microstructures and mechanical properties of the alloy have been systematically studied while double-annealing treatment was applied in upper α+β phase field and α phase. It was found that double annealing for the alloy would lead to a unique and stable bi-model microstructure consisting of crab-claw-like primary α phase and thin lamellar transformed β phase. Moreover, decreasing the annealing temperature of first step could diminish continuous grain boundary α phase. As the remaining β phase, produced by double annealing, displayed better plastic performance during tensile tests, the plastic property of the alloy improved.