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β锻造与热处理对粉末TC4钛合金组织与力学性能的影响

Effect of β forging and heat treatment on the microstructure and mechanical properties of powder TC4 titanium alloy

  • 摘要: 低成本粉末无压烧结钛合金构件的力学性能,尤其是疲劳性能,通常不及锻造钛合金,而后续热加工可有效提升其力学性能。本文研究了β锻造与固溶时效热处理对粉末无压烧结TC4钛合金显微组织及力学性能的影响。研究结果表明,β锻造大幅减小了粉末烧结坯的孔隙尺寸,显著提高了合金致密度。锻造后合金的室温拉伸性能优异,拉伸强度达972 MPa,断后伸长率为16 %。合金中的残余孔隙尺寸的减小显著改善了烧结合金的疲劳性能,经固溶时效热处理后,该合金在最大应力480 MPa、应力比0.1的条件下,循环周次可达10?以上。

     

    Abstract: Mechanical properties, especially fatigue properties, of low-cost powder pressureless sintered titanium alloy components are generally inferior to those of forged titanium alloys, while their mechanical properties can be effectively enhanced by subsequent hot working. In this paper, the effects of β forging and solution and aging heat treatment on the microstructure and mechanical properties of TC4 (Ti-6Al-4V) titanium alloy billets prepared by pressureless sintering were studied. It is indicated that β forging significantly reduces the pore size of the as-sintered billet and greatly improves the relative density. The as-forged alloy exhibited excellent room-temperature tensile properties, with tensile strength of 972 MPa and elongation after fracture of 16%. In addition, smaller size of residual pore in the powder TC4 titanium alloy billet after β forging significantly improved the fatigue performance compared to the sintered alloy. After solution and aging heat treatment, the powder alloy achieved more than 10? cycles under the conditions of a maximum stress of 480 MPa and a stress ratio of 0.1.

     

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