热处理对Ti-6Al-7Nb钛合金组织及性能的影响
Effect of Heat Treatment on Microstructure and Mechanical Properties of Ti-6Al-7Nb Titanium Alloy
唐晓东, 杜予晅, 刘向宏
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作者单位：西部超导材料科技有限公司, 陕西 西安 710018
中文关键字：热处理； 医用钛合金； Ti-6Al-7Nb
英文关键字：heat treatment; medical titanium alloy; Ti-6Al-7Nb
中文摘要：制备了细等轴、粗等轴、网篮三种不同初始组织的Ti-6Al-7Nb棒坯，研究了固溶温度、时效温度和时间对Ti-6Al-7Nb钛合金的性能及显微组织的影响。结果表明，试样强度随固溶温度的升高而升高，但超过相变点后，强度有所下降，而塑性则随固溶温度升高明显降低。随时效温度升高，等轴α相尺寸大大增大，含量基本无变化，在550 ℃时效的样品获得了最大的强化效果。在相同的时效温度(600 ℃)下，延长时效时间抗拉强度明显提高，但屈服强度基本保持稳定，塑性有恶化趋势。通过热处理形成的等轴α相有利于提高塑性指标，形成的次生条状α相有利于提高强度指标。在本研究中，具有等轴初始组织的棒坯最佳热处理制度为：940 ℃ × 1 h，AC + 550 ℃ × 4 h，AC；网篮初始组织的试样还需要通过其他方法进一步提高塑性。
英文摘要：Ti-6Al-7Nb bars with three type initial microstructures(including fine equiaxed, ordinary equiaxed and basket-weave) were prepared. And the effects of solution temperature, aging temperature and aging time on mechanical properties and microstructure of Ti-6Al-7Nb alloy were investigated. The results show that the strength increases with the increase of solution temperature, while plasticity decreases. However, strength drops sharply. With the increase of aging temperature, the size of equiaxed alpha phase increases obviously, but volume fraction is keeping stable. The peak strength is obtained at 550 ℃. During aging process at 600 ℃, ultimate tensile strength increases with aging time increasing, and yield tensile strength keeps stable, and plasticity drops. The results also show that equiaxed alpha phase increases plasticity while lamellar alpha phase is good to strength. The best heat treatment process is: solution at 940 ℃ for 1 h, AC and aging at 550 ℃ for 4 h，AC. The plasticity of basket-weave initial structure should be improved by some methods for industrial application.