固溶工艺对Ti12LC合金组织性能的影响

Ti12LC合金是西北有色金属研究院研制的一种低成本钛合金,用于取代TC11合金进行推广应用。本文对420mm Ti12LC合金铸锭进行常规锻造,得到等轴组织的170mm Ti12LC合金棒材。采用单重固溶＋时效、双重固溶＋时效两种不同的工艺对Ti12LC合金进行热处理,分析不同固溶工艺对Ti12LC合金显微组织及室温拉伸、室温冲击性能的影响。研究表明,在相同的固溶冷却速率下,增加单重固溶温度,初生等轴α相含量减少,合金强度增加、塑性减小、冲击韧性减小。单重固溶＋时效热处理后合金冲击韧性低、强韧性匹配差。与单重低温固溶＋时效相比,合金经高温预固溶慢冷＋低温固溶处理后,初生α相尺寸及相含量变化不明显,但可以获得更大尺寸的次生α相,合金的塑性稍有降低、强度增加、冲击韧性改善明显,综合力学性能匹配良好。

Effect of Solution Treatment on Microstructure and Properties of Ti12LC Alloy

The low cost Ti12LC titanium alloy was developed by Northwest Institute for Non-ferrous Metal Research to replace TC11 titanium alloy. The Ti12LC cast ingot of Ф420 mm was forged by conventional process, and worked in Ф170mm equiaxed bars finally. The equiaxed Til2LC alloys were single and duplex solution treated separately, and then aged at 540 ℃ for 6 h. The effects of different solution processes on the morphology and mechanical properties, especially the impact toughness were analyzed. The results show that the content of primary equiaxed a phase, the plasticity and the impact toughness decrease, but the strength of the alloy increases, when the solution temperature of α ＋β phase field single solution ＋ aging heat treatments increases, for which the solution cooling rate is constant. The single solution ＋ aging heat treated alloys have low impact toughness, which means that the impact toughness and strength are mismatched. Com- pared with single solution at low temperature, pre-solution at the upper α ＋β phase field followed by furnace cooling, and then re-solution at low temperature can result in larger dimension secondary α phase, higher strength and impact toughness, while the plasticity decreases in acceptable range, the content and dimension of primary α phase change little. The combined mechanical properties of the Ti12LC alloys heat treated by duplex solution ＋ ageing match well.