不同铸型对钛合金微观组织及力学性能的影响

Effect of Different Molds on Microstructure and Mechanical Properties of Titanium Alloys

为了研究陶瓷和石墨铸型对ZTC4钛合金微观组织机理的影响,采用数值模拟与实验分析相结合的方法,研究了2种铸型的试样在凝固传热过程中的冷却速度、凝固速度、凝固时间对微观组织和力学性能影响。结果表明:与陶瓷型试样相比,石墨型的散热效果好、冷却速度快、凝固速度高,且石墨型的冷却速度提高了52.04%,使得微观组织为急冷生成的细小板条马氏体α,晶粒较小、取向较多、凝固厚度大,导致力学性能中的屈服强度、抗拉强度、硬度分别提高了6.7%、2.6%和4.2%,但伸长率和断面收缩率分别降低了11.62%和34.5%。同时同种铸型的不同位置对冷却速度快慢的影响依次为:中间>底部>顶部。

The effects of different casting molds on the microstructures and mechanical properties of ZTC4 titanium alloy were studied.The effects of cooling rate,solidification rate and solidification time on the microstructures and mechanical properties of ZTC4 titanium alloy were studied by numerical simulation and experimental analysis.The results show that compared with the ceramic sample,the graphite sample has better heat dissipation effect,faster cooling speed and higher solidification speed,which makes the microstructure of the sample be fine lath martensiteαproduced by quenching,with smaller grain size,more orientation and larger solidification thickness.The yield strength,tensile strength and hardness of the mechanical properties are increased by 6.7%,2.6%and 4.2%,respectively,but the elongation and section shrinkage are decreased by 11.62%and 34.5%,respectively.Besides,different positions of the same mold have some influence on the cooling rate.The cooling rate at different positions of the sample is in the order of middle>bottom>top.