离心力及铸件模数对Ti-6Al-4V合金组织与力学性能的影响

Effects of centrifugal forces and casting modulus on structures and mechanical properties of Ti-6Al-4V alloy

摘要:

该论文主要研究在石墨型中不同立式离心力场下离心力及铸件模数对Ti-6Al-4V合金组织及性能的影响。实验过程中铸型的旋转速度主要考虑了三种情况：0, 110及 210 rpm。结果表明：晶粒尺寸及片层厚度随铸件模数的减小和离心力的增加而减小，拉伸强度随铸件模数减小和离心力增加而明显增加，但铸件延伸率呈现相反的变化趋势。文中给出了重力系数、铸件模数与Ti-6Al-4V合金组织和力学性能之间的定量关系。作为与重力场下石墨型中Ti-6Al-4V合金铸件对比分析，研究了金属型中Ti-6Al-4V合金阶梯铸件组织的变化情况，研究发现：两种铸型中浇铸的合金铸件晶粒尺寸、片层厚度随冷却速度的变化趋势基本一致，结合两组实验数据，给出了重力场下Ti-6Al-4V合金铸件组织随冷却速度变化的定量关系。

Abstract:

The present investigation mainly focuses on effects of centrifugal forces and casting modulus on structures and mechanical properties of Ti-6Al-4V alloy formed under different vertical centrifugal casting conditions in graphite molds. Mold rotating rates of 0, 110 and 210 rpm are considered with experimental method. Results show that, grain size and lamellar thickness decrease with the decreasing of modulus or increasing of centrifugal force, and tensile strengths are considerably enhanced with the decreasing of modulus or increasing of centrifugal force, but the elongation shows the opposite changing trend. The quantitative relationships among gravity coefficient, casting modulus and structures or mechanical properties of Ti-6Al-4V alloy have been obtained. As the comparison of Ti-6Al-4V alloy cast in graphite mold under gravity field, the structures of steeped casting in metal mold are also investigated. It was found that the grain size or lamellar thickness in both two molds shows the same changing trend with the cooling rate, and the quantitative relationships between structures and cooling rates have been obtained.