TC4钛合金负角度零件超塑成形及性能研究

Superplastic Forming and Mechanical Properties for TC4 Alloy Negative-Angle Part

在前期材料实验的基础上对TC4钛合金负角度零件超塑成形过程进行仿真,获得压力-时间曲线和壁厚分布,并根据仿真结果中接触摩擦力分布情况,预测了模具磨损。对仿真获得的压力-时间曲线进行修正,并将修正后曲线作为实际加载曲线进行超塑成形实验,获得负角度零件。比较了零件型腔底端壁厚的实际结果与仿真结果,同时,研究了成形零件的负角度壁壁厚分布、显微组织、力学性能。结果表明:取件温度为300℃时,零件外形及表面质量较好;实际零件型腔底端壁厚分布与仿真结果趋势相同,两者最大误差为4.4%;零件最小壁厚在负角度过渡圆角处,其值为0.66 mm,最大减薄率为67%;负角度壁壁厚标准差为0.186 mm,说明此部位壁厚分布比较均匀;成形后材料的晶粒尺寸长大明显,而室温屈服强度、抗拉强度、延伸率从原始材料的951,1045 MPa,13.9%下降至853,955 MPa,10.8%,说明经过超塑成形后,材料由于晶粒长大而导致力学性能下降。

The superplastic forming progress of the TCA alloy negative-angle part was simulated on the basis of previous material ex- periment. The p-t curve and thickness distribution were acquired, and the wear of the die was predicted according to contact friction force distribution in simulation results. The p-t curve acquired from simulation was revised, and the superplastic forming experiment was done using the revised p-t curve which was acted as an actual load curve. Then, the negative-angle part was obtained. The bottom thickness of the part cavity was compared between actual result and simulation result. Meanwhile, negative-angle wall thickness, mi- crostructure and mechanical properties of the part were studied. The results showed that the appearance and surface quality was good while the part was taken out at the temperature of 300 ~C. The trend of thickness distribution of the part cavity was similar between the actual result and the simulation result, and the maximum error was 4.4% of them. The minimum thickness was 0.66 mm which was in the position of negative-angle fillet, and the biggest thinning rate was 67%. The negative-angle＇s wall thickness standard deviation was 0. 186 mm, indicating that the thickness distribution of this location was even. After SPF, grain size of the material obviously grew up, and the room temperature yield strength, tensile strength and elongation decreased to 853,955 MPa, 10.8% while the raw material of them were 951. 1045 MPa. 13.9%. it showed that the mowth of main size would result in mechanical orooerties decline after SPF.