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采用超塑成形/扩散连接(SPF/DB)工艺对TC4钛合金二层板结构进行制备。对TC4钛合金试样进行超塑拉伸试验研究,确定了温度900℃和应变速率9.8×10-4s-1为最佳超塑成形的工艺参数,并计算得出本构方程中的应变速率敏感指数m=0.57,K=998.5。利用MSC.MARC软件对试验件的成形过程进行有限元模拟分析,获得了优化的压力-时间加载曲线。模拟结果显示板料在拐点圆角处最薄,且最大减薄率为42.5%,最大成形气压为2.0MPa;在T=900℃和??=9.8×10-4s-1下,加载优化的压力-时间曲线,成功进行了TC4二层板结构SPF/DB成形试验。最后对试验件进行了表面质量检查和扩散连接位置显微组织观察分析,结果显示:钛合金二层板的试验件的整体成形效果良好,试验件表面没有出现凹坑缺陷的现象,加强筋超塑成形完全;扩散连接情况良好,界面无明显缺陷,连接处实现了可靠的冶金连接。证明了所述工艺方案成形二层板结构件的可行性。
TC4 titanium alloy two-layer plate structure was prepared by superplastic forming / diffusion bonding (SPF / DB) process. The superplastic tensile test of TC4 titanium alloy was carried out. The optimum technological parameters of superplastic forming at temperature 900 ℃ and strain rate 9.8 × 10-4s-1 were determined. The strain rate in the constitutive equation Sensitive index m = 0.57, K = 998.5. The forming process of the test piece was analyzed by finite element method with MSC.MARC software, and the optimized pressure-time loading curve was obtained. The simulation results show that the sheet material has the thinnest corner at the inflection point with the maximum thinning rate of 42.5% and the maximum forming pressure of 2.0 MPa. At T = 900 ℃ and 9.8 × 10 -4 s -1, Pressure-time curve, successful TC4 two-layer structure SPF / DB forming test. Finally, the surface quality of the test piece was examined and the microstructure of the diffusion bonding site was observed and analyzed. The results showed that the overall forming effect of the test piece of the titanium alloy two-layer plate was good and the surface defect of the test piece did not appear. The plastic is fully formed; the diffusion connection is good, the interface has no obvious defects, and the junction has a reliable metallurgical connection. The feasibility of the process scheme for forming two-layer plate structures is demonstrated.