钛合金实心锭穿孔挤压穿孔过程有限元分析

Finite Element Analysis of Piercing Process of Piercing Extrusion for Titanium Alloy Solid Ingots

探明实心锭穿孔过程的材料流动和穿透断裂行为对高性能优质无缝管材的实心锭穿孔挤压推广应用具有重要意义。以直径200 mm实心锭为原料,穿孔挤压成直径80 mm、壁厚10 mm的钛合金管材为研究对象,基于DEFORM-2D软件环境,建立了能够描述材料流动和穿透断裂行为的实心锭穿孔挤压穿孔过程的热力耦合有限元模型。研究分析了2种形状穿孔冲头的穿孔过程。结果表明:穿孔初始阶段变形行为类似正挤压,随后材料反向流动,堵头去掉前都是反挤压变形;正挤压变形下穿孔力迅速上升,上升至稳定值后开始反挤变形,去掉堵头后的穿透断裂阶段穿孔力迅速下降;采用圆柱形穿孔冲头情况下反挤时穿孔力变化幅度不大,而采用瓶形穿孔冲头情况下的穿孔力稳定一段时间后再次显著增加,瓶形穿孔冲头的穿孔力远大于圆柱形穿孔冲头的穿孔力;穿透断裂阶段,圆柱形穿孔冲头下的断裂行为类似于冲裁断裂,而瓶形穿孔冲头下的约束增强,其断裂面近似呈L型。

Metal flow and penetration fracture behavior is important for application of piercing extrusion process of solid ingots for high-performance seamless tube. A piercing extrusion process from a solid ingot（Φ200 mm） to a titanium alloy tube（Φ80 mm×10 mm） has been studied. Based on FE software of DEFORM-2D, a thermo-mechanical coupling model being able to describe the metal flow and penetration fracture behavior was developed for the piercing process of piercing extrusion of solid ingots. The piercing processes by two kinds of piercing punches were analyzed. The results indicate that at the initial stage of piercing process, the deformation characteristic is similar to forward extrusion, and then metal reverse flows, and the backward extrusion remains until the end cap is removed; the piercing force increases rapidly under forward extrusion, and backward extrusion occurs when the force rises to the stable value, and the piercing force decreases rapidly at the penetration fracture stage after removing the end cap; under backward extrusion, the piercing force has a little change by a cylindrical piercing punch, but the force will significantly increase again after a short stable stage by a bottle piercing punch, and thus the piercing force by the bottle piercing punch is much greater than that by the cylindrical piercing punch; at the penetration fracture stage, fracture behavior by the cylindrical piercing punch is similar to that in blanking process, but the fracture face by the bottle piercing punch presents an approximate L-shape.