Numerical Simulation and Experimental Research of the Hydrostatic Extrusion Process of Pure Tungsten

Abstract

A finite element model (FEM) of the hydrostatic extrusion (HE) process with pressure load model is established in this paper. On this basis, the hot hydrostatic extrusion process of sintered pure tungsten under different temperatures (T), extrusion ratios (R) and die angles (α) are simulated by introducing the Johnson-Cook constitutive relation for material flowing behavior. The simulation results show that there is a negative correlation between the extrusion pressure (P) and T, a positive correlation between P and lnR. And during the increase of the α value, the P value decreases first and then increases. The die angle corresponding to the minimum P is different under different extrusion ratio. Furthermore, a tendency of internal cracking during the process can be found when the R value is relatively small. Based on the simulation results, the experiment of hot hydrostatic extrusion of sintered pure tungsten is carried out. The microhardness, microstructure and mechanical properties of the tungsten before and after the process are investigated. The results show that after the hot hydrostatic extrusion, the grain size of the tungsten is subdivided, the hardness is improved obviously and the mechanical properties is remarkable.