Residual stresses in hydrostatically extruded copper rod

Residual tensile stresses in the longitudinal and tangential directions existed at the surface of rods extruded at ratios from 1. 2 to 2. 4, and having included die angles ranging from 20 to 90//0. Longitudinal tensile residual stress decreased with increasing extrusion ratio. High- speed extrusion (20 m/sec) caused higher residual tensile stress than low- speed extrusion.