PURPOSE: To improve the service-life by forming a die main body by the steel of tough hardening, forming an opening part by the graphite crystalized Ni/Cr cast iron of specified composition, integrating both by combing with diffused joining and serving tough hardening, wear resistance and seizure resistance as well.
CONSTITUTION: The die main body 2 of a composite die 1 for extrusion is formed by the steel having the tough hardening property of high fatigue strength. The opening part 3 opening an extrusion hole 4 is formed by the graphite crystalized Ni/Cr cast iron of the composition made by 1.0W1.9wt.% C, 4.0W1.5% Ni, 1.5W4.0% Si, 2.0W4.5% Cr, 0.5W1.5% Mn, 0.4W1.0% Mo, ≤0.1% P, ≤0.008% S and the balance Fe actually. These die main body 2 and opening part 3 are integrated with their diffused joining by hot hydrostatic pressurizing, etc. The composite die for extrusion serving for tough hardening property, wear resistance and seizure resistance as well can be thus offered.
MORIKAWA TAKERU
NAKAGAWA YOSHIHIRO
