Process for extruding maraging steel

摘要

This invention provides a method for cold extruding 18% nickel maraging steel to form an article of manufacture, such as a sub projectile blank for the manufacture of cannon rounds which includes performing a series of cold extrusion operations on an extrusion blank with a tapered punch to produce a combination forward extrusion and backward extrusion. On the first cold extrusion operation a tapered hole is formed in the extrusion blank and the extrusion blank is elongated. Subsequent cold extrusion operations progressively elongate both the extrusion blank and the tapered hole. The punch and die geometry are such that the tapered hole is elongated by penetration of the punch into the blank and additionally backward extrusion of the material around the punch. Additionally, as the tapered hole becomes increasingly longer, a floating punch is employed wherein at least a portion of the punch is supported by the walls of the tapered hole.