Powder metallurgical high-speed steels

Background/aims: The ASP-steels have been produced in Soderfors since the early 1970s. Their excellent mechanical properties are best suited for production of highly stressed tools of large size. The high strength will reduce the tendency of fracture or wear caused by chipping of tools produced from these materials. The toughness of PM high-speed steel depends on the number and size of non-metallic inclusions in the material. Methods: The ASP-process, comprising hot-isostatic pressing (HIP) of rapidly solidified gas atomized powder, produces a material of homogeneous distribution of the components of the steel and of low content of inclusions. An ESH-tundish process has recently been developed which reduces the amount of inclusions to an even lower level. Results: The ESH (electro-slag heating)-process has increased the strength of the new ASP 2000-materials by about 20% compared with the previous generation of PM-steels. Improved cutting tool performance with significantly less statistical spread of results and for plastic mould tools up to 5x lower rejection ratio. 2 new steel grades, ASP 2017 and ASP 2053, have been developed and produced with application-adapted properties. Conclusions: The ESH-process will produce powder metallurgy high-speed steels, ASP 2000-alloys, of very low content of nonmetallic inclusions for high mechanical strength and superior tool performance. (C) Munksgaard, 1996