Hardenability of PM steel alloyed using tailored master alloys

Abstract

The ferrous powder metallurgy industry is facing major upheavals currently, which, however, also offer opportunities. New materials and concepts, made possible by tailored design, are a way to prepare for new challenges. Alloying of PM steel through the master alloy route is a concept that combines efficient usage of alloying elements, also of such with high oxygen affinity, with accelerated homogenization via liquid phase sintering. Thus, improved properties can be attained while maintaining dimensional precision, which makes the PM route more attractive. In the present study, different master alloys containing Fe, Si, C, Cr and / or Mn have been admixed to plain iron base powder, the mixes then being consolidated by pressing and sintering. The materials thus produced are compared to two commercial sinter hardening PM steel grades in terms of hardenability. CCT diagrams are presented for all materials, and hardness data from quenching dilatometer experiments are compared to the hardness values achieved by sinter hardening in the lab furnace as well as by a classical quench-and-temper treatment. alloying elements, also of such with high oxygen affinity, with accelerated homogenization via liquid phase sintering. Thus, improved properties can be attained while maintaining dimensional precision, which makes the PM route more attractive. In the present study, different master alloys containing Fe, Si, C, Cr and / or Mn have been admixed to plain iron base powder, the mixes then being consolidated by pressing and sintering. The materials thus produced are compared to two commercial sinter hardening PM steel grades in terms of hardenability. CCT diagrams are presented for all materials, and hardness data from quenching dilatometer experiments are compared to the hardness values achieved by sinter hardening in the lab furnace as well as by a classical quench-and-temper treatment.

Die Sinterstahlindustrie ist in letzter Zeit mit einigen Turbulenzen konfrontiert, die jedoch genauso neue Möglichkeiten für Innovationen eröffnen. Neue Materialien und Konzepte, möglich gemacht durch maßgeschneiderte Designs, bieten Chancen, sich auf neue Herausforderungen vorzubereiten. Damit lassen sich verbesserte Eigenschaften realisieren, wobei die für die Pulverroute so wichtige Dimensionsstabilität gewährleistet bleibt. In dieser Arbeit wurden Masteralloys, die Fe, Si, C, Cr und / oder Mn enthalten, mit Reineisenbasispulver vermischt, über die klassische Press- und Sinter-Route verarbeitet. Ihre Härtbarkeit wurde mit der von zwei kommerziellen Sinterstählen verglichen. Kontinuierliche ZTU-Diagramme wurden erstellt und gasabgeschreckte Materialien aus dem Abschreckdilatometer wurden mit Härtedaten von Materialien verglichen, die im Laborofen gasabgeschreckt und getempert sowie ölabgeschreckt und angelassen wurden.