ABSTRACT
High nickel steels offer the opportunity to produce powder metallurgy components with excellent high strength and ductility combinations. These alloys are a sinter-hardenable class of materials that do not require conventional heat treatment processes to develop these unique properties. The alloys must be sintered at high temperatures in order to obtain the value of the elemental additives that are included in these ferrous alloys – as well as the enhancement of the densification process. As-sintered properties include UTS values near 1380 MPa (200 ksi), yield strengths over 827 MPa (120 ksi) and elongations over 2%. In addition, impact energy values are over 40 J (30 ft. lbf.). A post-sinter temper/draw cycle did not further improve mechanical properties of the PM steels with higher Ni contents, and was deemed unnecessary. When component failure due to insufficient ductility is not an option, these materials can readily justify the slightly higher cost.
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