Surface electron beam melting and alloying of tool steels

Abstract

Surface melting and alloying of D3 steel using an electron beam has been carried out to improve its surface microstructure and properties. The solution of primary carbides, together with rapid solidification and subsequent cooling, enhance the solubility of alloying elements in the γ Fe phase and thus influence the behaviour of the steel on subsequent tempering. The surface melted zone consists of dendrites without primary carbides, which is also the case for samples alloyed with WC, SiC, or Al₂O₃. When alloyed with TiC or TiB₂, the materials contain TiC or TiB₂ primary phase respectively in addition to the iron rich dendrites. Some unmelted TiB₂ particles are also present. On tempering, both electron beam melting and alloying change the secondary hardening characteristics, increasing the peak hardness and the peak hardness temperature.

MST/1194