Laser composite surfacing of A681 steel with WC+Cr+Co for improved wear resistance

摘要

Laser surface alloying (LSA) is a surface treatment technique. It involves the near surface melting by a powerful laser beam with a pre-deposited or concomitantly added alloying element along with a part of the underlying substrate to form a surface alloyed zone. In this paper, it is reported the treatment by laser surface alloying of a cold work steel ASTM A681 substrate simultaneously fed with a powder mixture of 86wt.% WC+8wt.% Cr+6wt.% Co. It was carried out using a continuous wave λ =1064nm fiber-coupled diode laser with five different laser intensities – resulting in five specimens – and then studied and analyzed their microstructure, phases, composition and microhardness. One of these configurations was applied to enhance a deep drawing tool for automotive steel sheet stamping. The process modified the specimens near surface layer, from a ferritic structure into an austenitic matrix with a refined dendritic microstructure, with an enhanced surface hardness from 250 HV to ～560 HV. The treated deep drawing tool showed remarkable wear improvement compared to a non-treated one after one thousand stamps. This result allows the process for industrial applications.