High toughness high hardness iron based PTAW weld materials

Abstract

New iron based alloys were developed for industrial hardfacing via plasma transferred arc-welding (PTAW). The alloys were designed with low critical cooling rates for metallic glass formation so that high undercooling could be obtained prior to the initiation of nucleation. The result was that conventional dendritic solidification could be avoided resulting in the refinement of metallurgical grain/phase sizes through a coupled lath eutectoid growth mode. High hardness up to R c 66 was developed from the fine structure consisting of a high volume fraction of borocarbides phases. Using a Palmqvist method, high toughness up to 74.7 MPa m 1/2 was measured which could adequately be described through a crack bridging model. The effective distribution of borocarbides phases with ductile iron in a coupled lath morphology appears to be especially potent for crack bridging and is believed enabling to achieve combinations of high toughness along with high hardness. Thus, this new class of PTAW hardfacing alloys is expected to be useful for applications requiring high abrasion resistance and high impact.