Microstructure and Abrasion Resistance of Fe-Cr-C and Fe-Cr-C-Nb Hardfacing Alloys Deposited by S-FCAW and Cold Solid Wires

Abstract

This work assesses the wear resistance behavior of different high Cr and Nb alloyed hardfacing deposits carried out by Self-shielded Flux Cored Arc Welding, considering the resulting microstructures as base for the analysis. To obtain non-commercial alloys, an “in-situ” technique was employed with addition of cold wire into the weld pool. Six combinations of two commercial FeCrC and FeCrNbC tubular wires and three different solid wires (AWS ER 70S-6, ER308LSi and ER 430) were used to obtain white cast iron hardfacing deposits on plain carbon steel subtracts. The welding parameters were identical for all combinations. Each deposit was characterized taking into account the resulting microstructure, hardness and abrasion wear resistance. The addition of a ferritic stainless solid wire in the weld pool resulted in the best wear resistance, which was boosted if Nb is present in the S-FCAW wire. The reason for these results was microstructure refinement and the presence of NbC and M₇C₃, the latter being present in all combinations.

Key-words:
Hardfacing; Cr and Nb cast irons; Self-shielded flux cored arc welding; Cold wire; Abrasion wear