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 M 7 C 3 , the latter being present in all combinations.

Aspectos microestruturais e do comportamento mecânico de revestimento duro depositado pelo processo arame tubular

“…As microestruturas evidenciadas condizem com as reportadas pela literatura, a qual concluiu que as ligas do sistema FeCrC+Nb apresentam basicamente o mesmo tipo de contraste microestrutural das ligas FeCrC, formando-se dendritas de austenita ou carbonetos massivos M 7 C 3 , além da presença adicional de carbonetos NbC na forma primária e/ou em frações mais finas, provenientes de reações mais complexas do sistema quaternário [10][11]. De um modo geral, e de forma similar ao verificado por outros autores [10][11][12][13][14], a microestrutura no centro do cordão observada na Figura 6 de todos os revestimentos da liga FeCrC apresentaram a formação de grandes carbonetos primários do tipo M 7 C 3 com morfologia hexagonal e em forma de agulhas, imersos em uma matriz eutética de austenita mais carbonetos.…”

Influencia de la microestructura en el comportamiento a desgaste abrasivo de depósitos de soldadura antidesgaste aplicados sobre sustratos de acero de baja aleación y bajo carbono

“…Los depósitos realizados con electrodos de alto cromo (West Crome®), mostraron los mejores desempeños cuando se evaluó su comportamiento al desgaste de tipo abrasivo, lo anterior se sustenta en la formación de carburos de tipo M7C3 en matriz martensítica y austenítica, esto como se apreció en el análisis realizado por difracción de rayos X, apoyado con los valores obtenidos de composición química en última capa, además estos recubrimientos presentaron las mayores durezas en relación a los demás recubrimientos aplicados, en las imágenes obtenidas por microscopia SEM no se aprecia deformación plástica, no presentan desprendimiento y sumado al gran tamaño de los carburos respecto a las superficies de corte de la arena, presentan una resistencia al desgaste superior. [15,16].…”

Investigations on quality characteristics in gas tungsten arc welding process using artificial neural network integrated with genetic algorithm

“…However, as Ahn [5] discussed, hardfacing deposited by the welding process can result in considerable heat-affected zones and susceptibility to crack due to residual stresses imposed by the welding. As presented by [6], low-carbon steels are usually used as a substrate, which reduces the costs and supplies considerable amounts of iron during the welding, which can compromise the desired dilution. Therefore, the two main challenges involved in hardfacing deposition are obtaining crack-free overlay and low dilution.…”