Comparison of Plasma Transferred Arc and Submerged Arc Welded Abrasive Wear Resistant Composite Hardfacings
EComposite hardfacings produced by Plasma Transferred Arc Welding (PTAW) and Submerged Arc Welding (SAW) possess a good combination of hardness, wear resistance and fracture toughness, thus providing high wear resistance. Although they cannot substitute and be compared with conventional WC-Co based hardmetals, still they can be used in many applications where high wear resistance, hardness and toughness are in great demand. In this study two different hardfacing production technologies PTAW and SAW, were used to produce the hardfacings for abrasive wear conditions. In both cases hardfacings were welded on the top of low alloy steel using different proportions of disintegrator milled hardmetal WC-Co powder of different fractions as a reinforcement and self-fluxing alloy as a matrix. They were analysed in regard to Rockwell and Vickers hardness, wear behaviour, and microstructural analysis. SAW hardfacings were subjected to Rockwell hardness test after process and after two cycles of tempering; secondary hardness effect was detected as increment of hardness values from 39 HRC to 58 HRC after first cycle of tempering. High Vickers hardness values did not correlate with wear results, as it commonly shows hardness of hardmetal particles. Dissolution of hardmetal particles in the matrix was observed in both PTAW and SAW hardfacings with higher amount in the later. This amount correlated with heat input during welding process. Wear test results in abrasive emery wear (AEMW) and abrasive wheel wear test (AWW) showed almost analogous tendency, with slightly lower wear in later. Both types of hardfacings have shown promising results in intensive wear conditions.
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