Abstract

Manufacturing of steel components is often done at high temperatures (HT) posing a serious challenge to components such as forming tools. Thermal spray coatings provide a costeffective solution for surface protection under HT; corrosive environments and severe wear conditions. Thermally sprayed coatings based on cubic hard materials such as TiC and TiCN can provide an alternative to widely used Cr3C2-NiCr. While the latter possess a superb oxidation resistance and wear resistance at HT; they are prone to degradation in the presence of Mn; an element commonly alloyed in many modern steel grades such as TWIP (twinning-induced plasticity steel). In this study; a (Ti;Mo)(C;N)-29% Ni hardmetal feedstock powder was prepared by agglomeration and sintering. Coatings were deposited using a high velocity air-fuel (HVAF) spray process. The coating was benchmarked against a standard Cr3C2-NiCr coating obtained with the same spray process. Our work comprises analyses of the feedstock powder along with the resulting coating microstructure after deposition and heat treatment. Further; the HT sliding behavior against TWIP steel using a HT pin-on-disc tribometer at 700°C was investigated. The results showed a clear benefit of the TiCN-based coating; with almost no wear detected; while the Cr3C2-coating showed a significant wear loss. Based on these results; the TiCN-based coating is regarded as potential solution for prospective forming applications of modern high Mn steels; such as TWIP.

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