Micro-abrasive Wear Behavior of Nitrided and Multilayer Coated High Vanadium Powder Metallurgy Alloy
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TO fulfill the increasing requirements for the production of metal parts in industry, such as the increasing demands, quality of the manufactured products, increase in lifetime and others, cold work tool steel properties need to be enhanced. Vanadis 10 is a hot isostatic pressing (HIP) high vanadium powder metallurgy alloy with high carbon content that combines high abrasive wear resistance, good toughness and good chipping resistance. The powder metallurgy process enables obtaining a refined microstructure, homogeneous carbide distribution in the matrix, and no segregation or inclusions. The high temperatures and pressures applied in the hot isostatic pressing process also reduce the porosities that are common in the conventional route of powder metallurgy.[1,2]
E.A. DOS S. DE ALMEIDA, B.F. ZAPPELINO, R.K. SALVADOR, F. CORREA, B. NUNES, C.E. DA COSTA, and J.C.G. MILAN are with the Universidade do Estado de Santa Catarina (UDESC), Joinville, Santa Catarina, Brazil. Contact e-mail: [email protected] A.P. KRELLING is with the Instituto Federal de Santa Catarina (IFSC), Joinville, Santa Catarina, Brazil. Manuscript submitted August 27, 2019.
METALLURGICAL AND MATERIALS TRANSACTIONS A
The high vanadium content inhibits grain growth during heat treatment and promotes the formation of hard vanadium carbides, which increase the hardness and wear resistance of the alloys.[3] On the other hand, the high carbon content of this alloy leads to the final martensite transformation (Mf) at a temperature below 0 C, which means that some retained austenite will remain in the final microstructure. The presence of the retained austenite reducing the hardness, wear resistance and transformation during life causes volume changes. Deep cryogenic treatment (DCT) is an alternative to promote this transformation. Martensitic microstructure is more refined and transformation is more complete with the application of the DCT in contrast to conventional quenching.[4–7] The combination of a diffusion treatment (nitriding) with film deposition can provide highly demanding properties for the tool steels that could not be achieved by a single surface treatment. This combination provides higher wear resistance allied to an increased load-bearing capacity.[8] Duplex treatment of tool steels and different Vanadis grades are reported in the literature. The adhesion of Cr2N film was enhanced by prior plasma nitriding treatment of Vanadis 6, but the compound layer formation (Fe3N or Fe4N) consequently impaired the adhesion and wear resistance.[9]
Micro-scale abrasive wear tests are largely applied to access the micro-abrasive wear behavior and resistance of the bulk or coated materials, where the substrate and coating wear coefficients are determined simultaneously.[10–18] Particle dynamics has a great influence on wear as discussed in References 17 and 18. Particles can roll freely, producing indentations in the wear crater, namely rolling micro-abrasive wear, or becoming embedded and producing grooves in the wear crater, namely grooving micro
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