Microstructure and Heat Treatment of Hot Work Tool Steel: Influence on Mechanical Properties and Wear Behaviour

E-ISSN： 1662-9795|2018|767|196-203

ISSN： 1013-9826

Source： Key Engineering Materials, Vol.2018, Iss.767, 2018-06, pp. : 196-203

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Abstract

Good mechanical and wear properties of hot-work tool steels are needed for tools to withstand severe service conditions during their operational lifetime. Thus, the aim of this investigation was to correlate mechanical and wear properties with changes in microstructure of commercially available hot work tool steel Sitherm S361R. Hardness, impact toughness, tensile strength and wear tests were performed. Hot-work tool steel was heat treated at austenitizing temperature 1030 °C for 15 min in a horizontal vacuum furnace and gas quenched using nitrogen. One set of samples was investigated in as quenched state. Double tempering of samples was performed after quenching for 2 h at each of chosen temperatures, with first tempering temperature of 500 °C for the whole set of tempered samples. The second tempering was conducted at temperatures from 520 °C to 640 °C with increment of 30 °C for each set of samples. Microstructure of differently heat treated samples showed martensitic matrix, but different fraction and distribution of carbides, consequently influencing hardness, impact toughness, tensile strength, yield strength and wear resistance. Reciprocating sliding wear tests were carried out at room temperature in order to correlate microstructure of differently heat treated hot-work tool steel with wear. In order to achieve adhesive and abrasive wear mechanisms, 100Cr6 and Al₂O₃ balls were used as counter-body, respectively. Combination of adhesive and abrasive wear was observed for all specimens with different hardness when using 100Cr6 material as a counter body. However, in the case of Al₂O₃ abrasive wear was found as the prevailing wear mechanism.