Effect of Heat Treatment Conditions on Retained Austenite and Corrosion Resistance of the X190CrVMo20-4-1 Stainless Stee
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Effect of Heat Treatment Conditions on Retained Austenite and Corrosion Resistance of the X190CrVMo20‑4‑1 Stainless Steel M. C. Bignozzi1 · L. Calcinelli1 · M. Carati2 · L. Ceschini1 · C. Chiavari3 · G. Masi1 · A. Morri4 Received: 26 March 2019 / Accepted: 15 July 2019 © The Korean Institute of Metals and Materials 2019
Abstract In the present work the microstructural characterization of the powder-metallurgy X190CrVMo20-4-1 has been performed and correlated with its corrosion properties. The martensitic stainless steel was hardened at different austenitizing and tempering temperatures. Microstructural analyses were carried out using Scanning Electron Microscopy (SEM–EDS) to define the carbide distribution in the steel matrix. Carbides morphology and retained austenite content were evaluated and correlated to the corrosion behaviour of the different heat-treated steels, investigated by means of electrochemical tests. The 7C3 Cr-V based carbides homogenously dispersed in the matrix in annealed and results show the presence of M23C6 and M quenching-and-tempering conditions. The carbides dissolution was evaluated by image analysis in every different heat treatment condition. When low tempering temperature was applied, an increasing in retained austenite content was defined by high austenitizing temperature and elevated carbides solubilization. At high tempering temperature, retained austenite content was not up to 5% nor affected by austenitizing temperature. Contrary to the expectations, HRC hardness was not influenced by the heat treatment conditions and retained austenite content. Corrosion resistance of the different heat-treated samples was found to be mainly influenced by retained austenite volume fraction and the tempering temperature. In particular, high austenitizing temperature and low tempering temperatures allowed the best corrosion resistance among the different heat treatment parameters investigated. The results obtained in the experimentation can provide support to the heat treatment optimization of the steel, widely used in tool and mould applications. Keywords Tool steel · Quenching and tempering · Carbides · Retained austenite · Corrosion · Current density-potential curve
1 Introduction Martensitic stainless steels are high-carbon and high-chromium ferrous alloys widely used in many industrial applications because of their high strength, high hardness and wear resistance, combined with a good corrosion resistance. * A. Morri [email protected] 1
Department of Civil, Chemical, Environmental and Materials Engineering (DICAM), University of Bologna, via Terracini 28, 40136 Bologna, Italy
2
Closures, Containers & PET Division, SACMI IMOLA S.C., Via Selice Provinciale, 17/A, 40026 Imola, BO, Italy
3
Department of Cultural Heritage (D.B.C.), University of Bologna, via degli Ariani 1, 48121 Ravenna, Italy
4
Department of Industrial Engineering (DIN), University of Bologna, viale del Risorgimento 4, 40136 Bologna, Italy
These properties, however, are significantly
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