Corrosion-resistant analogue of Hadfield steel

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 420; no. 1-2; pp. 47 - 54
• Main Authors: Gavriljuk, V.G., Tyshchenko, A.I., Razumov, O.N., Petrov, Yu.N., Shanina, B.D., Berns, H.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 25-03-2006; Elsevier
• Subjects: Applied sciences; Austenitic steel; Carbon + Nitrogen; Corrosion; Corrosion prevention; Electron structure; Exact sciences and technology; Metals. Metallurgy; Phase equilibrium; Strength; Wear; Electron structure; Corrosion; Carbon+Nitrogen; Austenitic steel; Wear; Phase equilibrium; Strength; Charge carrier density; Mechanical properties; Nitrogen addition; Pinhole; Carbon + Nitrogen; Corrosion resistance; Potentiodynamic method; Electronic structure; Carbon addition; Corrosion test; Free electron; Ab initio calculations; Microstructure
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2006.01.066

The concept of alloying austenitic steels with carbon+nitrogen is used for the development of a corrosion-resistant austenitic CrMn steel having an impact wear resistance close to that of the Hadfield steel. A higher stabilization of the austenitic phase by C+N, as compared to carbon or nitrogen alone, is substantiated by ab initio calculation of the electron structure, measurements of the concentration of free electrons and calculations of the phase equilibrium. Based on these results, the compositions (mass%) Cr18Mn18C0.34N0.61 and Cr18Mn18C0.49N0.58 were melted and tested along with Hadfield steel Mn12C1.2. Mechanical tests have shown that, as compared to the Hadfield steel, the experimental steels possess a higher strength, plasticity, hardness and the same resistance to impact wear. TEM studies of the surface layer after impact treatment revealed a mixture of the amorphous phase, nanocrystals and fine-twinned austenite. At the same time, using Mössbauer spectroscopy of conversion electrons, the ferromagnetic ordering was found in the surface layer of up to 10μm in depth, which is the sign of the strain-induced martensitic phase. The hypothesis of a transition from the low-spin to the high-spin state of the iron atoms within the thin twins in austenite was proposed in order to interpret the discrepancy between TEM and Mössbauer studies. Potentiodynamic measurements and immersion tests show that the CrMnCN steels possess a significantly higher pitting potential and resistance to general corrosion in comparison with Hadfield steel.