The Effect of New Double Solution Heat Treatment on the High Manganese Hadfield Steel Properties

In this paper, the influence of double solution process on microstructure changes and the hardness behavior of Hadfield steel at different quenching environments were investigated. High magnesium (17.5 wt.%) Hadfield steel with different mean grain sizes, alloy carbides, and sulfides inclusions was prepared during different heat treatments. Scanning electron microscopy, optical microscopy, X-ray diffraction, energy-dispersive spectrometry, and Rockwell B hardness test (HRB) were used to study the microstructural features and properties of various samples. Results show that the double solution heat treatments were more effective than the standard solution process to dissolve more amount of carbides in the austenite phase. The specimen, which had the mean grain size of 145 μm through the double solution process at 1100 °C, contained lower amount of sulfides inclusions and showed lowest hardness (92.1 HRB). However, the salt solution quenching environment had a fast quenching rate to dissolve more amount of carbides, and this environment caused microscopic cracks on the specimen surface. This environment could be substituted by the mixture of water and ice with the temperature of 0 °C in the second stage of solution heat treatment. In this situation, the mean grain size decreased to 115 μm to show the higher hardness value of 95.4 HRB, although a small amount of (Fe, Mn)₃C phase was distributed in the austenite matrix.