Investigation on the Effects of Using Salt Water Bathroom Quenching on the Corrosion Behavior of Hadfield Manganese Steel

In this study, effects of using quenching in aqueous salt solution, on the corrosion behavior of Hadfield Manganese Steel was investigated. For making manganese steel according to ASTM A-128C standard, initially two Y-shaped aluminum models prepared and then castings made through Sodium Silicate/CO2 procedure by closed feeding method. Melting was conducted in non-core induction furnace. After the casting, both samples austenitized in 1100°C for 2 hours and then one block quenched in pure water and the other quenched in the aqueous 3.5% salt solution. To evaluate the corrosion behavior of samples, potentiodynamic polarization and electrochemical impedance spectroscopy methods in the 3.5% NaCl solution were used. The results of both methods indicates corrosion resistance of salt bath quenched sample is significantly higher than the other. This is due to:
a)-salt solution quenching medium decreased the amount of carbides in the microstructure and prevented the formation of galvanic cell.
b)- Quenching in salt solution increased the solubility of carbon in the austenite phase that caused the reducing the amount of grain boundaries.