A comparative assessment of the hardness of nano-structured bainitic steel affected by using various quenchants

Quenching, in heat treatment, plays a vital role in controlling material properties. It is the most important step in manipulating the strength of steel. It involves cooling the material from the austenitizing temperature at different cooling rates using variations in quenchants to obtain corresponding material properties. The commonly used quenchants are water, oil, and brine. The cooling rate is the rate at which heat is ejected from the material by the quenchant. The effectiveness of the quenchant is judged by its ability to absorb heat from the material and thermally conduct. Because of stringent regulations regarding use and disposal, there is a need to develop new, environmentally friendly quenchants. The experimental design in this study consisted of quenching austenitized nano-structured bainitic steel in four different quenchants, namely, water, oil, brine, and 1 M sodium carbonate solution. This research gives the insight of substituting conventional quenchants with 1 M sodium carbonate solution. The final four samples were characterized using metallography. A comparative study of the hardness of nano-structured bainitic steel quenched in the newly developed quenchant (i.e., 1 M sodium carbonate solution) and of steel quenched with the conventional one is done. All the results are tabulated, and the applicability of the quenchants is discussed.