Comparison of a Medium Carbon Steel Microscopic and Hardness Properties Following Different Heat-Treatments

Abstract

This article investigates how medium carbon steel's microstructure and hardening strength are affected by repeated heat treatment. Finding out the impact of repeatedly heat-treating medium carbon steel is the primary goal of this investigation. In this study, four different heat treatment techniques were used: first quenching, first tempering, second quenching, and second tempering. During the first quenching process, the samples were heated at 870℃ and left in the oven for 45 minutes. The samples were then quenched in distilled water at different temperatures (0, 5, 10, 15, 20℃). The first tempering step, which lasted 25 minutes at 350℃, came after the first quenching step. The samples were heated to 850℃ and placed in the oven for 45 minutes in order to undergo the second quenching process. After that, the samples were quenched at various temperatures (0, 10, 20, and 30℃) in a medium containing distilled water. The second tempering procedure came after the second quenching step, which lasted 25 minutes at 450℃. All samples underwent microscopic inspections and hardness tests following the various heat treatment processes. Each sample's five surface areas underwent hardness testing and microscopy, and the results were compared and analyzed. Research has shown that the steel has undergone various heat treatment procedures, resulting in varying microstructure and hardness values. The hardness of the models that underwent repeated hardening procedures has been shown to significantly increase. In addition, the specimens obtained after the first and second quenching and tempering exhibit a good combination of mechanical properties due to their microstructure. This is because the specimens become more ductile and tough as a result of the quenching and tempering processes, which decrease fragility.