Enhancing Mechanical Properties of Low Alloy Steel through Novel Molten Bi-Ga Austempering

Abstract

The main goal of this study is to improve the mechanical properties of low-alloy steels using an austempering heat treatment that involves combined molten bismuth and gallium (Bi-Ga) alloys. The cooling media is an alternative to the salt media, which is commonly used for austampering heat treatment. The steel was maintained at a constant temperature of 500 °C by immersing it in a cooling medium containing gallium and bismuth. The steel achieved an improvement of 229% in hardness and a 50% increase in tensile strength. Some slight decreases in thermal conductivity and diffusivity occurred as a result of the development of bainite in austempered steel, which affected the thermal behavior of the material. Through the process of bismuth diffusion into the steel grains, phase hardening was improved. To accomplish this, maintaining carbide stability and encouraging uniform carbon distribution were key. 500 °C was the best choice for austempering, where improved mechanical qualities were equally balanced. With its enhanced tensile strength, lightweight applications are now within reach, and the steel's enhanced hardness makes it perfect for uses requiring high durability and resistance to wear. This research emphasizes the potential of molten Bi-Ga austempering to enhance the performance of low-alloy steel across several industrial applications.