Effect of temperature on oxidation during boriding of Ni-Hard 4

Ni-Hard 4, also known as white cast iron, is widely used in many applications that demand high mechanical strength. This material is recognized for its ability to withstand challenging conditions. In this study, surface modification processes, particularly boriding, were carried out on the material. Boriding is considered an effective process for enhancing the mechanical strength of a surface. While there are various methods for performing boriding, the pack-boriding method was chosen for this study. This method was applied in a typical heat treatment furnace. Ni-Hard 4 specimens were subjected to different combinations of temperature (1000–1200 °C) and 4 h duration, resulting in a total of three distinct samples. Subsequently, the microstructure, hardness, and chemical composition of the boride layers formed on the material’s surface were meticulously examined. As a result of the detailed analysis, it was determined that if the boriding process was carried out in a furnace without controlled atmosphere, high temperature oxidation started on the surface of Ni-Hard 4, and in this case it increased in parallel with the increase in temperature.