Investigations on Surface Characteristics of Heat Treated Tool Steel after Wire Electro-Discharge Machining

In the material removal process, the workpiece surface undergoes various changes. The heat treatment process improves the material properties, whereas the white layer, which is a resolidified oxidized layer on the machined surface, affects the surface roughness and fatigue life of the component. In this work, the change in metallurgical properties and surface topography due to the heat treatment of AISI D2 tool steel after wire electro discharge machining (WEDM) is investigated. The test specimens were prepared by milling and then conventionally heat treated before machining with WEDM process. The surface characterization was conducted using a scanning electron microscope (SEM) and an X-ray difractometer. Additionally, surface roughness measurements and hardness test were also carried out. The observations based on microstructural changes and the droplets forming recast layer are found to influence the surface roughness, hardness, and white layer thickness of the wire electro-discharge machined surface of the tool steel.