Microstructural analysis of Hastelloy C-276 under cryogenic machining

The surface integrity of machined components is significantly influenced by the grain size and microstructural evolution of the material. This study investigates the microstructural refinement and texture evolution of Hastelloy C-276 under cryogenic machining. The machining experiments were conducted under dry and cryogenic (cryo) conditions with varying cutting speed, depth of cut, and feed rate. The machined specimens were subsequently sectioned along the machining direction using wire electrical discharge machining at ∼6 mm thickness intervals for further analysis. Severe plastic deformation played a pivotal role in grain refinement, while X-ray diffraction (XRD) analysis was employed to evaluate texture evolution and intensity variations. The cryo-machining process imposed lower temperatures in the machining zone, facilitating the formation of a strong texture orientation with an intensity enhancement. The results further confirmed a 41% reduction in grain size and a texture intensity increase up to 11.875. The cryogenic condition also caused a 47% reduction in XRD peak intensity, confirming grain refinement through severe plastic deformation. These findings highlight the potential of cryogenic machining to improve surface integrity and microstructural stability of Hastelloy C-276 for demanding industrial applications.