Enhanced Mechanostructure, Corrosion, and Tribological Properties of Incoloy-925 by Warm-Rolling Process

Abstract

In this study, the effects of warm rolling at 520 degrees C on the microstructure, mechanical, tribological, corrosion, and thermal oxidation behaviors of Incoloy-925 alloy were investigated. Plastic deformation applied at rates of 30, 50, and 70% led to a significant grain size reduction from 150 to 8 mu m, resulting in improved hardness (up to 339 HV) and yield strength (up to 1480 MPa). Wear tests showed that the coefficient of friction decreased from 0.653 (untreated) to 0.548 (70% deformation), and the total mass loss dropped from 7 to 1 mg. Corrosion analysis revealed that the corrosion rate declined from 6.94 to 1.02 mpy with the increase in deformation, attributing to enhanced passive film formation and a more homogeneous surface structure. TGA/DTA analyses confirmed that warm rolling improved thermal oxidation resistance. The mass loss decreased from 0.91% (untreated) to 0.49% (70% deformation). Exothermic reactions between 400 and 950 degrees C observed in DTA curves indicated phase transformations, which were consistent with XRD findings revealing gamma, delta, and MC-type carbide phases. Overall, the results demonstrate that warm rolling significantly enhances the surface integrity, thermal stability, and corrosion and wear resistance of Incoloy-925 alloy, making it a strong candidate for demanding industrial and biomedical applications.