Investigation of the Microstructure, Mechanical, and Wear Characteristics of the Boronized Layer on IN718 Alloy Treated Under Aging Conditions

Boronizing treatment has gained significant attention for its effectiveness in enhancing the wear resistance of IN718 alloy. However, conventional boronizing temperatures for IN718 are higher than its aging temperature, which can disrupt the aged microstructure and lead to degradation of mechanical properties. In this study, pack boriding was performed on solution-treated IN718 alloy in the aged condition (760 °C for 10 h followed by 650 °C for 8 h). The microstructure, mechanical properties, and tribological behavior of the boride layer formed on IN718 were systematically investigated. The boride layer, with a thickness of approximately 15 μm, was found to be primarily composed of CrB, Cr2B, Ni2B, and Fe3Ni20B6 phases. Following boronizing treatment, the surface hardness of IN718 was enhanced from 278 HV0.2 to 1938 HV0.2, with a concurrent significant increase in the yield strength of the bulk specimen. When sliding against a 440C steel counterface, the specific wear rate of the boronized sample was reduced by a factor of 49, and the friction coefficient decreased to 70% of that of the substrate. The dominant wear mechanism shifted from adhesive, abrasive, and oxidative wear for the untreated IN718 to abrasive and oxidative wear for the boronized specimen.