Tribological behavior of directed energy-deposited 316L stainless steel and its ceramic reinforced composite under dry sliding conditions

Abstract

The dry sliding wear behavior of directed energy deposited (DED) 316L stainless steel and its TiB₂-ceramic reinforced composite (CRC) is investigated using a pin-on-disc tribometer and compared against wrought 316L alloy. The experimental results show that DED 316L exhibits the lowest wear rate among the three samples, followed by DED 316L + TiB₂ composite and the wrought 316L alloy. The morphologies of the worn-out surfaces indicate severe wear (characterized by deeper and wider abrasive groves) in wrought 316L, while mild wear in the case of DED 316L. A thorough examination of the subsurface deformation zones using a scanning electron microscope and electron-back scattered diffraction shows severe distortion of cells just underneath the wear surface and excessive rotation of the grains. Further, the nanoindentation experiments in the subsurface deformation zones reveal softening in the deformed layers of wrought 316L and DED 316L + TiB₂ samples. The cellular sub-grain morphology inherent to the DED 316L samples is found to be beneficial for wear resistance as opposed to the TiB₂ enriched cell boundaries of the DED 316L + TiB₂ composite. The results are discussed with reference to the microstructure, texture and prevalent wear mechanisms among the samples.