Tribological behavior of heat treated AISI 6150 steel

Abstract This research presents an experimental study on the tribological behavior and plastic deformation layer response of quenched-tempered AISI 6150 steel and austempered AISI 6150 steel under sliding with a ball-on-disk type apparatus. Worn surfaces were analyzed by micro-hardness, 3D profilometer, microscopy and scanning electron microscope (SEM). The results showed that the disk surfaces were hardened after tribo-tests due to fresh-martensite formation caused by frictional heating/self-quenching during the sliding tests. The wear loss of the disk specimens was due to smearing plastic deformation resulting in material pile-up along the wear track and debris inside the wear track. The quenched-tempered disk specimens generated more debris than the austempered specimens. The greater amount of wear debris in the quench-tempered samples led to more severe contact stresses between the ball and disk samples which accelerated the smearing of material. As the tempering temperature increases, more cracks were observed for all quenched-tempered disk specimens. More voids and cracks was developed in the near surface region of tempered martensite leading to accelerated material loss through smearing and delamination. Also, more plate-like wear particles were observed on the disks of tempered martensite due to greater surface and subsurface crack fomation and propagation.