Friction and wear behavior of shot peened surfaces of 36CrNiMo4 and 36NiCrMo16 alloyed steels under dry and lubricated contact conditions

Tribological behavior of two alloyed steels subjected to shot peening was investigated, under dry and lubricated sliding. 36CrNiMo4 and 36NiCrMo16 alloy steels were investigated at block-on-disc sliding testing machine, and three different applied loads (10 N, 30 N, 50 N) and sliding speeds (0.25 m/s, 0.5 m/s, 1 m/s) were observed. Shot peened surfaces were compared to ground ones, from aspects of their micro hardness and friction and wear properties. Microhardness tests were realized for both steel materials, ground and shot peened samples. Shot peening increased hardness of the near surface layers with approximately 10% increase near the top surface, in comparison to ground surfaces. Both friction and wear properties of the investigated steels showed improvement after shot peening, especially under high loads and speeds for dry sliding and low speeds and high loads for lubricated sliding. For all test conditions, 36NiCrMo16 steel showed better wear resistance and frictional characteristics than 36CrNiMo4 steel. Shot peening produced lowering of the friction coefficient, as well as wear rate, in comparison with ground surfaces, in both dry and lubricated sliding and for both materials. Wear tracks exhibited severe abrasive wear, accompanied with adhesive wear, in all test conditions, but in case of lubricated sliding of shot peened surfaces, at the lowest speed and the highest load, wear tracks showed regions with mild wear also. Important result was significantly lower number of cracks, with smaller sizes within wear tracks of shot peened surfaces, in comparison with ground surfaces. (C) 2013 Elsevier B. V. All rights reserved.