Enhancing tribological properties of pump shafts through shot peening: a study of surface roughness, hardness and performance comparison with heat treatment

Abstract This research employed Shot Peening (SP) to enhance the tribological behavior of the En-31 pump shaft material. The study compared the effects of varying peening pressures (2.5, 3, 3.5, and 5 bar) and shot sizes (S110 and S230) on surface roughness, hardness, and tribological behavior. Surface roughness was quantified using profilometry to assess the impact of shot peening on the topography of AISI 4140 steel, while hardness testing evaluated the enhancement in surface hardness post-treatment, correlating with the induced compressive residual stresses. Additionally, wear analysis conducted through tribological testing determined the effectiveness of shot peening and plasma nitriding in improving wear resistance under operational conditions. The results shown highest hardness of 12.5% was achieved at a pressure of 4 bar with the S230 shot material, while the surface roughness increased by over 75% under the same conditions. The 3.5 bar peening process produced the most significant improvements based on fractographic analysis.