Rolling contact fatigue perspective of damage mechanism in 3D printed 17–4 PH stainless steel

This work investigates the rolling contact fatigue (RCF) behaviour of as-built 17-4PH stainless steel produced by Laser Powder Bed Fusion (L-PBF). Cyclic twin-disc tests were performed under various lubrication (oil and water) and loading conditions (1400–2000 MPa) to replicate service-like stresses. Experimental results highlight the dominant role of lubrication in damage progression. Oil delays crack initiation and limits surface degradation, whereas water intensifies pitting and crack branching due to hydraulic pressurization. Fracture surfaces reveal fatigue-dominated mechanisms with limited influence from melt pool boundaries. Crack depth and morphology vary with contact stress and lubrication, showing that fluid entrapment significantly affects propagation. These findings support the development of tailored post-processing and lubrication strategies for enhancing the durability of AM components in rolling applications. • Water lubrication intensifies crack bifurcation and subsurface damage. • Oil reduces surface damage and delays crack initiation under cyclic loads. • Water lubrication increases surface roughness, exacerbating fatigue damage. • RCF damage includes pitting, spalling, delamination, and crack branching. • Hydraulic pressurization in water-lubricated cracks promotes shelling.