Fatigue crack growth in interstitially hardened AISI 316L stainless steel

Fatigue crack growth in interstitially hardened 316L stainless steel has been investigated in air and 0.6 M NaCl. Large compressive residual stresses introduced by “colossal” carbon supersaturation resulting from low temperature carburization increase the fatigue crack growth threshold from 8 MPa √m to 10 MPa √m, and retard the crack growth rate by a factor of two in the low stress intensity range. Fractography revealed no observable difference between the fracture surfaces of the bulk material and the hardened layer, either in air or the corrosive environment.

► Carburization-induced residual stresses improve fatigue behavior in air and NaCl.
► Low temperature carburization increases the fatigue stress intensity threshold.
► Low temperature carburization lowers the stready-state fatigue crack growth rate.
► Low temperature carburization also increases resistance to corrosion fatigue.