Fatigue crack propagation in maragingsteel

Fatigue crack growth behaviour in different conditions of maraging (350) steel was studied at a stress ratio R = 0.1, at a constant applied stress level. The slope m in the Paris region was found to be almost the same in the annealed and aged conditions. At a stress intensity factor range ∆ = 30 MPa m^½, the aged material showed 82% higher growth rate than in the annealed condition. The inclusions had played a significant role in the fracture process.