EFFECT OF MIXED-MODE OVERLOADS ON ENVIRONMENTAL-HYDROGEN-INDUCED FRACTURE

The effect of short periods of mixed-mode overloading on the environme ntal hydrogen induced fracture life of 0.42%C, 0.87%Cr, 0.21%Mo steel has been studied. Tests were performed in 0.5 mol/L H2SO4 solution und er continuous hydrogen charging conditions using a weight loading syst em. Experimental results show that the application of mixed-mode overl oads can cause more severe crack growth retardation than those of mode I. Possible mechanisms responsible for the retardation of subsequent crack growth, such as crack deflection, plasticity-induced residual co mpression stresses, dislocation shielding and overload damage, are exa mined.