Effect of loading history on stress corrosion cracking in high strength steel

摘要: Abstract The effect of preloading on crack nucleation time was examined with compact tension specimens having various notch radius in 0.1N-H 2 SO 4 aqueous solution for 200°C tempered AISI 4340 steel. Crack t n increases by a given apparent stress intensity factor K p . curve ϱ vs. deviates upward from the non case. A linear relationship between and parameter (2K /(πϱ) 1 −(2K ) th is seen semi-log diagram, where taken as value at = α due to preloading. threshold which detached nucleated some distance root extends form circle. This increasing load reduction during growth examined. When -value reduced , an incubation observed before started growing under -value. m tends increase ΔK - also found high reduction. In order explain these experimental results, new dislocation model proposed basis induced diffusion hydrogen region ahead or crack. suggests that change are caused reducing hydrostatic pressure spreading saturated requires more accumulation theory predicts experimentally relations − log ΔK.