The effects of atomic hydrogen and flake on mechanical properties of a tyre steel

Abstract The effects of hydrogen and flake on the fracture toughness, hydrogen-induced delayed cracking (HIDC), impact toughness and fatigue properties of a tyre steel have been investigated. The results showed that there was no effect of flake and atomic hydrogen on the fracture toughness K IC . Atomic hydrogen could induce delayed failure under constant displacement. The threshold stress intensity factor of hydrogen-induced delayed cracking, K IH , decreased linearly with diffusible hydrogen concentration C 0 , i.e., K IH (MPa m 1/2 ) =  K IC  − 4.0 C 0 (ppm) ( C 0  > 0.5 ppm). Atomic hydrogen had no effect on impact toughness and fatigue properties when the C 0 was low ( C 0  ≤ 0.5 ppm). The flakes decreased impact toughness and caused it to fluctuate. Atomic hydrogen increased the fatigue crack growth rate when the diffusible hydrogen concentration was high enough ( C 0  ≥ 2.5 ppm). The flakes increased and undulated the fatigue crack growth rate.