Effect of internal hydrogen on the mixed-mode I/III fracture toughness of a ferrific/martensitic stainless steel

摘要

The effects of H on the mixed-mode I/III critical J-integrals (J(sub TC)) and tearing moduli (dJ/da) were examined for a martensitic stainless steel at ambient temperature. A H content of 4 ppm(wt) was attained after charging in a H(sub 2) gas chamber (138 MPa) at 300(degrees)C for 2 weeks. Results showed that H decreased J(sub TC) and dJ/da values compared to steel tested without H. However, the presence of H did not change the dependence of J(sub TC) and dJ/da values on the crack angles. Both J(sub IC) and dJ(sub 1)/da exhibited the highest relative values. The minimum values of both J(sub TC) and dJ/da occurred at a crack angle between 35 and 55(degrees) (P(sub iii)) /(P(sub iii)) + (P(sub i)) = 0.4 and 0.6. A mechanism of the combined effect of H and mixed-mode on J(sub TC) and dJ/da is discussed.