高張力鋼の水素ぜい化割れ挙動と破面形態の解析
1984 年 33 巻 365 号 p. 191-197
詳細
1984 年 33 巻 365 号 p. 191-197
The characteristics of fractured surface of SCM 435 steel due to hydrogen embrittlement were studied as a function of hydrogen content, stress intensity factor and crack propagation rate, and the following results were obtained.
(1) The fractured surfaces of steels having 115, 150 and 170kg/mm2 tensile strength revealed almost intergranular, while that of 100kg/mm2 steel showed quasicleavage.
(2) The grain size of intergranular facet was almost equal to that of prior-austenite. No segregation of Cr, Mo, S or P was recognized at the grain boundary from the observation by an X-ray microanalyzer.
(3) The surface fractured near KISCC was intergranular. However, its percentage decreased with increasing K value and the surface became quasicleavage at K value more than 80MNm-3/2.
(4) With increasing hydrogen content, both the crack propagation rate and the percentage of intergranular facet increased.
(5) The intergranular fracture was thought to occur at some portion of crack front at first during the crack propagation stage and the remained part of crack front was fractured in quasicleavage.
(6) The percentage of intergranular facet was thought to be determined by the hydrogen content at grain boundary.
