Original paper(Vol.46 No.6 pp.607)
Effect of high pressure hydrogen gas on crack growth of carbon steel
Fukuyama Seiji; Han Gang; He Jianhong; Yokogawa Kiyoshi
Abstract:The fracture toughness and fatigue crack growth properties of carbon steel (S35C) were investigated in 1.1 MPa argon gas and in high pressure hydrogen gas up to 9.9 MPa at room temperature. The effect of hydrogen on the crack growth was discussed. The results obtained are as follows;
(1) JIH value in hydrogen was smaller than JIC value in argon and decreased with increasing hydrogen pressure. The quasi cleavage fracture was observed on the surface fractured in hydrogen, but no stretched zone was observed.
(2) The fatigue crack growth rate in hydrogen was larger than that in argon and increased with increasing hydrogen pressure. The mixture of quasi cleavage fracture and intergranular fracture was mainly observed in hydrogen.
(3) The critical plastic deformation for the crack growth in hydrogen was smaller than that in argon. The cracks in hydrogen were propagated in forming the quasi cleavage or intergranular fracture instead of the stretched zone or striations in argon.
Key Words:carbon steel, fracture toughness, fatigue crack growth, hydrogen environment embrittlement, hydrogen embrittlement, fractography