Investigation into Hydrogen Diffusion and Susceptibility of Hydrogen Embrittlement of High Strength 0Cr16Ni5Mo Steel

• Published in: Journal of iron and steel research, international international, 2015-10, Vol.22 (10), p.961-968
• Main Authors: SUN, Yong-wei, CHEN, Ji-zhi, LIU, Jun
• Format: Article
• Language: English
• Subjects: 0Cr16Ni5Mo steel; Applied and Technical Physics; Engineering; hydrogen diffusion; hydrogen permeation; Machines; Manufacturing; Material; Materials Engineering; Materials Science; Metallic Materials; Physical Chemistry; Processes; slow strain rate test; SSRT; thermal desorption spectroscopy; 慢应变速率; 扩散行为; 氢扩散; 氢脆敏感性; 缺口拉伸强度; 表观扩散系数; 高强度螺栓钢
• ISSN: 1006-706X; 2210-3988
• DOI: 10.1016/S1006-706X(15)30097-2

High strength bolt steel 0Crl6Ni5Mo was charged with hydrogen by means of electrochemical technique to evaluate the hydrogen diffusion behavior. The bolt steels were investigated by a combination of electrochemical hydrogen permeation, thermal desorption spectroscopy （TDS）, slow strain rate test （SSRT） and microstructure observation. The hydrogen concentration of both 10.9 grade （Rm=950-1 150 MPa） and 12.9 grade （Rm=1 150-1 250 MPa） bolt steels increases with increasing the hydrogen charging current densities and charging time. The 12.9 grade bolt steel has higher apparent diffusion coefficient than 10.9 grade steel, corresponding to the value of 4.7×10 7 mm^2/s. By means of TDS tests, the activation energies of the two experimental steels are 17.74 kJ/mol and 18.92 kJ/mol, respectively. The hydrogen traps of both grade bolt steels are dislocations and crystal lattice. The notch tensile strength of the steels is reduced with the hydrogen concentration carried out by SSRT. The fracture morphologies of the steels after hydrogen charging present ductile dimple and quasi-cleavage characteristic.