Subcritical Crack Growth of a low alloy steel in gaseous hydrogen sulfide

1976 ◽  
Vol 10 (2) ◽  
pp. 121-128 ◽  
Author(s):  
D.M. Moon ◽  
J.D. Landes
Author(s):  
Yoru Wada ◽  
Yusuke Yanagisawa

Autofrettage is used to known as an effective method to prevent fatigue crack propagation of thick-walled cylinder vessels operating under high pressure. Since low-alloy steel shows an enhanced crack growth rate in high-pressure gaseous hydrogen, this paper aims to validate the effect of autofrettage on crack growth behavior in high-pressure gaseous hydrogen utilizing 4%NiCrMoV steel (SA723 Gr3 Class2). An autofrettaged cylindrical specimen with a 70mm inside diameter and 111mm outside diameter was prepared with an axial EDM (depth of 1mm) notched on the inside surface. The measured residual stress profile coincides well with the calculated results. The fatigue crack growth test was conducted by pressurizing the cylinder and varying the external water pressure. Crack propagation from the EDM notch was observed in the non-autofrettaged cylindrical specimen while no crack propagation was observed when the initial EDM notch size was within the compressive residual stress field. When the initial EDM notch size was increased, the fatigue crack growth showed a narrow, groove-like fracture surface for the autofrettaged specimen. In order to qualitatively analyze those results, fatigue crack growth rates were examined under various load ratios including a negative load ratio using a fracture mechanics specimen. From the information obtained, crack growth analysis of an autofrettaged cylinder in a high-pressure hydrogen environment was successfully demonstrated with a fracture mechanics approach.


2010 ◽  
Vol 50 (10) ◽  
pp. 1496-1502 ◽  
Author(s):  
Koichi Takasawa ◽  
Ryoji Ishigaki ◽  
Yoru Wada ◽  
Rinzo Kayano

1987 ◽  
Vol 109 (3) ◽  
pp. 340-346 ◽  
Author(s):  
J. D. Gilman

Analysis of fatigue crack growth data for low-alloy steel shows that the influence of cyclic frequency in simulated LWR environments can be interpreted as the superposition of a time-dependent, corrosion-assisted crack growth rate upon an increment predicted by a Paris law. The time-dependent component increases monotonically to a maximum of about 6×10−5 mm/s as stress cycling becomes more aggressive. A useful measure of aggressiveness is the average time rate of crack advance due to the Paris law component alone; i.e., AΔKn × frequency. The result suggests that current ASME Code methods for flaw assessment are highly conservative in some regimes of stress and frequency, but there is a possibility of growth rates well above the ASME XI, Appendix A curves in a very low-frequency, high-stress regime. An upper bound to the time rate of corrosion-assisted crack growth in low-alloy steel is well supported by the data. The threshold conditions for the onset of this high rate are less well defined and require further investigation.


Sign in / Sign up

Export Citation Format

Share Document