scholarly journals Influence of Temperature and Long Term Ageing on the Fatigue Crack Growth in a Precipitation Hardened Martensitic Stainless Steel

2013 ◽  
Vol 66 ◽  
pp. 226-232
Author(s):  
L. Dimithe Aboumou ◽  
G. Henaff ◽  
M. Arzaghi ◽  
S. Pommier
Keyword(s):  
Stainless Steel ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Martensitic Stainless Steel ◽  
Influence Of Temperature

Fatigue Crack Growth in a Precipitation-Hardened Martensitic Stainless Steel: Influence of Ageing, Temperature and Loading History

2014 ◽  
Vol 891-892 ◽  
pp. 961-966
Author(s):  
Loic Dimithe Aboumou ◽  
Gilbert Hénaff ◽  
Mandana Arzaghi ◽  
Sylvie Pommier
Keyword(s):  
Fracture Toughness ◽  
Stainless Steel ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Room Temperature ◽  
Martensitic Stainless Steel ◽  
Load Ratio ◽  
Fatigue Crack Growth Resistance ◽  
Variable Amplitude

The 15-5PH (precipitation-hardened) martensitic stainless steel is prone to embrittlement following ageing during service at temperatures between 300°C and 350°C. This results in an increase in strength and a decrease in elongation and fracture toughness. However little information is available on the consequences of long term ageing on fatigue crack growth resistance. In the present study this issue is precisely addressed at room temperature and 300°C, with different load ratio under constant amplitude loading and under variable amplitude loading.At room temperature, the results indicate a marginal effect of the load ratio, regardless of ageing conditions and temperature. While the Paris regime is not affected by ageing, a significant drop in the critical stress intensity value before unstable fracture is observed, reflecting a decrease in fracture toughness of the material with ageing. At 300°C, the FCGRs are higher than at room temperature for all ageing conditions. Variable amplitude loading tests carried out on differently-aged materials showed the same retardation effect.

Effect of Hydrogenated Water on Fatigue Crack Growth for Austenitic Stainless Steel in Simulated BWR Water Environment

2004 ◽  
Author(s):  
Li H. Wang
Keyword(s):  
Stainless Steel ◽  
Fatigue Crack ◽  
Cyclic Loading ◽  
Austenitic Stainless Steel ◽  
Fatigue Crack Growth ◽  
Water Chemistry ◽  
Crack Growth ◽  
Growth Stage ◽  
Transgranular Fracture ◽  
Cyclic Loading Condition

Fatigue crack growth rates (FCGR) of sensitized austenitic stainless steel (SS) were measured in simulated BWR water at 288 °C using compact tension specimens under different cyclic loading modes, including saw-tooth, trapezoidal and constant loading pattern. This study tested sensitized SS in normal water chemistry (NWC) and hydrogen water chemistry (HWC) respectively, and attempted to clarify the effect of low electrochemical corrosion potential on the FCGR of sensitized stainless steel. Significant environment effects on FCGR of sensitized stainless steel were observed in both water chemistries when compared with air fatigue curve. The pronounced suppression effect of HWC on crack growth in statically sustained load was not observed in cyclic loading condition. ASME curve doesn’t seem to be conservative and could not bound all the FCGR data tested in this study. In contrast, all of the measured FCGR data were bound by the JSME disposition curve. PLEDGE model proposed by General Electric reasonably predicted the FCGR of sensitized SS in NWC, but underestimated the FCGR in HWC. ANL’s superposition model successfully estimated the FCGR measured in both water chemistries. The fractography exhibited transgranular fracture mode during the crack initiation and growth stage. No differences in the appearance of fracture surface were observed in HWC and NWC. Only in very high DO environments, the sensitized 304 SS exhibited the mixed mode of intergranular and transgranular during growth stage.

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