Analysis of 316H Creep Crack Initiation Data at 550℃ using A Crack Tip Constraint Parameter

Author(s):  
Seung-Ho Lee ◽  
Hyun-Woo Jung ◽  
Yun-Jae Kim ◽  
Kamran Nikbin ◽  
Robert A. Ainsworth
2016 ◽  
Vol 119 ◽  
pp. 320-332 ◽  
Author(s):  
Lianyong Xu ◽  
Xingfu Zhang ◽  
Lei Zhao ◽  
Yongdian Han ◽  
Hongyang Jing

Author(s):  
Catrin M. Davies ◽  
Noel P. O’Dowd ◽  
Kamran M. Nikbin ◽  
George A. Webster

A method to predict the time for creep crack initiation (CCI) from a stationary crack tip is presented. The method is relevant to situations where small scale yield or widespread plasticity conditions prevail on initial loading. Initiation is considered to occur at the attainment of a critical creep strain at a small distance from the crack tip. The model proposed here considers the integrated effects of creep strain accumulation as the stress distribution changes from that on initial loading (controlled by J) to the steady state creep stress distribution (controlled by C*). Material properties are chosen to represent Type 316H stainless steel at 550°C and plane strain conditions are considered. For the conditions examined, the CCI times predicted are significantly shorter times than those predicted using a steady state creep model.


2017 ◽  
Vol 114 ◽  
pp. 98-109 ◽  
Author(s):  
Lianyong Xu ◽  
Xingfu Zhang ◽  
Lei Zhao ◽  
Yongdian Han ◽  
Hongyang Jing

Author(s):  
Seung-Ho Lee ◽  
Hyun-Woo Jung ◽  
Yun-Jae Kim ◽  
Kamran Nikbin ◽  
Robert A. Ainsworth

Abstract In this study, to qualify the constraint effect on creep crack initiation, the correlation analysis between proposed constraint parameter Q’ using time-dependent creep crack-tip stress and creep crack initiation time variable Ai was performed. Ai implies the influence of constraint effect on creep crack initiation. The procedure to calculate the Ai and the Q’-parameter was presented. To evaluate various status of constraint effect, creep crack growth tests for twenty-one compact tension specimens of Type 316H stainless steel at 550°C were investigated. The results of correlation analysis explain the reason for the different initiation time at the same C* level in respect of constraint effect.


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