The Mechanism of Slow Crack Growth and Stress Corrosion Cracking in Austenitic Stainless Steel

CORROSION ◽  
1984 ◽  
Vol 40 (9) ◽  
pp. 487-492 ◽  
Author(s):  
Wu-Yang Chu ◽  
He-Li Wang ◽  
Chi-Mei Hsiao
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Stress Corrosion ◽  
Crack Growth ◽  
Stress Corrosion Cracking ◽  
Slow Crack Growth ◽  
Corrosion Cracking

Failure Probability Analysis Based on FRI Model for Stress Corrosion Cracking Growth Introducing Residual Stress Distribution by Weld

2012 ◽  
Author(s):  
Noriyoshi Maeda ◽  
Tetsuo Shoji
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Stress Distribution ◽  
Stress Corrosion ◽  
Crack Growth ◽  
Stress Corrosion Cracking ◽  
Failure Probability ◽  
Corrosion Cracking ◽  
Protective Film

Failure probability of welds by stress corrosion cracking (SCC) in austenitic stainless steel piping is analyzed by a probabilistic fracture mechanics (PFM) approach based on an electro-chemical crack growth model (FRI model, where FRI stands for “Fracture and Reliability Research Institute” of Tohoku University in Japan). In this model, crack growth rate da/dt, where a is crack depth, is anticipated as the rate of chemical corrosion process defined by electro-chemical Coulomb’s law. The process is also related to the strain rate at the crack tip, taking the small scale yielding into consideration. Compared to the mechanical crack growth equation like the power law for SCC, FRI model can introduce many parameters affecting the generation and break of protective film on the crack surface such as electric current associated with corrosion, the frequency of protective film break and mechanical parameters such as the stress intensity factor K and its change with time dK/dt. Derived transcendental equation is transformed into non-dimensional form, and then solved numerically by iterative method. The extension of surface crack by SCC under residual stress field is simulated by developing the stress distribution in polynomial form following ASME section XI appendix A. This simulation scheme is introduced into PFM framework to derive the failure probability of austenitic stainless steel piping in nuclear power plants to be used in developing a risk-informed inservice inspection (RI-ISI) program.

Evaluation of the Inter Granular Stress Corrosion Cracking Defects in Austenitic Stainless Steel Piping

2009 ◽  
Author(s):  
Remigijus Janulionis ◽  
Gintautas Dundulis ◽  
Renatas Karalevicˇius
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Stress Corrosion ◽  
Crack Growth ◽  
Stress Corrosion Cracking ◽  
Crack Size ◽  
Corrosion Cracking ◽  
Flaw Size ◽  
Primary Circuit ◽  
Service Inspection

The Inter Granular Stress Corrosion Cracking (IGSCC) is a dominant damage mechanism of the austenitic stainless steel. The primary circuit piping of RBMK type reactors is produced from austenitic stainless steel 08×18H10T. Defects in welded joints of pipes with nominal diameter of 300 mm were detected during In-service inspections [1]. Metallographic investigations defined that crack growth mechanism is IGSCC. The appearance of defects increases the probability of RCS piping failures of these pipes. A leak or break in RCS piping is not acceptable from safety and political (society risk) points of view. According this the evaluation of these cracks is very important for safe operation of this type reactor. The procedures for IGSCC crack evaluation consist of two parts. The first part is determination of the acceptable crack size for the component with crack, and the second part is the crack growth calculation. The acceptable flaw size provides information about the largest flaw size which component can tolerate without failure with accepted safety factors. The crack growth calculation determines how long does it take for the existing crack to reach the maximal acceptable size. The results of these calculations (acceptable crack size and crack growth) determine the further inspection schedule of the components with crack. The objective of this paper is the evaluation of the IGSCC defects detected during In-Service inspection in the primary circuit piping which outside diameter of piping is 325 mm, the wall thickness – 16 mm. Detected cracks were evaluated using method R6 [2]. The IGSCC crack growing analysis was performed using methodology presented in document [3]. The prognosis results were compared with crack data detected during In-service inspection. According analysis results were determined that the IGSCC defects detected during In-service inspection can be left without repairing for 1.5 years operation.

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