Assessment of creep crack growth due to stress relief
β Scribed by G.A. Webster; C.M. Davies; K.M. Nikbin
- Book ID
- 104018510
- Publisher
- Elsevier Science
- Year
- 2010
- Tongue
- English
- Weight
- 731 KB
- Volume
- 47
- Category
- Article
- ISSN
- 0020-7683
No coin nor oath required. For personal study only.
β¦ Synopsis
An analysis is conducted to predict stress relief cracking at 550 Β°C in notched compact tension specimens of Type 316H austenitic stainless steel. The specimens had been subjected to pre-compression to generate a tensile residual stress distribution at the notch tip. This stress distribution is represented by a uniform reference stress over the zone of tension ahead of the notch tip. Creep rupture and creep crack growth data alone are required and used to make the predictions. It is found that the shape of the crack growth curve is correctly predicted when mean data are employed. However, upper bound crack growth properties are required to accurately predict the actual extent of cracking. Sensitivity studies show that the amount of stress relief cracking predicted is relatively insensitive to the reference stress initially assumed to describe the residual stress distribution, since the reference stress relaxes to a magnitude that is almost independent of its initial value. Adoption of an initial reference stress equal to the ultimate tensile strength of the steel, when combined with mean creep rupture and upper bound crack growth properties, results in safe predictions that are not overly conservative. The analysis should only be regarded as reliable for small amounts of crack extension of less than the size of the tensile zone ahead of the crack tip.
π SIMILAR VOLUMES
An equation is derived for the crack growth rate under creep conditions. In the model, the propagation of a grain boundary crack is controlled by the plastic growth of cavities located in the grain boundaries ahead of the crack. It is assumed that the cavities grow by power law creep in the elastic