TWI Industrial Member Report Summary 970/2010
By L Wei
Clad components (eg piping and vessels), which are fabricated with corrosion resistant alloy (CRA) cladding on substrate materials, are widely used in various industries such as chemical and petrochemical processing, nuclear power and oil and gas. This is largely because cladding CRAs (typically austenitic stainless steels) have much better corrosion resistance compared with the ferritic steels used as base material, and thus protect the clad components from corrosive attack in a cost-effective way. However, there have been concerns over the structural integrity of clad components which primarily include: the introduction of residual stresses by cladding processes as well as by welding fabrications, the variation of microstructures in adjacency to the cladding interface, which in turn causes variations of fracture toughness within that area; the susceptibility to shallow sub-clad cracking, and the difficulty in detecting and sizing such flaws with non-destructive testing (NDT) methods.
In this report, a literature review is presented on the areas relevant to clad components from manufacturing and ensuing microstructural aspects of clad components, simulation and measurement of cladding residual stresses, and structural integrity assessments.
- Carry out a literature review on current clad components, with the focus on the issues related to evaluation of residual stresses in cladding through numerical and experimental approaches, and the implications of cladding on the structural integrity of clad components.
- Identify technology gaps with respect to clad components and provide the background information to define future research programmes.