Tests were performed on austenitic stainless steels. In order to investigate
thermal fatigue resistance of quasi-structural specimens, test facilities enforcing
temperature variations similar to those found under the operative conditions have been
developed. Multiple cracking networks similar to those detected during in-service
inspections have been reproduced. Experiments and simulations deal with crack initiation
and crack growth. In the case of multiple cracking simulation, a Skelton's modelling has
been used. A shielding effect between cracks is evidenced. It leads to a dramatic reduction
of crack growth rate. Such effect is also crucial for the crack network stability under
additional loading.