Abstract
The standard conditions for stress relief annealing (SR-treatment) of welded structures such as pressure vessels are indicated by JIS or ASME code. However, application of these conditions to high quality thick plates seems to be unreasonable, since they require for such plates to simply keep higher temperature for longer time than acutally needed. This is partially due to the lack of sufficient knowledge on the effect of SR-treatment over the reduction of welding residual stresses, especially for thick plates.
This study is to develop some simple calculation method to accurately estimate residual stresses remained in a very thick plate after SR-treatment. In the 1st report, approximate equations were developed for the relaxation test both at changing and constant temperatures because of its similar stress relaxation phenomenon to that of SR-treatment.
In this report, this method is further developed and applied to SR-treatment of welded joints of very thick plates in more general stress states and boundary conditions. Using the various relations between stresses and strains at high temperatures, estimating equations are formulated in order to simply calculate transient and residual stresses in welded joints during and after SR-treatment. The results are compared with the highly accurate analytical result based on the finite element method. The both results show such a good coincidence that the appropriateness of the new method is confirmed.
