Abstract
Cyclic thermal transient fatigue tests of dissimilar weld joints of SUS304 and 2.25 Cr-1Mo steels with Inconel 82 buttering were performed in order to study the general behavior of crack initiation and growth, including crack locations, directions and densities under the respective loading conditions. The crack initiation sequence at different parts of the test models corresponded well with the result of analytical prediction using the finite element method. The results suggest that counter bore machining near the buttering boundary with 2.25 Cr-1Mo steel must be kept sufficiently apart from the joint area. The allowable number of thermal transient cycles according to the ASME CODE CASE N-47 and the elevated-temperature structural design guide developed by the PNC (Power Reactor and Nuclear Fuel Development Corporation)was shown to have a considerable Safety margin compared with the crack initiation data of 1 mm in depth at all parts of the pipe models.
