No abstract

No abstract

The STYLE EU Framework 7 project is examining the structural integrity of non-RPV components in reactor primary circuits. One of its focus areas is the impact of high magnitude weld residual stresses on the initiation and growth of cracks in austenitic stainless steels. A large scale fracture test has been performed on Mock-up 2, a butt-welded austenitic steel pipe containing a short, deep weld repair that induces weld residual stresses of yield magnitude over the length of repair. A through-thickness crack was introduced into the repair weld, and its behaviour under superimposed global bending load was investigated in a large scale fracture test. This paper describes the process of test design, the pre-test predictions made using the R6 defect assessment procedure, and the outcome of the test.

No abstract

Within the framework of European project STYLE [1], a fracture test on a pipe containing a through wall crack in a narrow gap Inconel Dissimilar Metals weld (welds named hereafter DMW) has been performed. The work is focusing on the Inconel - ferritic steel interface which is the weakest area of such welded pipes in front of ductile tearing. The study temperature is 300°C, which covers typical temperatures in components like hot pipes in the primary coolant system of pressurized water reactors. The four point bending test was carried out by the French Atomic Energy Commission and Alternative Energies (CEA), in order to study the mechanical properties and integrity of component such as the DMW pipes provided and designed by AREVA France. The observations made post-mortem showed a small 2.5 mm ductile tearing at the interface of Inconel and ferritic steel, and after this point, a large crack that has deviated from the interface to propagate in the Inconel and then in the stainless steel. The DMW Mock-up is presented with previous results concerning the mechanical characterizations of his constitutive materials. The second part of this paper is devoted to the four point bending test at 300°C: procedure, instrumentation and interpretation of large-scale test in terms of initiation and propagation of cracks. A comparison is made with tests performed at a smaller scale on multi-material CT specimens. The third part deals with first numerical analysis of fracture test. The results are interpreted on a small scale using finite element analysis to obtain the parameters of damage models that are needed for global approach. Finally, numerical approaches is presented and applied to simulate the fracture of the large-scale pipe. The aim of this paper is to propose and discuss the validity of new assessment methods of ductile propagation in a large scale pipe containing a through wall crack in a narrow gap dissimilar metal weld.