| Summary: | 碩士 === 國立臺灣科技大學 === 機械工程系 === 99 === The primary objective of this study is to investigate the stress corrosion characteristics of dissimilar metal welds (DMWs) comprising Type 316L stainless steel as the base metal and Alloy 82 as the weld metal in simulated boiling water reactor (BWR) environments. Slow strain rate tensile (SSRT) tests were conducted to explore the mechanical properties and stress corrosion cracking (SCC) behavior of the DMWs. Some DMW samples were pretreated by shot peening and thermal treatments at different temperatures prior to the SSRT tests, and the influences of these pretreatments on the samples were examined.
Test results showed that the mechanical property of the DMW sample did not exhibit any significant difference from that of a pure 316L stainless steel sample in the same environment. Furthermore, transgranular SCC was found on the fractured surface of the sample, but no intergranular SCC (IGSCC) was observed. A post-weld heat treatment at 650 oC slightly improved the ductility of the treated DMW sample during the SSRT test. A shot peening treatment aversely led to a more serious SCC on the treated sample with distinct traces of IGSCC. A pretreatment of solution annealing resulted in a much better performance as expected for the treated sample in terms of ductility and immunity to IGSCC, since the treatment helped relieved the residual stresses and led to a more even distribution of the alloying elements in the regions adjacent to the weld.
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