SCC CRACK GROWTH RATES OF TYPE 304 STAINLESS STEEL AT HIGH K REGION IN SIMULATED BWR ENVIRONMENT

摘要

The stress corrosion crack (SCC) growth tests at high stress intensity factor (K) region onsensitized Type 304 stainless steel were carried out in 288 ℃ pure water using 50.8 mm (2-inch) thickcompact tension (2TCT) specimens. The purpose of this study is to clarify the crack growth rate at highK region taking into consideration of the specimen constraint condition. 2TCT specimens weremachined from 80-mm heavy thickness plate made of Type 304 stainless steel and were subjected to asensitization heat treatment. The crack growth rate at about 60 MPaf-m of 2TCT specimen was 1.5 to1.6 xl0 '7 mm/s at a corrosion potential of 40 mV SHE, which was less than a plateau region of the crackgrowth rate curve under normal water chemistry (NWC) condition proposed by Swedish utilities. Thecrack growth rate was reduced by about 1/5 by shifting the corrosion potential from 180 mV SHE to 40mV SHE at about 60 MPa,/-m. On the other hand, the crack growth behavior on 1TCT specimen underthe same K condition differed from the result for 2TCT specimen.