Corrosion of stainless steel tubes by liquid sodium systems, (2). Results and discussion for thermal convectional corrosion test

We have already discussed newly formed thermal convectional testing apparatus in high temperature NaK. NaK was circulated at a comparatively low flow rate in the time range from 500 to 1,500 hr at 600℃. We have mainly observed inner wall of the specimen tubes by microscopic examination. The results are as follow: (1) The shapes of inward deposited metals in tube are the most effective fact in this case. (2) At a low flow rate, there are changes for neither steel compositions nor welding methods after long exposure testing. (3) With the lapse of exposure time, microstructure of the specimens slightly differ from original state (especially deposited metal parts).