EFFECT OF TEMPER EMBRITTLEMENT AND SPECIMEN SIZE ON CHARPY IMPACT TESTING OF A Cr-Mo-V ROTOR STEEL

摘要

Full and sub-size Charpy V-Notch specimens from several locations of a high pressure/intermediate pressure Cr-Mo-V turbine rotor were tested. A comparison between full and sub-size impact energy data showed that the smaller specimens exhibited qualitatively similar behaviour, with a systematic reduction in fracture appearance transition temperatures (FATT). The full and sub-size impact energy data was normalised against the specimen area and volume. The latter normalisation produced the closest match and the offset between the two data sets was described by a simple linear equation. The sensitivity of impact energy and FATT to specimen size was examined in samples possessing different degrees of temper embrittlement. It was found that the difference in FATT between full and sub-size specimens for embrittled samples was at least double that of de-embrittled samples.