Effect of specimen size and material condition on the Charpy impact properties of 9Cr-1Mo-V-Nb steel

To evaluate the effectiveness of small specimens in measuring the relative shift in transition temperature and drop in upper-shelf energy, compared with a standard Charpy specimen, a study of the impact properties of 9Cr-1Mo-V-Nb steel in both the normalized and tempered and the quenched-only condition was conducted. Full-size and various subsize Charpy V-notch specimens of two orientations were examined in both material conditions. Comparing the test results of the tempered with the embrittled 9-Cr-1Mo-V-Nb steel showed that larger transition temperature shifts and smaller fractional drops of upper shelf were measured with the small specimens relative to the standard-size specimens. Attempts were made to improve the correspondence of data by fracture area and volume normalization. No improvement in the shift or shelf drop was obtained. However, a fair agreement for the higher energy tests of absolute energy was obtained with fracture volume normalization