Dynamic fracture behaviour of thermo-mechanically processed modified 9Cr-1Mo steel

Samples from normalized and tempered modified 9Cr-1Mo steel, were normalized at three different temperatures and rolled at four different temperatures and subsequently tempered. Samples were then subjected to instrumented Charpy impact tests. Impact properties were represented in terms of upper shelf energy, ductile-to-brittle transition temperature, 28 J energy transition temperature, general yield temperature, blunt-notched dynamic fracture toughness (Kjd) and reference temperature. Kjd was determined following the modified Schindler's procedure. Correlation between different transition temperatures and their conservativeness were analyzed in view of fracture safe design. Finally, microstructural parameters were related to the impact transition temperatures based on microstructural and fractographic studies.