A TOUGHNESS STUDY OF THE WELD HEAT AFFECTED ZONE OF A

Fracture properties of different microstructural regions of the heat affected zone (HAZ) of modified 9Cr-1Mo steel (tempered base metal, intercritical, fine grained, coarse grained with and without δ-ferrite) have been studied by Charpy impact test. Simulation technique is used to reproduce HAZ microstructures. The fine-grained region shows highest toughness and the coarse grained with δ-ferrite shows the lowest. The results have been analysed in terms of tensile properties and microstructural features. The inter particle distance seems to affect the energy absorbed up to fracture both in the tensile tests and Charpy impact test. The highest toughness is obtained for an optimum inter-particle spacing