EBSD Analysis of HAZ Microstructure Characteristics of a High Strength Low Welding Crack Susceptibility Steel
This paper discussed the variation of microstructure at different locations of heat affected zone (HAZ) of a high strength steel welded joint using an optical microscope and an electron backscattered diffraction (EBSD) system. The results revealed that the change of microstructure plays an important part in the toughness properties at different locations of the HAZ. the CGHAZ (coarsen grain HAZ) microstructure contains granular bainite with the large effective grain size and a number of rod-like M/A constituents, which provide the nucleation sites and linear propagation path for micro-crack, therefore, this location becomes a local brittle zone. However, in the FGHAZ (fine grain HAZ) due to the microstructure mainly consisting of fine quasi-polygonal ferrite with high density of high angle grain boundaries, which can act as obstacles to cleavage propagation, the FGHAZ (fine grain HAZ) toughness is more excellent than the CGHAZ toughness.
Zhengyi Jiang, Jingtao Han and Xianghua Liu
L. Y. Lan et al., "EBSD Analysis of HAZ Microstructure Characteristics of a High Strength Low Welding Crack Susceptibility Steel", Advanced Materials Research, Vols. 152-153, pp. 852-855, 2011