Effect of microstructure on impact fracture behaviour of SUS304L SAW joint at low temperature

Abstract

The dependency of Charpy impact value (E _v) of SUS304L submerged arc weldment on test temperature and the angle (θ) between columnar structure and specimen has been studied. The distribution ofE _v in the weldment was also measured. The results were summarized as follows. (1) The impact value scarcely depends on the angleθ. (2)E _v of the weld metal decreases with decreasing the test temperature because the brittle fracture occurred along toδ ferrite. (3)E _v indicated a minimum value at the weld metal and increased drastically at the fusion boundary and reached a high value at the base metal. The variation ofE _v corresponds to the distribution of oxide inclusion and the change of morphology ofδ ferrite. (4) At low temperature, globular typeδ ferrite causes fine dimples, a discontinuousδ ferrite network causes large dimples, and continuousδ ferrite easily leads to brittle fracture along toδ.