ANALISYS OF THE FRACTURE THOUGHNESS IN THE HEAT AFFECTED ZONE (HAZ) OF ONE HSLA STEEL

Abstract

The original contribution of the experimental research described here is intended to ensure that the KIC fracture toughness in the heat affected zone (HAZ) of USITEN 355 0.5 Ni Grade 1 steel produces a CTOD (?) (Crack Tip Opening Displacement) within the standard values, making the steel compatible with the welding procedure used and the heat energy supplied, which is 2 kJ/mm, in order to confirm that the grain size braking mechanism carried out by the microalloying agents (V, Nb, Al) of the base metal are working as intended. A further aim is to ensure, as far as possible, a correlation between the welding parameters and the results obtained from the fracture tests, in such a way that, should the results of the tests be unsatisfactory, the appropriate solution can be applied to the weld so that the parameters that govern the fracture tests are acceptable. The work developed here is useful as a guide and reference for future research on fracture mechanics in microalloyed steels. Keywords: HSLA, Fracture toughness, CTOD, HAZ, heat input energy, SMAW