MICRO-CRACK ANALYSIS IN THE STUDY OF FATIGUE FRACTURE IN THE HAZ IN THE HIGH YIELD STRENGTH MICRO-ALLOYED STEELS

Abstract

Various applications have been described in the literature for the High-Strength and Low-Alloy steels (HSLA) industry, analysing their use both in industrial and marine equipment and machines and in structures that require appropriate resilience values and toughness at low temperatures. For successful operation under conditions as large structures under extreme service conditions, it is essential to ensure the proper toughness both in base metal (USITEN 355 0.5 Ni Grade I steel) and in the heat-affected area of the weld. (ZAC). This research carries out Crack Tip Opening Displacement (CTOD) tests, showing, in this article, the first part of the test corresponding to fatigue pre-cracking and a summary table of the results of fracture toughness, to guarantee that, under the conditions which exist in welding, both the fatigue fracture values and the fracture toughness are acceptable by the applicable standards. Keywords: SMAW, weld line, CTOD, stress intensity factor, input heat energy, crack growth rate, fatigue fracture, fracture toughness