WE Seminar: Julian Avila, Fracture toughness comparison between friction stir welds in two API-5L-X80 steels with different microstructures and compositions

University of São Paulo at São Carlos School of Engineering, Brazilian Nanotechnology National Lab

Abstract

Friction stir welding (FSW) offers attractive mechanical properties for pipeline steel applications; however, differences in weld properties related to parent materials have not been reported in the open literature. In order to establish whether the initial microstructure and mechanical properties of t API-5L-X80 steel base plate affects the microstructure and fracture toughness of a two- pass FSW joint, two steels fabricated with differences in microstructure and chemical composition were assessed by fracture toughness testing in different microstructural regions of the weld. Crack tip opening displacement (CTOD) tests were performed at 0, -20 and -40°C. The fracture toughness values were similar in the assessed conditions, where high values on average (CTOD >0.1 mm) at 0 ºC and -20°C were found. Finally, at -40°C all the assessed conditions suffered a further generalized drop in toughness; however, through-thickness notches located at the hardest zone presented CTOD values below 0.1 mm.

Bio

Doctor Avila received his B.S in Mechanical Engineering from University Autónoma de Occidente (Colombia) in 2008, the MSc in Materials Engineering from University of Valle (Colombia) in 2011 and a PhD in Mechanical Engineering from the University of Campinas (Brazil) in 2016. In the course of the master program, he studied the fatigue resistance of a magnesium alloy (AZ31B) welded by friction stirring (FSW). His PhD research was focused on the fracture mechanics of FSW welded joints of X80 API-5L steels. His research interests are in the areas of additive manufacturing, welding and joining, fracture mechanics and microstructural characterization and mechanical properties assessment.