STUDIES ON STRETCHED ZONE WIDTH (SZW) AND FRACTURE TOUGHNESS IN LOW CARBON STEELS

Abstract

The technological advancement in aerospace, nuclear, piping and oil tanker industry has put stringent demand on structural components leading to widespread failure. These failures often are catastrophic with serious consequences on important aspects of life like economy, ecology and safety. Fortunately, some of the potential dangers due to increasing technological complexity may, in many cases, be reduced or avoided through better understanding of materials. Earlier, the design engineers used the flow behavior of ductile materials under uni-axial loading as the basis of design although for brittle materials, the preexisting crack used to be taken into account. Cracks and crack like defects exist in both the brittle and the ductile materials, which escape attention because of size limitation of detection ability of different quality control methods. It is also well known that these defects often initiate at non-metallic inclusions or at casting, forging and welding defects and propagate rapidly causing structural failure. There are certain similar defects, which may remain benign and does not contribute to failure. The identification of potentially dangerous defects and the condition under which these defects start propagating, has become the focus of research in fracture mechanics and this knowledge is being increasingly incorporated in our approach to design and quality control.