ELECTRON BEAM WELDS IN 316L PART 1: WELD PRODUCTION, RESIDUAL STRESS MEASUREMENTS AND PREDICTIONS

There is enthusiasm for new civil nuclear plants in the UK to adopt power beam welding technologies, which could offer several advantages over conventional techniques. In particular, reduction in the time taken to produce and inspect a weld, and thus the cost of manufacturing components. However, a blocker to the adoption of these technologies is a shortage of accepted methodologies for demonstrating the integrity of these joints, which forms part of the requirements of the generic design assessment within the UK regulatory environment. Residual stresses can contribute towards crack driving force and thus should be accounted for when assessing the integrity of a component or its tolerance to damage. Whilst bounding residual stress fields are often used, it is often desirable to have more realistic estimations that capture the through-wall residual stress distribution, which also allows them to be decomposed into membrane, bending and self-equilibrated components to aid stress classification. Material-specific weld residual stress profiles already exist, for example Level 3 profiles in the UK's R6 procedure. However, they are for arc welding techniques. This work seeks to provide a framework for the generation of weld residual stress profiles for power beam welds and is split over two papers: 1. Weld Production, Residual Stress Measurements and Predictions; 2. A Methodology and Example for Parameterised Residual Stress Profiles. In this paper an experimentally-validated programme of weld modelling is presented to be used as an input to the framework for producing parametric through-thickness weld residual stress profiles presented in the second paper.