Session: MF-03-01: Welding Residual Stress and Distortion Simulation and Measurement - 1

Paper Number: 84798

84798 - Electron Beam Welds in 316L Part 2: A Methodology and Example for Parameterised Residual Stress Profiles 

There is enthusiasm for new 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 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.

Paper 1 presented a suite of experiments was undertaken to measure residual stresses in a number of 316L austenitic stainless steel weldments. These measurements have been used to validate a modelling approach for a range of thicknesses, weld parameters and yield stresses and is used to investigate the parameter envelope in modelling space. The resulting dataset is presented and used to fit parameterised residual stress profiles through the thickness of the welds at the weld centreline.

An additional benefit of realistic parameterised weld residual stress profiles is the ability to use them in the development of probabilistic assessments, where a large number of cases may need to be considered across the parameter space. In the development of these profiles, trends have been observed between surface and peak stress magnitude and residual stress triaxiality. The former could reduce non-conservatism from the use of surface/near surface residual stress measurements, and the latter affects the constraint levels within the weld.

Presenting Author: Graeme Horne Frazer-Nash Consultancy

Presenting Author Biography: Graeme Horne is a Consultant at Frazer-Nash Consultancy, with an academic background in residual stress measurement and prediction, and their contribution to fracture. His PhD was supervised by Prof David Smith and the University of Bristol.

Authors:

Graeme Horne Frazer-Nash Consultancy
Ben Elliott Frazer-Nash Consultancy
Andrew Moffat Solar Turbines Europe S A