Session: MF-03-01 Weld Residual Stress and Distortion

Paper Number: 123545

123545 - Residual Stress Measurements and Modelling of Clad-Weld Interfaces 

Residual stresses from welding are often a significant loading in defect tolerance assessments.  Evaluation procedures such as R6 provide bounding Weld Residual Stress (WRS) profiles for typical component geometries which may be used if little or no information is available. However, these are often highly conservative, especially for components which receive a stress-relieving Post-Weld Heat Treatment (PWHT). 

Profiles developed from Finite Element (FE) modelling and/or WRS measurements may be used if they are available.  However, modelling can be time and computationally expensive and hard to verify and many measurement techniques are destructive so cannot be deployed on production items.  To address these limitations a combination of modelling and measurements is recommended in order to verify the modelling and to address any difference between the actual component and the test piece used for the measurements.

One area which has been identified as a gap in the literature is residual stress values at the intersection between a through-wall structural weld and internal weld-deposited cladding.  This paper presents modelling and measurement results from two such locations.  The first location is a low alloy steel pressure vessel circumferential weld that is subsequently clad using weld deposited Alloy 82.  The second is a nozzle to safe-end transition weld at which the ferritic portion of the nozzle is also clad.  Where possible results of both are presented before and after PWHT.

The modelling was carried out in Abaqus with axisymmetric models of the actual component geometry using the Abaqus Weld Interface, solid state phase transformation effects were not included.  Measurements were made using Deep Hole Drilling (DHD) at key locations in simplified but representative components that were manufactured as part of the weld qualification process.

At the circumferential weld there is good agreement in the shape of the predicted WRS profiles for both hoop and axial stresses.  The magnitudes are also similar, although the simplifying assumptions in the modelling generate some differences, particularly at the clad-parent interface.  A similar trend is seen in the safe-end weld.

Presenting Author: Benjamin Pellereau Rolls-Royce

Presenting Author Biography: Structural integrity specialist with many years' experience of design, fatigue and fracture assessment of nuclear components.

Authors:

Benjamin Pellereau Rolls-Royce
Robert Greensmith Atkins (Retired)
David Tanner Ministry of Defence
Mark Goulding Kent plc