Measurement of residual stresses in T-plate weldments

Abstract

Tensile welding residual stresses can, in combination with operating stresses, lead to premature failure of components by fatigue and/or fracture. It is therefore important that welding residual stresses are accounted for in design and assessment of engineering components and structures. In this work residual stress distributions, obtained from measurements on a number of ferritic steel T-plate weldments using the neutron diffraction technique and the deep-hole drilling method, are presented. It has been found that the residual stress distributions for three different plate sizes are of similar shape when distances are normalized by plate thickness. It has also been found that the conservatisms in residual stress pro®les recommended in current fracture mechanics-based safety assessment procedures can be signi®cantÐof yield strength magnitude in certain cases. Based on the data presented here a new, less-conservative transverse residual stress upper bound distribution is proposed for the T-plate weldment geometry. The extent of the plastic zone developed during the welding process has also been estimated by use of Vickers hardness and neutron diffraction measurements. It has been found that the measured plastic zone sizes are considerably smaller than those predicted by existing methods. The implications of the use of the plastic zone size as an indicator of the residual stress distributions are discussed.

Stress Intensity Factors Due to Residual Stresses in T-Plate Welds

“…The material used in this case was a BS EN 10025 Grade S355 steel with average yield strength 358 MPa. These stresses have previously been reported in [1]. The measurement for the smallest (25 mm) weld is an average of a number of neutron diffraction measurements at a number of European facilities including Studsvik.…”

“…In order to make direct comparison between the distributions the distances have been normalised by plate width, W . As discussed in [1], it is seen that when distances are normalised by W , the stress distributions are similar to one another. Note that in addition to being of different plate thickness, these welds also have different design (the smallest is a fillet weld,the largest a partially pene- trating weld).…”

“…In order to reduce the neutron path length, relatively thin slices of the welds have been measured (13.5 mm). It has been shown in [1] by comparison with hole drilling measurements on a full thickness T-plate that, although such slicing reduces the out of plane (longitudinal stress), it does not have a significant effect on the in-plane (normal and transverse) stresses. A 2×2×2 mm 3 sampling volume was used and measurements were made at 28 locations across the specimen width.…”

A generic approach for a linear elastic fracture mechanics analysis of components containing residual stress

“…A bilinear distribution has recently been proposed [7] based on residual stress data for a range of T-plate joints in ferritic steels. This distribution, which has been obtained by shifting an approximate mean bilinear fit to the data by a uniform (membrane) stress of 0.25σ y .…”

An optimisation study of the modified deep-hole drilling technique using finite element analyses applied to a stainless steel ring welded circular disc

“…The DHD technique was successfully applied to very thick engineering components including 100mm (Brown et al, 2006), 175mm (Stefanescu et al, 2004), 300mm (Ohms et al, 2006) and 450mm thick (Hosseinzadeh et al, 2007a;Kingston et al, 2006). Furthermore it was successfully applied to locations which were difficult to access in thick components (Ficquet et al, 2005;Kingston and Smith, 2003;Wimpory et al, 2003a;Wimpory et al, 2003b).…”