GEN-3.2 Residual Stresses in Multi-Layer Component Welds

Monday, June 4, 2012: 9:35 AM
Cyperus 1 (Hilton Chicago/Indian Lakes Resort)
Mr. Michael Rhode , Federal Institute for Materials Testing and Research - BAM, Berlin, Germany
Arne Kromm , Federal Institute for Materials Testing and Research - BAM, Berlin, Germany
Thomas Kannengießer , Federal Institute for Materials Testing and Research - BAM, Berlin, Germany
Residual stresses in multi-layer component welds

 

For safety of welded joints in complex structures it is very important to know about the level and distribution of weld residual stresses. In recent studies the formation of residual stresses for simplified geometries was examined mostly for single layer welds. The transfer of the results to real welded structures incorporating shrinkage restraint is mostly difficult. A high level of shrinkage restraint causes increased residual stresses which have to be considered in the design of components with attention to the inservice behaviour.

To increase the transferability of existing models, multi-pass welds were examined. The welding experiments were conducted applying free shrinkage and also a defined restraint level using a special large scale test facility. This allows for comparison of the residual stresses in different stiffness conditions. Additionally, the reaction forces during welding and subsequent cooling of the individual weld runs could be analysed in-situ.

High strength steel specimens with a thickness of 50 mm were joined using Submerged Arc Welding. The occurring residual stresses after welding were determined by mobile XRD analysis for free shrinkage and defined restraint condition. The results show, that the level of the residual stress is strongly influenced by the restraint condition.  This applies for the weld, the HAZ and also the base material. Tensile stress maxima were predominantly found in the transition from the weld to the HAZ. Analysis of the occurring stresses during welding showed that the highest amounts were produced after completion of the last layer during cooling of the whole structure down to ambient temperature.