The Use of Neutron Diffraction for the Determination of the in-Depth Residual Stresses Profile in Weld Coatings

The neutron diffraction is a non-destructive technique, particularly suitable for the analysis of residual stress fields in welds. The technique is used in this article to study ferritic samples, coated by submerged arc welding using stainless steel filler metals. This procedure is often used for manufacturing process equipment for chemical and nuclear industries, for ease of implementation and economic reasons. The main disadvantage of that processes is the cracking phenomenon that often occurs at the interface between the base material and coatings, which can be minimized by performing post-weld stress relief heat treatments. The samples analyzed in this study were made of carbon steel plates, coated by submerged arc welding two types of stainless steel filler metals. For the first layer was used one EN 12 072 - S2 U 23 12 electrode, while for the second and third layers were used an EN 12 072 - 19 12 3 SL electrode. After cladding, the samples were submitted to a post-weld heat treatment for 1 hour at 620 degrees C. The residual stress profiles obtained by neutron diffraction evidence the relaxation of residual stress given by the heat treatment.