Transformation Temperatures and Welding Residual Stresses in Ferritic Steels

Residual stress in the vicinity of a weld can have a large influence on structural integrity. Here the extent to which the martensite-start temperature of the weld filler metal can be adjusted to mitigate residual stress distributions in ferritic steel welds has been investigated. Three single-pass groove welds were deposited by manual-metal-arc welding on 12mm thick steel plates using filler metals designed to have different martensite-start temperatures. Their residual stress distributions were then characterised by neutron diffraction. It was found that a lower transformation temperature leads to a potentially less harmful stress distribution in and near the fusion zone. The experimental method is reported and the results are interpreted in the context of designing better welding consumables.