In equipment manufacturing, there are occasions that the base metal (BM) need to be hot or cold worked prior to welding. After welding, the components have to be submitted to a normalizing heat treatment in order to recover its original mechanical properties. In this work four different low alloy steel weld metals (WM) both in the as welded condition and after normalizing heat treatment have been studied. Optical and scanning electron microscopy were used to observe the WM microstructure. Tensile and Charpy V toughness testing and microhardness measurements were used to evaluate the WM mechanical properties. Results show that normalizing breaks the original columnar structure in the as welded condition to an equiaxial structure similar to the one of the BM. Due to low carbon content of the WM it was observed a high decrease on the tensile properties specially the yield strength after normalizing. In respect of toughness, the normalizing heat treatment was observed to increase the Charpy V energy, except for one WM where a great content of martensite-austenite-bainite constituent was formed. Opposite to others post weld heat treatments, normalizing modifies significantly the microstructure and the resulting mechanical properties of the WM. Although normalizing is always beneficial to the BM, care must be taken in order to select welding consumables.
Welding; low alloy steel weld metal; normalizing heat treatment
