Abstract This work aims to evaluate the effect of the number of welding passes and the thickness of ASTM A743 CA6NM martensitic stainless-steel plates on joints welded by the TIG process. Plates with 5 mm and 15 mm thickness were welded in a single pass and in eight passes, respectively. The filling material used was the ER410NiMo alloy, in the form of rods with a 2.4 mm diameter. Before the welding passes, the samples were preheated up to 150 °C. The characterization of the welded samples was performed with the aid of optical microscopy, scanning electron microscopy (SEM-FEG), electron backscatter diffraction (EBSD), and Vickers hardness. The experiments revealed that the sample welded in a single pass presented a higher amount of delta ferrite, with a network morphology, preferably located inside the weld bead and in the high-temperature (HT) heat-affected zone (HAZ). In the sample welded in eight passes, the delta ferrite presented different morphologies, preferably observed in the inter-pass regions, inside the weld beads, and in the high-temperature HAZ. Overheating in the inter-pass region resulted in HAZ width variation, which increased towards the bottom of the welded joint.
Santos et al. (Fri,) studied this question.