Effect of the cooling rates on heat-affected zone of UNS S32304 duplex stainless steel welded by pulsed GTAW process

Two thin plates of UNS 32304 of duplex stainless steel were joined by pulsedgas tungsten arc welding (GTAW)usinga mixture98% of argon plus 2% of nitrogen as shielding gas orpure argon as purging gas at thebottom of the plate without filler metal.The temperature profile close and away from the weld pool was measured using Ktype(Ni-Cr) thermocouples, connected to a digital data acquisition system. The thermal cycleswas recorded in the heat-affected zone (HAZ)at a distance in between 1 and 3 mm from the joint line.The cooling rate and holding time were studied with respect to the used purging gas. Experimental thermal profiles are in good agreement with literature values. The joints welded without any purging gas revealed high peak temperature and cooling rates.The present investigation showed that temperature peaksare comprised in the phase transformationtemperatureranges for the welded duplex stainless steel.