The weld zone corrosion resistance and mechanical properties of duplex stainless steels are largely governed by the phase balance. A number of factors significantly influence the phase balance, such as control of interpass temperature and heat input, which also tends to have an adverse effect on welding productivity.

The objective of this work was to evaluate the effect of minimizing weld volume, and increasing productivity on the properties of AS 2205 duplex stainless steel for use in the construction of chemical carriers.

A two-pass submerged arc (SA) welding practice and a laser welding process were used to produce the desired conditions. Evaluation centered around the use of electrochemical accelerated corrosion tests (ASTM G150) to determine the critical pitting temperature (CPT) of the weld and parent material. A number of metallographic techniques were used to establish the phase balance and the chemical composition of the phases. This allowed a modified Pitting Resistance Equivalent (PRE) to be used in the overall evaluation.

It was found that there was very little significant partitioning between the austenite (g ) and the ferrite (d ) in the weld metal, due to the high cooling rates of the weld and the high dilution of the weld metal filler (where used). Both processes produced ferrite contents at the top end of the traditional acceptance range. This did not appear to have a particularly deleterious effect on the corrosion resistance.

Additional data from laser welded austenitic stainless steels have been used to extend the range of the measurements taken on the duplex stainless.