Variation of Mechanical Properties and Corrosion Properties with Mo Contents of Hyper Duplex Stainless-Steel Welds

This study investigates the effect of the Mo content on the mechanical and corrosion properties of hyper duplex stainless-steel welds that are subjected to flux cored arc welding (FCAW). Conventional hyper duplex stainless steel has limited productivity owing to the welding position and welding equipment of gas tungsten arc welding (GTAW) and submerged arc welding (SAW). As such, the purpose of this study is to develop a weld material for FCAW, which is not subject to the limitations of GTAW and SAW, as well as to improve productivity and quality. FCAW was performed under the same conditions, except for the Mo content, which were varied to 3, 4.5, and 6 wt%. Tensile and impact tests were carried out to investigate the variation of the mechanical properties according to the Mo content. As the Mo content increased, the elongation decreased and the strength increased. It was confirmed that the δ-ferrite phase increased and the γ-austenite phase decreased as the Mo content increased. Secondary phase such as σ phase, χ phase were mainly distributed in ferrite grains or austenite–ferrite grain boundaries using EBSD. It was also increased as the Mo content increased. To evaluate the corrosion resistance, Potentiodynamic Polarization Tests and DL-EPR tests were conducted. As a result, all of specimens showed similar corrosion resistance.