Evaluation of dissimilar joint properties between UNS S32750 and API X65

The excellent properties of super duplex stainless steels (SDSS) are mainly due to their balance of ferrite - austenite since this balance is highly likely to change during welding and undesirable phases can create. In this work gas tungsten arc welding (GTAW) process was used to join UNS S32750 SDSS to API X65 high strength low alloy (HSLA) steel. The properties of weldments were investigated by impact test, potentiodunamic and cyclic polarization tests. Zero resistance ammeter (ZRA) tests also were used for investigation of behavior of galvanic corrosion on weld metal – HSLA base metal. Results indicated that amount of austenite in weld metal was higher than SDSS base metal and did not created undesirable phases. Toughness of weldment was higher than base metals and corrosion behavior of weld metal was alike SDSS base metal and presented excellent corrosion resistance comparing HSLA base metal. The results of ZRA showed that HSLA eroded in galvanic couple weld metal – HSLA and mechanism of corrosion was pitting corrosion.