Microstructure and mechanical properties of friction stir welded 8 mm pipe SAF 2507 super duplex stainless steel

The microstructure and mechanical properties of 8-mm-thick friction stir welded SAF 2507 super duplex stainless steel pipe was examined. High-quality welds were successfully produced using polycrystalline cubic boron nitride (PCBN) tool, force control mode of 38 kN, travel speed of 50 mm/min, rotational speed of 200 rpm. Hardness and tensile tests were performed, showing hardness increase in the stir zone and failure on the base metal. Thermal simulation showed maximum global temperatures around 1176 degrees C, and different thermal cycles along the joint thickness, providing microstructural and mechanical differences along the welded joint. (C) 2018 Brazilian Metallurgical, Materials and Mining Association. Published by Elsevier Editora Ltda.