Abstract
Mechanical properties of experimental nitrogen alloyed powder metallurgically produced duplex stainless steels were investigated. The microstructure of the studied powder metallurgically (PM) fabricated and hot isostatically pressed (hipped) duplex stainless steels was homogeneous and isotropic. The proportions of austenite and ferrite phases depended on the solution annealing temperature; the amount of austenite phase increased from 50 to 60% on lowering the solution annealing temperature from 1160 to 980°C. An increase in the oxygen content of PM hipped duplex stainless steels had a negative effect on impact toughness. Precipitation heat treatment of both copper containing and low copper content alloys between 350 and 550°C increased the tensile properties while maintaining impact toughness at a reasonable level. The mechanical properties of nitrogen alloyed PM hipped duplex stainless steels were equal to the properties of corresponding wrought duplex stainless steels or better.
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