MECHANICAL-PROPERTIES OF POWDER-METALLURGY DUPLEX STAINLESS-STEELS

Mechanical properties of experimental nitrogen alloyed powder metallur gically produced duplex stainless steels were investigated. The micros tructure of the studied powder metallurgically (PM) fabricated and hot isostatically pressed (hipped) duplex stainless steels was homogeneou s and isotropic. The proportions of austenite and ferrite phases depen ded art the solution annealing temperature; the amount of austenite ph ase increased from 50 to 60% on lowering the solution annealing temper ature from 1160 to 980 degrees C. An increase in the oxygen content of PM hipped duplex stainless steels had a negative effect on impact tou ghness. Precipitation heat treatment of both copper containing and low copper content alloys between 350 and 550 degrees C increased the ten sile proper ties while maintaining impact toughness at a reasonable le vel. The mechanical properties of nitrogen alloyed PM hipped duplex st ainless steels were equal to the properties of corresponding wrought d uplex stainless steels or better.