Transformation controlled nitride precipitation hardening heat treatable steel

The invention relates to a transformation controlled nitride precipitation hardening heat-treatable steel with 15-18 wt. % chromium. The steel has a combination of strength, toughness and resistance to stress crack corrosion, and can therefore be used to advantage in the chemical industry, transportation technology, power station technology, building technology, and in plastics processing. The invention relates to a transformation controlled nitride precipitation hardening heat-treatable steel with the following composition (data in wt. %): 15-18 Cr, max. 0.5 Mn, 4-10 Ni, max. 15 Co, max. 4 W, max. 4 Mo, 0.5-1 V, at least one of Nb, Ta, Hf and Zr totaling between 0.001-0.1, 0.001-0.05 Ti, max. 0.5 Si, max. 0.05 C, 0.13-0.25 N, max. 4 Cu, rest iron and usual impurities, under the condition that the weight ratio of vanadium to nitrogen V/N is in the range between 3.5 and 4.2. The invention also relates to a heat treatment process for this steel. Very good strength, ductility and also corrosion resistance can be attained.