STRUCTURE-PROPERTY CORRELATIONS IN A COBALT-FREE MARAGING-STEEL

The precipitation hardening characteristics, grain growth behaviour, i nfluence of grain size (austenitising temperature) on the tensile prop erties and fracture toughness as well as the thermal embrittlement of cobalt-free maraging steel of 250 grade have been investigated to get a comparative assessment of this steel with respect to the standard 25 0 grade of Ni-Co-Mo maraging steel. It has been found that the tensile properties as well as toughness of the two steels are very similar af ter the same heat treatments. The precipitate is Ni3Ti in the present steel while it is Ni3Mo and Ni3Ti in the standard grade: The reverted austenite amount is less than that for the standard grade for a given ageing treatment. The grain coarsening behaviour as well as the therma l embrittlement aspects are common to both steels.