Influence of Heating Rate on Transformations in an 18 per cent Nickel Maraging Steel

Abstract

SOME observations were made of the effect of heating rate on the martensite (M)→austenite (γ) reversion in a 300-grade 18 per cent nickel maraging steel. These are discussed here with reference to dilatometry, although the conclusions drawn are based also on other sources. Heating rates varied from 0.0037° to 1,200° F/sec, and covered a much wider range than has been reported for alloys of this type¹. The composition of the material in wt per cent is as follows: 18.40 nickel, 8.86 cobalt, 0.60 titanium, 0.09 aluminium, 0.02 carbon, 0.04 silicon, 0.05 chromium, 0.06 vanadium, 0.008 sulphur, 0.007 phosphorus, 0.016 zirconium, 0.003 boron, 0.05 calcium (added). All specimens were initially in the annealed-martensitic condition.