TRANSFORMATION INDUCED SUPERPLASTICITY IN 18Ni MARAGING STEEL

After exploring the influence of stress,cold-rolling reduction and cooling rate on transforma-tion induced strain,the transformation induced superplasticity forming technique of the 18Nimaraging steel(2450 MPa)was developed.Through 14 times γα′ cyclic transformation,thelimited elongation of 320% can be obtained in 60% cold-rolled specimen.TEM observationrevealed that the morphology of stress induced martensite is massive.