The variant selection in the transformation from austenite to martensite in samples of maraging-350 steel

Abstract

Experiments have been conducted to study the variant selection phenomenon in the transformation from austenite to martensite in maraging-350 steel. The transformation of austenite to martensite in maraging steels occurs at temperatures below 300 ◦C depending on the alloy chemical composition. The transformation to martensite in these steels occurs regardless of the cooling rate. In these steels, the reverted austenite presents the same crys tallographic texture of the mother austenite. Samples of maraging-350 were austenitized at 860 ◦C inside a furnace attached to a tension test machine and then cooled in the furnace until the temperature of 600 ◦C and 400 ◦C. At these temperatures samples were deformed by compression with 10% reduction in height. After deformation the applied force was removed and samples were cooled to room temperature in air. A second group of samples was sub jected to the same austenitization and cooled until 300 ◦C when it was applied a compressive stress with magnitude below the yield strength. With the force applied, the samples were air cooled to room temperature. EBSD analysis was performed in cross-section of samples to determine the influence of plastic deformation before the transformation and also the influence of a stress in the elastic regime in the selection of variants of martensite. Measured pole figures were compared with calculated ones using the phenomenological martensite transformation concept associated with Patel–Cohen model.