ANALYSIS OF MARTENSITIC TRANSFORMATION DURING TENSION OF HIGH MANGANESE TRIP STEEL AT HIGH STRAIN RATES

作者：Wang Lina; Yang Ping^*; Mao Weimin

来源：Acta Metallurgica Sinica, 2016, 52(9): 1045-1052.

DOI：10.11900/0412.1961.2016.00066

• high manganese steel
• martensitic transformation
• variant selection
• EBSD

Among the wide variety of recently developed steels, high manganese transformation-induced plasticity (TRIP) steels with low stacking fault energy (SFE) are particularly promising. Outstanding mechanical properties combining a high ductility and a high strength are then obtained. Compared to the static deformation of high manganese TRIP steels, the behaviors of martensitic transformation and mechanical properties of such steels during dynamic deformation may be different. In this work, martensitic transformation of high manganese TRIP steel at different strain rates was characterized by the EBSD technique. The volume fractions of austenite (gamma), hcp martensite (epsilon-M) and bcc martensite (alpha'-M) were calculated based on the XRD data. Meanwhile, variant selections of martensitic transformation in gamma ->epsilon-M and epsilon-M ->alpha'-M transformation were investigated by theoretical calculation. It is shown that orientation dependence of TRIP effect during tension exists even at high strain rates and can be ascribed to the influence of mechanical work in differently oriented gamma grains. The transformation of epsilon-M ->alpha'-M was promoted, but the total amount of transformed martensite decreased, which means that TRIP effect was restricted at high strain rates. The alpha'-M variant selection is more obvious during static tension and became weaker during dynamic tensile deformation. alpha'-M variant selection can be predicted by the calculated mechanical works induced by the local stress in <111>(gamma), and <100>(gamma) grains during static tension. However, during dynamic tension, the mechanism of variant selection needs to be explained by analyzing the mechanical works induced by the local stress, the strain energy and the interfacial energy in these grains comprehensively. Compared to the occurrence of a single alpha'-M variant, a pair of alpha'-M variants having specific orientation relationship reduces the strain energy, then unfavored alpha'-M variants appear.

• 出版日期2016-9-11
• 单位北京科技大学