TRIP 型超高強度複合組織鋼板の第 2 相の形態と引張特性

概要

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A relationship between retained austenite and second phase morphologies and the influences of these morphologies on the tensile properties have been investigated using a 0.17%C-1.41%Si-2.00%Mn TRIP-aided dual-phase steel containing retained austenite. (1) A large amount (above 10vol%) of retained austenite lay isolated in ferrite matrix and away from hard phase particle if austenite morphology in α+γ region during annealing is a network structure or a fine grained island. In the other case, the retained austenite film (below 5vol%) remained inside the hard phases and along these lath boundaries. This type of retained austenite was remarkably stabilized. (2) The retained austenite increased both the flow stress and the elongation. These relationships between tensile properties and retained austenite content were affected with the morphologies. (3) The influences of second phase morphology on flow stress appeared to be small in TRIP-aided dual-phase steel as compared to conventional dual-phase steel because of the retained austenite. While, the elongation considerably depended on the morphology. The network structure of second phase enhanced internal stress and strain hardening rate after most of retained austenite had transformed to martensite. The steel with fine-grained isolated particles exhibited the increased elongation since the void-formation at hard phase/matrix interface was suppressed as compared to the other type of steel.
1990-08-01