On Preparation of In Situ Composite Steel with Ultra-High Strength and its Thermal Stability
A new type of in-situ composite nano-multilayer plate with ultra-high strength (b 2112 MPa), Q235 steel plate with nano-layered structure of lath martensite produced by severe cold-rolling, was developed. After cold-rolling, subsequent annealing has great effect on the deformed lath morphology and grain reﬁnement. Microstructure recrystallizing course have taken place after long time annealing at 350 °C. The recrystallization activation energy is 151 kJmol-1. Microstructure characteristics along rolling direction arrangement was decreased after annealing at 400 °C. In addition to the ultraﬁne ferrite grains, nano-carbides precipitated uniformly in the specimen annealed at 500 °C. Annealing at and above 600 °C resulted in coarse ferrite grains with spheroidized coarse carbides, causing grain growth. The average crystal size is about 4.7 m after annealing for 60 min at 600 °C.
Zhengyi Jiang, Jingtao Han and Xianghua Liu
J. Zhao et al., "On Preparation of In Situ Composite Steel with Ultra-High Strength and its Thermal Stability", Advanced Materials Research, Vols. 152-153, pp. 436-440, 2011