Papers by Keyword: Severe Cold Rolling

Abstract: The effect of severe plastic deformation at ambient temperature on microstructures and mechanical properties of aluminum alloy 2519 was investigated by means of tensile test, micro-hardness test, optical microscopy and scanning electron microscopy. The results showed that tensile strength of as-queched 2519 alloy was greatly enhanced to nearly 550MPa (ultimate tensile strength, UTS) and 520MPa (yield strength, YS) by severe cold rolling or equal channel angular processing (ECAP) while the elongation decreased to 5%. The 2519 alloy could obtain quite well mechanical properties as much as 80 % and 12 passes cold rolling deformation. This indicated that pre-deformation by ECAP is effective in improving the mechanical properties of 2519 alloy by grain refinement, strain aging and high density dislocations.

Abstract: In this paper, the process of severe cold-rolling and annealing for Q235 steel with lath martensite has demonstrated a new promising technique for producing in-situ composite multi-nanolayer steel. Cold rolling and subsequent annealing have great impact on microstructure evolution as well as mechanical properties. In the as-rolled state, the strength (b 2112 MPa) is approximately four times increased than as-received material, which is attributed to work hardening and grain refining during cold rolling. As cold-rolled sample subjected to further annealing below 500 °C, deformed microstructure underwent further recovery and recrystallization and finally became refined equiaxed grains; ultrafine ferrite grains, nano-carbides precipitated uniformly were seen in the specimen annealed at 500 °C, and the phenomenon of fracture delamination was observed from the specimens, the delamination plane was parallel to the rolling plane, in-situ composite weak interfaces effect has great impact on the fracture surface. Annealing at and above 600 °C resulted in coarse ferrite grains with spheroidized coarse carbides, causing grain growth.

Abstract: 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.