The effect of bainite in producing nano/ultrafine grained steel by the martensite treatment

作者：Zakerinia Hossein^*; Kermanpur Ahmad; Najafizadeh Abbas

来源：Materials Science and Engineering A-Structural Materials Properties Microstructure and Processing, 2011, 528(10-11): 3562-3567.

DOI：10.1016/j.msea.2011.01.067

• Martensite treatment
• Nano/ultrafine grained steel
• Bainite

The martensite treatment including cold rolling and subsequent annealing of microstructures with high percentage of martensite is one of the most effective thermo-mechanical methods for grain refinement in steels. In the present work, the effect of bainite phase on the formation of nano/ultrafine grained structure in a low alloy 0.2% C steel was investigated. The martensitic and bainitic-martensitic microstructures were first produced in the specimens by quenching in water and oil from the austenitizing temperature, respectively. The specimens were subjected to 90% reduction in thickness by cold rolling and subsequent annealing. The formation of the nano/ultrafine grained structure was discussed from the viewpoint of characteristics of the martensite and bainite starting structure. It was found that nano/ultrafine grained structures with similar hardness and mean ferrite grain size can be produced in both specimens by annealing 90% cold rolled specimens at 550 degrees C for 80 min. However, due to the lower hardness of the bainite phase, cold rolling of the bainitic-martensitic microstructure was much more facile than the martensitic one, resulting in no transverse cracks in the cold rolled specimen.

• 出版日期2011-4-25