Microstructure and mechanical properties of low carbon Al-killed steels after ultra-rapid annealing cycles

摘要

Ultra rapid annealing cycles were conducted on two low carbon Al-killed steel sheets differing mainly by their coiling temperatures (600°C or 700°C). For the lowest coiling temperature, the mean grain size of the steel was found to gradually decrease with an increase of the annealing temperature from 700°C to 920°C. A more complex grain size evolution was detected in the case of the steel coiled at high temperature. This led us to the conclusion that the size and the distribution of the iron carbides present before annealing, which is mainly governed by the coiling temperature, plays a very important role on the mechanisms involved in the grain refinement of extra-mild steels during ultra-rapid annealing cycles.