摘要
Low-carbon steel is widely used for household appliance and automotive panel steel because of its excellent plasticity.Unfortunately,yield point phenomena easily appear in the low-carbon steel produced by a continuous annealing process and cause degradation to the surface quality during processing.The effect of the coiling temperature(600-750℃)and annealing temperature(740-820℃)on the yield point behavior is studied.Tensile tests show that coiling temperature has a greater effect on yield point elongation(YPE)and aging index(AI)than the annealing temperature.Microstructure observations show that coiling temperature at 750℃would make the micron-sized carbides appearing at the grain boundary disappear and a number of dispersed nanoscale carbides precipitate in grain interior,corresponding to the highest solid solution carbon content in the matrix of 750℃coiled sample.The experimental results suggest that AI rather than YPE has a positive relationship with the solid solution carbon content of the low-carbon steel.And YPE has a positive relationship with the upper/lower yield strength.
基金
This work was financially supported by the Joint Fund of Iron and Steel Research(No.U1660103)
National Natural Science Foundation of China(No.51574162)
the National Key R&D Program of China(No.2018YFE0306102)
3DAP measurements were made in the Instrumental Analysis and Research Center at Shanghai University
The authors would like to express sincere thanks for their support.
