Aiming at the problem of shape defects due to overcooling at the edges during laminar cooling of Q235B hot rolled thin gauge strip at coiling temperatures between 660-680 ℃,a predictive model for the width Sc of the low-temperature zone along the edges of a 2 250 mm hot rolling production line was developed,with a prediction error controlled within±6 mm.A finite element model of laminar cooling for hot rolled thin gauge strip was established to compare and simulate the temperature field across the width of the strip,the pro-portion of phase transformation,and the distribution of residual stresses under conditions of laminar cooling and uniform edge shielding strategies.The results indicate that during laminar cooling,a temperature difference of 300 ℃ between the edges and the middle of the strip causes rapid cooling at low temperatures,leading to the formation of bainite structure with a volume fraction of approximately 33.48％at the edges,accompanied by the generation of tensile and compressive stresses.By applying uniform edge shielding,the tem-perature difference between the edges and the middle of the strip was controlled within+15 ℃,eliminating edge bainite structure while reducing the difference in the volume fraction of ferrite phase transformation between the edge and middle from 18.6％to 5.11％,there-by making the phase transformation proportion and residual stress distribution more uniform,improving the cooling strip shape,and eliminating wave defects at the edges of the strip.
hot rolled thin gauge striplaminar coolingprediction model of low-temperature zone widthedge shieldingfinite element simulation
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