Study On Strip Surface Morphology Transfer Mechanism In Hot Strip Rolling Process

As an increasing number of hot rolled steel products are directly applying in the market,special requirements are put forward for the surface morphology of high quality hot rolled steel plates such as automobile and household appliance panels,tin plates and other coated steel plates.The surface topography of strip steel determines the light reflection effect of strip surface and the adhesion capability of coating layer and the oil storage in the process of stamping forming.Therefore,the quality of surface topography became a key parameter to determine the quality and service performance of strip steel products.In this thesis,the surface morphology transfer and change of strip steel in hot rolling process were investigated by theoretical analysis combined with numerical simulation,in order to satisfied the different users’ requirements on strip products.Based on fractal theory,the finite element theory and modeling process were introduced,finite element software ABAQUS was used to establish a single rough peak transfer process model to simulate the rolling process under single rough peak.Based on the measured process data of 1580 hot rolling line,the thermal coupling three-dimensional finite element model was established and the rolling process models containing single rough peak and multiple rough peak were established respectively to simulate the rolling process.Combining with the field conditions and rolling theory,the influences of several parameters on the transfer mechanism of plate and strip were analyzed,and the influences of process parameters such as rolling reduction,rolling speed and temperature on the transfer mechanism were emphatically studied.The experiment of hot rolling was carried out by laboratory rolling mill to measure the surface roughness of strip steel after rolling,and the simulation results were verified.The results show that with the increase of the reduction amount,the surface roughness value of the outlet strip also increases,indicating that large reduction amount was conducive to the copy of roll surface topography to the strip.With the increase of rolling speed,the surface roughness value of the outlet strip first increases and then decreases,showing a curve form,indicating that the high speed was not necessarily conducive to the copy of roll surface topography to the strip.With the increase of rolling temperature,the surface roughness value of the outlet strip also increases,indicating that high temperature was conducive to the copy of roll surface topography to the strip.