Study On The Resultant Force Determination And Pickling Model Of Oxidation Skin Of High Strength Steel For Vehicle

The hot-rolled high-strength steel plate must be washed by acid washing to improve the quality of the sheet before entering cold rolling,and reasonable pickling model can effectively improve the efficiency of pickling.Researchers have conducted extensive research on pickling models,but they all lack consideration of the factor of bonding force of oxide scale.Through research,it has been found that for automotive high-strength steels,the binding force of oxide scale has a significant effect on the pickling time and must be introduced into the pickling control model to accurately predict the pickling time.For this reason,the properties such as SEM,EDS,nano-scratch test,nano-indentation test and tensile test were used to test the morphology,composition and bonding force of oxide scale;the tension leveling model of high strength steel was established by the finite element method,and the feasibility of descaling and the effect of pulling parameters on descaling were verified;the end time of pickling was studied by theory and experiment,and the concept of potential derivative near zero method was put forward;influence factors of pickling were studied,and a comprehensive control model including high strength steel pickling acid temperature and concentration,oxide thickness,bonding force,acid liquid turbulence and peeling rate was established,and the influence of six factors on pickling efficiency was discussed by introducing orthogonal test.The results showed that the automotive high-strength steel oxide skin is generally two layers,the inner oxide scale is Fe3O4,and thickness is between 6?m and 26?m,the outer oxide scale is iron oxide,and thickness is between 6?m and 34?m.The shear bond strength between oxide scale and matrix is between 26 MPa and 38MPa.The simulation results show that proper pulling parameters can effectively achieve descaling effect and the reduction have significant effect on descaling.For the general high strength steel,when the potential derivative reaches-0.0025V/s,pickling was over,and the results of orthogonal test showed that the thickness of oxide scale has the greatest influence on pickling time,followed by acid liquid turbulence,oxide skin binding force,exfoliation rate,acid concentration and acid temperature.The research results of this paper have a reference for improving the quality of pickling of hot rolled automotive high-strength steels.