Investigation On The Roughness Of Plate And Strip Based On Crystal Plasticity Theory

As the car plate, galvanized plate, household appliances and other high value-added products are increasingly widely used, enterprises and scholars pay more and more attention to the surface quality of cold rolled strip. The existing research on the cold-rolled strip surface roughness mainly focused on the data collection on the production site, the data of the relationship between strip surface roughness and process parameters were obtained by the regression. In order to meet the needs of users’ different requirements about the strip, more in-depth research on the essence of surface roughness transfer and change in strip cold rolling process are needed. On the basis of existing research, discussing the relationship between the strip surface roughness and grain, the paper introduce the crystal plasticity theory to the study of roughness of rolled steel strip. In this paper, through the establishment of Voronoi polycrystal line model, crystal plasticity theory by ABAQUS secondary development will be introduced into ABAQUS to simulate the transfer and change of roughness in cold rolling process and analyses the influence of the process parameters. The main research contents and achievements of this paper are as follows.(1) The existing methods of establishing crystal model are compared. The formation process of Voronoi diagram similar to the process of nucleation and growth of grains, therefore adopting Voronoi polyhedron establish polycrystal model;(2) By studying crystal plasticity constitutive theory combined with the object of study to confirm the slip parameters, hardening rule, elastic parameters, incremental algorithm and iterative algorithm, ABAQUS user subroutine will be composed to simulate the strip surface deformation under crystal plasticity constitutive relationship;(3) Compared to the simulation results under classical elastoplastic constitutive relation and crystal plasticity constitutive relationship, coming to a conclusion that roll rough asperities and the pits left on the strip surface not completely fit as a result of pull drag phenomenon among crystal dislocation slip mechanism of plastic deformation viscoplastic constitutive;(4) Single asperity transferring process is simulated. Focus on the effects of reduction and rolling speed to the transfer of the roughness and effects of the grain size to the surface roughness of the cold-rolled strip. Through simplification and assumption to built a rolling model, the article study the effects of the reduction and rolling velocity on the roughness change.