Study On Deep Drawability Of Cold Rolled Sheet Based On CSP

Using CSP hot rolled sheet of Lianyuan Iron and Steel Co. as the rough material, the cold deformation experiment, the recrystallization experiment, the cold rolling and the annealing experiment have been carried out by usingФ180×200 two high rolling mill and SG-7.5-10 salt bath furnace and Pre-Vacuum furnace in the laboratory of Wuhan university of science and technology in this paper.Through the experiments of cold deformation and recrystallization, the situations of work-hardening and recrystallization were analysed, determining work-hardening curve of cold- rolled base plate, establishing the deformation desistance model, confirming the recrystallization temperature of CSP cold-rolled base plate and analysing the microstructure variation of cold deformation process and recrystallization process.Through the experiments of cold rolling and the annealing, the effect of cold-rolling reduction ratio on the deep drawability and microstructure of the cold rolled sheet were studied when cold rolling reduction rate is 50%,60%,70%,75%,80% respectively, the annealing temperature is 680℃and the holding time is 240min separately; the effect of annealing process on the deep drawability and microstructure of the cold rolled sheet were studied when the CSP hot rolled sheet was cold rolled and the total reduction rate is 70%, the annealing temperature is 680℃, the holding time is 240min and 360min respectively and the annealing temperature is 710℃, the holding time is 240min.The result indicated that the work-harding property of the hot rolled sheet that is used for cold rolled base plate under the condition of CSP according with the hot rolled sheet produced by the traditional long process line; the cold rolling and the annealing process are the important factors influencing the deep drawability of cold rolled steel sheet; for the studying steel type with the same annealing process, the nicer deep drawability is achieved at the reduction ratio of 75%; for the studying steel type, high annealing temperature contributes to improve the deep drawability of cold-rolled steel sheet when the cold rolling reduction ratio is 70%.