Study On Processing Technology Of Wide-width Pure Nickel Sheet

Pure nickel is widely used in aerospace,petrochemical,food,automobile parts,electronics electricity and many other fields due to its good thermal conductivity,oxidation resistance,strong corrosion resistance,good plastic processing and welding ability.But the preparation of Wide-width pure nickel sheet with large industrial consumption,especially the subsequent treatment after rolling,is lack of systematic and complete research.In this paper,the rolling research of two N6 billets produced by EB furnace smelting produced by Baoti Group was carried out on the 3.3m and 4 high reversible rolling mill.In the experiment,1300 kW furnace was used for heating,the first heating system was 950 ? / 8 h,and the deformation rate was about 70%.After rolling,the semi-finished slab is peeled,polished,and the four sides and defective parts are removed.After the surface inspection is qualified,the second rolling is carried out.The second heating system was 850 ? / 1.8-2.2 h,and the deformation rate is about85%.The effect of different pass deformation on the rolling forming and mechanical properties of wide N6 sheet was studied under the same total deformation.Three transverse and three longitudinal specimens were cut off from the rolled N6 sheet.The heat treatment experiments were carried out at 600 ? / 1h AC,640 ? /1h AC,680 ? / 1h AC,and then the tensile tests were carried out at room temperature.The effect of annealing temperature on mechanical properties of N6 sheet and thechange of microstructure of N6 sheet under different annealing temperature were studied.After straightening the annealed sheet,the process of removing the surface oxidation skin of N6 plate was carried out in a closed horizontal pickling machine with mixed acid solution of hydrofluoric acid and nitric acid.The influence factors on the surface pickling and surface quality of N6 sheet were studied experimentally.The above research provides reasonable rolling,heat treatment and pickling process parameters for the industrial production of N6 sheet.The main results are as follows:1.Under the same deformation amount,large pass deformation rolling is more favorable to the forming of wide N6 sheet,and the tensile strength and yield strength are obviously higher than that of the N6 sheet rolled by small pass deformation rolling.The final rolling temperature of N6 sheet should not be lower than 600 ?,otherwise,it is easy to appear the phenomenon of rolling warping and edge cracking.On the basis of the research in this paper,the wide N6 sheet(28mm × 2770 mm × 8820mm)with the largest single weight of 6.1 tons in the world has been successfully rolled.2.In order to meet the requirement of mechanical properties of annealed N6 sheet in GT/T2054-2013 standard,the suitable annealing temperature of N6 sheet should be chosen to in 600 ~ 640 ?,a narrow range after the inflection point,which can not only make the grain uniform and fine,Moreover,some adjustments can be made to make the strength and elongation of N6 plate match well.3.Under the continuous acid washing operation mode,the main factors affecting pickling effect and surface quality of N6 plate are: hydrofluoric acid concentration,nitric acid concentration,mixed acid ratio,pickling time,acid pickling temperature.Hydrofluoric acid concentration and pickling temperature are sensitive factors.The specific parameters of hydrofluoric acid,nitric acid concentration and their ratio,pickling time and pickling temperature are obtained.