Aa1235 Roll Casting Of Aluminum Foil Wool Of High Temperature Annealing And Double Zero Foil Ious Defects Of Research

The usage of CC (continuous casting) strip to produce two-zero alluminum foil has high efficiency, high-speed, and low energy-consuming,maintaining obivous advantages of economy. However, due to the technological characteristics of continuous casting,resulting in heterogeneous microstructure of the billet, a higher degree of supersaturation of solid solution and hardening rate. And also with the reduction of the thickness of alluminum foil, the influence of qualities and characteristics(such as segregation, coarse grain and other defects) of the strip on aluminum foil has become more direct and significant. Which means that investigation of controling or improving the microstructure of the CC strip, the evolution of metallographic and second-phase during the rolling process is of great significance. The purpose of this paper is to investigate microstructrue of AA1235CC strip which is provided by a China alluminum manufacturer. And the evolution of second phases and metallographic during high temperature annealling, the reason for "white stripe" defect existing in two-zero alluminum foil are also be studied. Propose a possible solution to this defect based on the previous research results. The main reseach details and results of the article are as follows:(1)The distribution of grain size and second phases are heterogeneous and non-equilibrium along the thickness direction. Surface layer is of deformed fibers, subsurface contains columnar grains mainly,and the center layer is composed ofcasting grains which also has experienced a little dynamic recovery and recrystallization. The surface layer contains less seconds phase particles than central layer because of the higher solid solubility it gets and center segregation. There’re so many metastable phases such as βp-FeSiAl, FeAlm/6/x in the strip as a result of rapid cooling and solidification during continuous casting. Along the thickness direction, surface layer contains more a-FeSiAl, but eutectic phases(Al-FeAlm/6/x) increase significantly in the central layer.(2)There’re some "bright samples" which are different from the "normal samples" existing on the surface of CC strip after the etching experience, it may due to the slow cooling of the strip’s center and chest regions during the continuous casting. The bright sample’s surface is composed of deformed fiber grains which are more coarse, resulting in it has got the higher intensity of Brass texture. However, the normal sample contains small grains which are similar to recrystallized grains because of higher cooling rate, and it alos has got high intensity of R or S texture.(3)The types and degree of phase transformations are influenced significantly by the temperature and cold rolling before annealling. With the increase of the degree of deformation and temperature, it will precipitate more FeAl3and the FeAl3will become more coarse which are harmful to the alluminum foil. As for the4mm cold-rolled plate, the recrystalliszed grains are more uniform and fine with the high annealing temperature of525℃. As the degree of deformation increases,recrystallized grain become finer, the distribution of second phases are more homogeneous.It’s worth to noted that, cold rolling before high temperature anealling will premote the precipitation of FeAl3, and its length will be over7μm when the thickness of the cold-rolled plate is less than3mm, under550℃/8h annealing condition.(4)The texture differences in the intensity between normal sample and bright sample continue to go through the coll-rolled and annealling state based on the factory production process. With the decrease of the thickness of alluminum plate, characteristics of "coarse grain" in the bright sample become more significant. As a result of the coarse grains are more anisotropic, its texture intensity is more lowwer. So there are white stripe defect on the two-zero alluminum foil under optical observation.(5)The increasement of deformation prior high temperature annealing will premote microstructure more uniform and finer, and the difference of texture between bright sample and normal sample become more identical. So it may solve the problem of white stripe in two-zero foil. However, cold-rolling will premote the precipitation of FeAl3, so the improved process is proposed:CC strip(6.5mm)â†'cold-rolled plate(2-3mm)â†'high temperature annealing(510-520℃/8h)â†'cold-rolled plate(0.6mm)â†'moderate temperature annealing(380℃/3h), and the annealing time can be reduced properly.