Influence Of Annealing On Microstructure And Forming Performance Of AA5052 By High-throughput Continuous Casting And Rolling

High-throughput continuous casting and rolling process is a new type of high efficient aluminum alloy strip billet production process, the aluminum melt direct cast through feed into the high-throughput continuous casting machine, then roll to2-8 mm strip billet through three online hot tandem rolling technology. Process has advantages of high flow rate, short process, energy conservation and environmental protection. But AA5052 alloy plate is firstly produced by high-throughput continuous casting and rolling technology in our country, it’s product quality and recrystallization annealing process has yet to be researched; In addition, because the high-throughput continuous casting and rolling production line production process is a short process without the preheating homogenization process, there are always many problems such as surface defects and composition segregation,thus affect its bending performance of the final product. Therefore the analysis of the causes and mechanism is needed to carry on, and to formulate reasonable rolling heat treatment scheme.This paper was relying on the high-throughput continuous casting and rolling aluminum plate production line of a luo yang company, closely combine with the practical problems arising from the production line. We analyze the production line and microstructure and properties of the AA5052 alloy, and compare them with hot-rolled breakdown process, point out that the advantages and disadvantages of this 5 XXX series aluminum alloy process production; AA5052 plate is annealed at different temperatures to explore the recrystallization process of AA5052 alloy under the law, and the production of recrystallization annealing is process established; Also from the perspective of segregation is AA5052- H32 plank bending performance instability and mechanism analysis of the causes of the phenomenon has carried on the discussion, and finally determine the proper rolling and middle annealing process, ensure that the process under AA5052 alloy bend performance stability. The main results were as follows:The average grain diameter on the surface of the upper and lower AA5052 casting slab under high-throughput continuous casting and rolling process was 70.13 μm, the average grain diameter on the middle surface was 92.52 μm. The second phase particles distributed along the grain boundary. The surface area presents of hot rolled slab near was recrystallization organization, the center was a long strip rolling tissue types, the second phase on surface area distributed along the rolling direction.AA5052- H32 state product was mainly along the rolling to the broken plate surface of the second phase, it was general line. Compared with hot rolling the second phase particle number were more, and location of the sampling area was larger.AA5052 fibrous tissue of the aluminum alloy plate began to lift when the annealing temperature is 340 ℃, completely disappeared when annealing temperature is 360 ℃. In the process, the mechanics performance degradation, plastic forming and greatly of plate improved the performance.The recrystallization annealing process for high-throughput continuous casting and rolling AA5052 material was: 360 annealing temperature℃ and insulation 2 h.The casting speed of high-throughput continuous casting and rolling process was very fast, and AA5052 aluminum alloy solid-liquid two phase zone was longer, jointly influenced the process of AA5052 alloy solidification process. Eliminating the preheating homogenization process, can not eliminate composition uneven and segregation of casting slab, the middle layer segregation content would launch a "genetic" as the rolling sheet to the finished product, so the finished plate bending performance showed unstable phenomenon.The change in the late of rolling and middle annealing process parameters method could improve the finished plate bending properties, the high-throughput continuous casting and rolling process AA5052- H32 aluminum alloy processing technology was determined as: 4.5 mm- 3.0 mm- 2.0 mm- 1.3 mm- intermediate annealing 480 ℃ x 8 h- 1.1 mm. According to the technological process, not only product performance was excellent, and could use the lower middle annealing temperature to achieve the same effect and cost savings.