1. Characteristics of hot rolling
Hot rolling generally refers to rolling performed above the recrystallization temperature of the metal. During hot rolling, the deformed metal has both hardening and softening processes. Due to the influence of the deformation speed, as long as the recovery and recrystallization process is too late, the metal will produce a certain degree of work hardening with the increase of the degree of deformation. However, in the hot rolling temperature range, the softening process plays a leading role. Therefore, at the end of hot rolling, the recrystallization of the metal is often incomplete, and the hot-rolled aluminum alloy sheet and strip show the coexistence of recrystallization and deformation.
Hot rolling has the following characteristics:
(1) Hot rolling can significantly reduce energy consumption and reduce costs. During hot rolling, the metal has high plasticity and low deformation resistance, which greatly reduces the energy consumption of metal deformation.
(2) Hot rolling can improve the processing performance of metals and alloys, that is, the coarse grains in the as-cast state are broken, the micro-cracks are healed, the casting defects are reduced or eliminated, and the as-cast structure is transformed into a deformed structure, and the processing performance of the metal is improved.
(3) Hot rolling usually adopts large ingot and large reduction rolling, which not only improves the production efficiency but also creates conditions for increasing the rolling speed and realizing the continuous and automation of the rolling process.
(4) Hot rolling cannot control the mechanical properties required by the product very precisely, and the organization and properties of hot rolled products are not uniform enough. Its strength index is lower than that of cold work hardened products but higher than fully annealed products; its plasticity index is higher than cold work hardened products and lower than fully annealed products.
(5) The thickness and size of hot-rolled products are difficult to control, and the control accuracy is relatively poor; compared with cold-rolled products, the surface of hot-rolled products is rougher, and the value of R is generally 0.5-1.5um
2. Product scheme and process flow
Hot-rolled products are generally divided into two categories, one is a hot-rolled thick plate, and the other is a hot-rolled coil. Hot-rolled thick plate refers to an aluminum alloy plate with a thickness of not less than 6.0mm. The main varieties are hot-rolled plate (H112), annealed plate (0), quenched or quenched pre-stretched plate, etc. It is produced by the block method, and its typical process flow is:
ingot (homogenization) → milling surface, edge milling → heating → hot rolling → shear interruption → straightening.
The aluminum alloy sheet with a thickness of less than 6.0mm is produced by the coil method. The main task is to provide billets for cold rolling. The process flow is:
ingot (homogenization) → milling surface, edge milling → heating → hot rolling (blank rolling ) → hot finishing rolling (coiling rolling) → unloading.