Aluminum strip refers to sheet or strip made of aluminum as the main raw material and mixed with other alloy elements. Aluminum sheet or strip is an important basic material for economic development and is widely used in aviation, aerospace, construction, printing, transportation, electronics, chemical industry, food, medicine and other industries.
Aluminum Alloy Grades
Series 1: 99.00% or more industrial pure aluminum, good conductivity, corrosion resistance, welding performance, low strength
Series 2: Al-Cu alloy, high strength, good heat resistance and processing performance
Series 3: Al-Mn alloy, corrosion resistance, good welding performance, good plasticity
Series 4: Al-Si alloy, good wear resistance and high temperature performance
Series 5: AI-Mg alloy, corrosion resistance, good welding performance, good fatigue resistance, only cold working to improve strength
Series 6: AI-Mg–Si alloy, high corrosion resistance and good weldability
Series 7: A1-Zn alloy, ultra-high strength alloy with good toughness and easy processing
Aluminum cold rolling strip process
Aluminum cold rolling is generally divided into four parts: melting – hot rolling – cold rolling – finishing.
Melting and casting production process and its introduction
The purpose of melting and casting is to produce an alloy with a composition that meets the requirements and a high degree of melt purity, thus creating favorable conditions for casting alloys of various shapes.
The steps of the melting and casting process are: batching – feeding – melting – stirring and slag removal after melting – pre-analysis sampling – adding alloy to adjust the composition, stirring – refining – standing – furnace casting.
Several key parameters of the melting and casting process
During smelting, the furnace temperature is generally set at 1050°C. During the process, the material temperature needs to be monitored to control the metal temperature not to exceed 770°C.
The slag removal operation is carried out at around 735℃ , which is conducive to the separation of slag and liquid.
Refining generally adopts secondary refining method, the first refining adds solid refining agent, and the secondary refining adopts gas refining method.
Generally, it needs to be cast in time 30min~1h after the furnace is left to stand, otherwise it needs to be refined again.
During the casting process, AI-Ti-B wire needs to be continuously added to refine the grains.
Hot rolling production process and its introduction
1. Hot rolling generally refers to rolling above the metal recrystallization temperature.
2. During the hot rolling process, the metal undergoes both hardening and softening processes. Due to the influence of the deformation rate, as long as the recovery and recrystallization processes are not carried out in time, there will be a certain degree of work hardening.
3. The metal recrystallization after hot rolling is incomplete, that is, the recrystallized structure and the deformed structure coexist.
4. Hot rolling can improve the processing performance of metals and alloys and reduce or eliminate casting defects.
Hot rolled coil process flow
The process flow of hot rolled coil is generally: ingot casting – milling surface, milling edge – heating – hot rolling (opening rolling) – hot finishing rolling (coiling rolling) – unloading coil.
Milling surface is to facilitate hot rolling processing. Due to the oxide scale and casting fine structure on the surface, subsequent processing is prone to defects such as cracked edges and poor surface quality.
The purpose of heating is to facilitate the subsequent hot rolling process and provide a softened structure. The heating temperature is generally between 470℃ and 520℃, and the heating time is 10~15h, not more than 35h, otherwise it may be over-burned and coarse structure will appear.
Hot rolling production matters needing attention
The rolling passes for hard alloy are different from those for soft alloy. The rolling passes for hard alloy are more than those for soft alloy, ranging from 15 to 20 passes.
The final rolling temperature needs to be strictly controlled, as it directly affects subsequent processing and the physical and chemical properties of the finished product.
Alloy generally requires rolling edge during the production process.
The head and tail gates needs to be cut off.
The emulsion is a water-in-oil system, in which water plays a cooling role and oil plays a lubricating role. It needs to be kept at around 65°C all year round.
The hot rolling speed is generally around 200m/min.
Casting and rolling process
The casting and rolling temperature is generally between 680℃-700℃, the lower the better. A stable casting and rolling line will generally stop once a month or more to re-erect the plate. During the production process, the liquid level in the front box needs to be strictly controlled to prevent low liquid level.
Lubrication is carried out using C powder from incomplete combustion of coal gas, which is also one of the reasons why the surface of the cast and rolled material is relatively dirty.
The production speed is generally between 1.5m/min-2.5m/min.
The surface quality of products produced by casting and rolling is generally low and generally cannot meet the requirements of products with special physical and chemical properties.
Cold rolling production
1. Cold rolling refers to the rolling production method below the recrystallization temperature.
2. Dynamic recrystallization does not occur during the rolling process, the temperature rises to the recovery temperature at most, and the cold rolling appears in a work hardening state with a high work hardening rate.
3. Cold-rolled strip has high dimensional accuracy, good surface quality, uniform organization and performance, and can be produced in various states by heat treatment.
4. Cold rolling can produce thin strips, but it also has the disadvantages of high deformation energy consumption and many processing passes.
Brief Introduction to Main Process Parameters of Cold Rolling Mill
Rolling speed: 500m/min, high-speed rolling mill is above 1000m/min, foil rolling mill is faster than cold rolling mill.
Processing rate: Determined by alloy composition, such as 3102, the general processing rate is 40%-60%
Tension: The tensile stress given by the front and rear coilers during the production process.
Rolling force: The pressure exerted by the rollers on the metal during the production process, generally around 500t.
Introduction to the finishing production process
1. Finishing is a processing method to make the cold-rolled sheet meet the customer’s requirements, or to facilitate the subsequent processing of the product.
2. Finishing equipment can correct defects generated during the hot rolling and cold rolling production process, such as cracked edges, oil content, poor plate shape, residual stress, etc. It is necessary to ensure that no other defects are introduced during the production process.
3. There are various finishing equipment, mainly including cross-cutting, longitudinal shearing, stretching and bending correction , annealing furnace, slitting machine, etc.
Slitting machine equipment introduction
Function: Provides a continuous rotating shearing method to cut the coil into strips with precise width and less burrs.
The slitting machine generally consists of four parts: uncoiler, tension machine, disc knife and coiler.
Cross-cutting machine equipment introduction
Function: Cut the coil into plates with the required length, width and diagonal.
The plates have no burrs, are neatly stacked, have good surface quality, and have good plate shape.
The cross-cutting machine consists of: uncoiler, disc shear, straightener, cleaning device, flying shear, conveyor belt and pallet platform.
Introduction to tension and bending correction
Function: During the hot rolling and cold rolling process, the uneven longitudinal extension and internal stress caused by temperature, reduction rate, roll shape changes, improper process cooling control, etc. cause poor plate shape, and good plate shape can be obtained through stretching and straightening.
The coil has no burrs, neat end faces, good surface quality, and good plate shape.
The bending and straightening machine consists of: uncoiler, disc shear, cleaning machine, dryer, front tension roller, straightening roller, rear tension roller and coiler.
Annealing furnace equipment introduction
Function: Heating to eliminate cold rolling hardening, obtain the mechanical properties required by customers, or to make subsequent cold working easier.
The annealing furnace is mainly composed of a heater, a circulating fan, a purge fan, a negative pressure fan, a thermocouple and a furnace body.
The heating temperature and time are determined according to the requirements. For intermediate annealing, high temperature and fast speed are generally required, as long as butter spots do not appear. For intermediate annealing, the appropriate annealing temperature should be selected according to the performance of the aluminum foil.
Annealing can be done by either differential temperature annealing or constant temperature annealing. Generally, the longer the heat preservation time, the better the specified non-proportional elongation strength. At the same time, as the temperature rises, the tensile strength and yield strength continue to decrease, while the specified non-proportional elongation increases.
Post time: Feb-18-2025
