Stainless steel Bright and annealing (BA)
And the copper alloy is easily oxidized during the heat treatment. In order to prevent oxidation and improve the surface quality of the workpiece, it must be annealed in a protective atmosphere or vacuum, so-called bright annealing. The protective atmospheres commonly used in the heat treatment of copper and copper alloys are water vapor, ammonia decomposition, incomplete combustion and dehydration of ammonia, nitrogen, dry hydrogen and partially combusted gas (or other combustible gases). Can be selected according to the type, composition and requirements of the alloy.
Pure copper and white copper are not oxidized in a weak reducing atmosphere, and are most suitably protected by a combustion ammonia containing 2% H2 or a gas containing 2% to 5% H2 and CO incomplete combustion. Pure copper can also be protected by steam. In order to prevent hydrogenosis, when the oxygen-containing copper is annealed, the hydrogen content in the protective atmosphere should not exceed 3%, or heat treatment in a micro-oxidizing atmosphere as described above. Pure copper is also widely used for vacuum annealing. Bronze containing aluminum, chromium, niobium and silicon can achieve bright annealing only in a highly reducing atmosphere. The heat treatment (annealing or quenching) of beryllium bronze is usually decomposed by ammonia decomposition, but the undecomposed part of ammonia should not exceed 20%, otherwise bubble problems may occur.
Brass with low zinc content can be brightly annealed, but bright annealing of brass with a content greater than 15% has not been resolved. This is because the decomposition pressure of zinc oxide is low, and ZnO can be formed in an atmosphere containing a slight oxidizing gas, and when it is heated to 450 ° C or higher, zinc starts to volatilize and dezincification of the brass. To overcome this disadvantage, it can be annealed under higher pressure conditions. The protective atmosphere used for brass is incompletely combusted gas, ammonia, water vapor, and the like. The protective atmosphere should be free of sulfur. The workpiece needs to be carefully cleaned before heat treatment, and there should be no oil or other dirt on the surface.
Different 2B and BA
BA (Bright Annealing) plate, the difference from the 2B plate is that the annealing process is different, 2B adopts the annealing and pickling combination process, and BA is annealed under hydrogen-protected oxygen-free environment. The rolling process and the finishing process of the two surfaces are also different.
The BA board is not used for wire drawing. If it is to be drawn, it is overkill and waste.
The 2B board is basically a matt surface, and the object can not be seen. The BA board is approximately mirror-like and can clearly illuminate the object (slightly paste).
Both 2B and BA can be polished into 8K mirror panels, but 2B requires more polishing steps, and BA can achieve 8K effects with just a fine throw. Depending on the final product, there are differences in whether or not BA is polished. Some BA products do not require polishing and are used directly.