Metal cladding plate is composed of base steel (plain carbon steel) and composite layer (corrosion resistant metal) through the explosion and rolling process. The base material can be ASTM A 516 Gr70, ASTM A36, ASTM A283, ASTM A387 and other ordinary carbon steel and special steel. The cladding material can be ordinary stainless steel such as 304, 304L, 316L, S31603; Commercial pure titanium Gr1, Gr2, titanium alloy Gr.5, etc. Duplex stainless steel like 2205, 2507,904L; Nickel alloys such as Hastelloy C-276, C-22, Monel 400, Inconel600, Inconel 825, etc and other metal like Copper and Aluminum, etc. Metal cladding plate offers good process performance and can be hot pressing, cold bending, cutting, welding.
In theory, all kinds of malleable, corrosion-resistant and high-strength specialty metals can be used to make cladding materials. Cladding plates reduce the use of precious metals, their material and thickness can be produced by demands, combined the advantages of low cost and high performance. It has been widely used in petrochemical, coal chemical, fluorine chemical, fine chemical, acetic anhydride, PTA, chlor-alkali, salt, metallurgy, medicine, electric power and other fields. There are two main methods for industrial production of metal cladding plates: explosive cladding and hot rolling cladding.
Also known as explosive welding. superimposed the cladding layer on the base layer to make them keep a certain distance. The explosive instantly produces huge energy, which causes these two metals to collide at high speed to form plastic deformation, melting and welding together. Ideally, the shear strength per square millimeter can be up to 400 Mpa, which can meet almost any processing requirements.
The features of explosive cladding:
1. Cold processing, can produce a variety of metal cladding plate, such as titanium, copper, nickel, aluminum and a variety of non-ferrous metals.
2. Explosive cladding can produce metal with thickness up to hundreds millimeter for used in some large water conservancy project base and ultra-thick tube plate. It’t suitable for the production of composite steel plates with a total thickness less than 8 mm.
3. Less investment and can be small-scale production or mass production, also achieved a small number of pipe &plate or special-shape workpiece combination. The cladding layer can be spliced and polished before the explosion.
4. Due to the characteristics of explosives limited by weather and other technological conditions, explosive compound production efficiency is low. In addition, explosives can cause vibration, noise and smoke pollution, usually produces in the remote outdoor factory.
Hot rolling cladding
The hot rolling cladding is the process that the cladding material and the base material are overlapped and assembled into the slab to be rolled. In order to improve the bonding strength, a series of technical measures such as vacuum hot rolling or shielded gas rolling should be taken. The features of hot rolling cladding:
1. Using large plate mill and hot continuous rolling mill, so it offers high production efficiency and fast production speed.
2. More choice of product thickness, the stainless steel coating thickness of more than 0.5mm can be produced. Limited by the compression ratio of steel rolling, hot rolling production cannot produce a thickness of more than 50mm cladding steel plate, it is not convenient to produce round and other special shape clad plates.
3. Cladding plates of 6, 8 and 10 mm is ideal for this process. Under the condition of hot continuous rolling, the scale production can be realized and the length can be determined according to the needs to meet the needs of users.
4. Limited by technical conditions, the hot rolling process to directly produce titanium, copper, aluminum and other non-ferrous metal composite need to be improved.
Both explosive and rolling cladding are in accordance with GB/T-8165-2008 standard, by which main technical indicators are the same or higher than the Japanese standard JIS G3601-1990. They specified in different standards for pressure vessels. From the terms of cost accounting, the rolling cladding is calculated by ton while explosive cladding is calculated by explosive area. Some engineers concluded that from the actual production: with the limit of 20mm, the thick steel plate should be explosive composite while the thin steel plate should be rolled composite.