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Clad steel plate is a bimetallic plate made of stainless steel, nickel base alloy, copper base alloy or titanium plate with pearlitic steel as the base, and by explosive welding, composite rolling, surfacing and other methods. So what are the key points of clad steel plate welding?
1. Welding method
When welding clad steel plates, welding methods such as electrode arc welding, submerged arc welding, tungsten argon arc welding, CO2 gas shielded welding and plasma arc welding are usually used. At present, tungsten argon arc welding or electrode arc welding are commonly used to weld the cladding, and submerged arc welding or electrode arc welding is used to weld the base course.
2. Groove form
V-shaped, X-shaped, V-shaped and U-shaped grooves can be used for butt joints. Machining can also be carried out at a short interval on the back of the joint to remove the clad metal, so as to ensure that the base weldment is not welded to the clad when welding the base weld bead. Generally, x-groove double-sided welding is adopted as far as possible, first welding the base layer, then welding the transition layer, and then welding the cladding, so as to ensure that the welded joint has good corrosion resistance.
At the same time, the welding characteristics of the transition layer should also be considered to minimize the welding workload on the side of the cladding. No matter whether the cladding is on the inside or outside, the base course shall be welded first. When the cladding is on the inside, the root of the base course shall be cleaned from the inside before welding the cladding. When the cladding is located on the outside, the rear weld bead of the base shall be polished. When welding the cladding, weld the transition layer first and then the cladding.
3. Filler metal selection
In most cases, appropriate intermediate filler metal is selected as the transition layer of steel, so as to control the iron content of the final weld bead of the clad metal, avoid embrittlement and cracks in the weld bead at the clad and base layer, and ensure the corrosion resistance, wear resistance and other special properties of the clad weld bead.
4. Welding sequence and welding material selection
Generally, the base course shall be welded first, and the weld of the first base course (carbon steel, low alloy steel) shall not be penetrated into the clad metal to prevent embrittlement or crack of the weld metal.
When welding (surfacing) one side of the cladding, the influence of dilution must be considered. Therefore, when welding the cladding of clad plate, appropriate filler metal should be selected, first surfacing one or more transition layers, and then welding the cladding. The filler metal of the transition layer must be able to allow the dilution of the base steel.
The root can be cleaned by carbon arc gouging, chipping or grinding. Before surfacing the transition layer, any residue in the weld root groove must be removed.
To eliminate welding residual stress by post weld heat treatment, the following factors should be considered when selecting heat treatment temperature: the difference of heat treatment specifications between base course and clad course; Influence on the corrosion resistance of the coating; Whether the element diffusion at the interface between the base layer and the composite layer will produce brittle phase, resulting in the deterioration of the properties of the steel plate; Due to the difference in physical properties between the base course and the composite layer, stress corrosion cracking occurs in the composite layer.
5. Post weld heat treatment
Jinan composite board factory reminds that stress relief heat treatment can be carried out after welding the base course, then welding the transition layer, and then welding the cladding. Take the lower limit of heat treatment temperature and extend the holding time. Come to our website for more relevant content http://www.jnjgcg.com Consult.