The difference between preheating temperature and interlayer temperature control of composite stainl

Controlling the preheating and interlayer temperature of stainless steel composite plates before welding can effectively reduce the probability of crack formation.

If the preheating temperature is too high, it will slow down the cooling rate of the stainless steel composite plate weld, and it will also easily lead to the precipitation of carbides at the grain boundary of the welded joint and the formation of ferrite metallographic structure, thus greatly weakening the impact toughness of the joint. If the preheating temperature is too low, the preheating effect will not be achieved and the formation of cracks cannot be effectively prevented.

What needs to be made clear is that the preheating temperature and interlayer temperature for welding stainless steel composite plates and carbon steel should be controlled within the range of 150-300°C.

Regarding the pre-welding preparations for stainless steel composite panels, mechanical processing methods should be used as much as possible for cutting and beveling of stainless steel composite panels. The cutting surface should be smooth. When cutting with a shear, the cladding should be placed upward. Plasma cutting can also be used, and the cladding should be facing upward during cutting. It is forbidden to let the cutting slag fall on the cladding.

When inspecting the groove processing of stainless steel composite panels, the groove form and size should be specified in the drawing design. For example, if the design is not clearly specified, you can refer to the drawing for other selections. The principle of groove selection is to ensure welding quality with less filler metal, low fusion ratio and easy operation. Bevel processing is generally made by mechanical methods. If plasma cutting, gas cutting and other methods are used to create grooves, the oxide layer on the surface of the composite stainless steel plate must be removed. The processed groove should be visually inspected accordingly, and there should be no cracks or delamination, otherwise it will need to be repaired. Before welding cleaning of stainless steel composite panels, mechanical methods and organic solvents should be used to clean the surface within 20mm of the groove and both sides to remove oil stains, rust, metal shavings, oxide films and other contaminants on the surface. Anti-splash coating should be applied within 100mm from the groove.

The assembly of stainless steel composite panels should be based on the cladding. The offset amount cannot be higher than half of the cladding thickness and cannot be higher than 2mm. When the cladding thickness is different, the offset amount should be taken based on the smaller cladding thickness. . Position welding should be welded to the base metal, and the same welding material used for welding the base metal should be used.