There will be many cracks on the surface of the wear-resistant composite steel plate. Are the cracks that exist on the overlay steel plate a normal phenomenon?
These cracks look very worrying, and we are afraid that the cracks will expand in the use of it, and even fracture or fall off, thus affecting the wear-resisting effect. The following is a specific analysis of the causes of cracks.
According to the relevant information, we can understand that the production process of wear-resistant composite plate is made by metallurgical overlay welding, the welding current is generally 350~500A, the temperature of the welding arc reaches 1000~1500℃, the instant high temperature makes the welding wire and the mother plate reach the melting point to form a molten pool (the so-called welding channel), and makes the alloy powder added to the molten pool melt to form the overlay layer.
During the surfacing process, the temperature of the mother plate adjacent to the molten pool will reach 600～800℃, or even higher, because the mother plate is generally made of ordinary Q235 low carbon steel, and the wear-resistant layer is high carbon and high chromium, so during the surfacing process, the temperature difference between the various parts of the mother plate is great, producing extremely uneven expansion, shrinkage and deformation, because the mother plate is firmly fastened around by the pressure plate, it cannot be freely deformed, plus the wear-resistant layer is made of a large amount of alloy powder Because the thermal expansion coefficient of the overlay layer and the mother plate are different, the mother plate with good toughness can withstand large thermal deformation, but the ability of the high hardness overlay layer to withstand thermal deformation is almost zero, so it generates great thermal stress inside, and if this stress is not released immediately, it will be easy to break and collapse in the later processing (such as curling). If this stress is not released immediately, problems such as fracture, chipping and wear-resistant layer falling off will easily occur in the process of processing (such as curling).
In the cooling process after the heat deformation, in order to release the welding stress existing in the overlay composite steel plate, many cracks of different sizes will be produced on the surface of the overlay layer perpendicular to the direction of the weld channel, and this crack is the result of stress release, which does not affect the use. Through the analysis we can understand that this kind of worry about the crack is superfluous, wear-resistant composite steel plate using welding technology production, belongs to the metallurgical bonding, bonding performance is very good. The crack will not fall off or fracture in the process of use.