The process procedure of spray welding is basically the same as that of spraying. Spray welding has one - step and two - step process.

Attention should be paid before construction:

There is carburized or nitrided layer on the surface of the surface of the surface of the finished workpiece, which must be cleared when pretreatment;

(2) for general carbon steel workpiece preheating temperature 200 ~ 300 degrees and 350 ~ 400 degrees heat resistant austenitic steel. Preheat the flame with neutral or weak carbon flame. In addition, the thickness of spray coating is reduced by about 25% after remelting, which should be taken into account when measuring the thermal state after spray remelting.

one-shot

The one-step method is to spray one section and then melt another section. Can choose medium and small spray welding gun. After the workpiece preheating before spraying 0. 2 mm layer of protection, and the surface densification, prevent oxidation, spraying molten starting at one end, spray from 10 to 30 mm, to cover local heated to melt in order to start again when wet flow (can't) spray welding powder, melt and repeated, until it reaches the thickness, surface reflective "mirror", further extension, reached a surface covering all spray welding layers. If the thickness is insufficient, the thickness can be increased repeatedly. One-step method is suitable for small parts or small area spray welding.

Step two spray welding

The two-step method is to finish the coating layer before remelting it. Both spraying and remelting are used with high-power spray guns, such as sph-e spray and welding guns, to fully melt the alloy powder in the flame and generate plastic deformation of the deposited layer on the surface of the workpiece. Weak carbon flame is used when spraying iron base powder while neutral or weak carbon flame when using spraying welding powder and cobalt base powder.

The thickness of each layer of powder spraying is <0.2mm, and the repeated spraying reaches the remelting thickness. Generally, the remelting can be performed from 0.5-0.6mm. If the spray welding layer is required to be thicker, a remelting can not reach the requirements, several times of spraying and remelting.

Remelting is a key step of the two-step process, which takes place immediately after spraying. With a neutral flame or weak carbonizing flame of high power soft flame spray from about 20 ~ 30 mm, flame and surface Angle 60 ~ 75 degrees, start from about 30 mm from coating, appropriate master remelting speed, heat the coating, until a "mirror" reflective coating for degrees, and then go to the next part of remelting.

During remelting, overmelting (i.e. surface cracking) should be prevented, coating metal flows, or local heating time is too long to oxidize the surface. Multilayer remelting, the previous layer cooled to about 700 degrees, cleared surface slag, make secondary spray welding. Remelting should not exceed 3 times.

Cooling of workpiece. Medium and low carbon steel, low alloy steel workpiece and thin welding layer, simple shape of cast iron parts cool naturally in air. For iron parts with thick welding layer and complex shape, alloy steel parts with high content of manganese, copper and vanadium, and parts with high cold hardness, they should be buried in the pit of lime.

Related link:

http://www.wococarbide.com/Transaction/en_article_info/id/258.html

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