What color is the stainless steel weld

Compared with ordinary carbon steel, the welding process of stainless steel and the technical requirements for welders should be strict. What color is the best weld. Here are my personal views and views to share with you. It is verified by welding experiments (manual welding, automatic welding, argon arc welding) that the welds can be divided into:

• 1. Silver white
• 2. Golden
• 3. Five colors (Golden + blue)
• 4. Blue
• 5. Dark blue
• 6. Grayish black (with luster)
• 7. Dead black ash.

Silver white is the best. The multicolored welds have partially produced intergranular corrosion and chromium deficiency, that is, the so-called chromium carbide, which makes stainless steel lose the function of rust resistance and corrosion resistance. The color after blue and dark blue is impossible for welding quality.

The quality of weld color is inseparable from the welding process parameters and the technical level of welders. The main problems are:

• 1. Cleanliness of groove before welding
• 2. Purity and flow of shielding gas
• 3. Welding current
• 4. Quality of welding materials
• 5. Number of passes and layers of welds
• 6. Welding speed
• 7. Control of interlayer temperature
• 8. Control of heat input

When the welding process conditions are met, the weld should be silver white, and the physical and chemical values of the weld are also the best. For automatic submerged arc welding equipment, the welding parameters and heat input shall be strictly controlled. In fact, the thickness of each weldment is different, so that the welding current, voltage, welding speed and wire feeding speed can be reasonably matched. In fact, welding is like acting. The leading actor and supporting actor must reach 100% tacit understanding in order to give full play to the highest effect. For example, for workpieces with the same material and different wall thickness, the welding parameters must be different. If the parameters are too large, intergranular corrosion will occur, resulting in poor chromium, serious cracks and ugly color. According to experience, the above silver white and yellow quality are OK, and silver white is the best. The multicolored welds have partially produced intergranular corrosion and chromium deficiency, that is, the so-called chromium carbide, which makes stainless steel lose the function of rust resistance and corrosion resistance. The color after blue and dark blue is impossible for welding quality.
In practical work, the welding process parameters cannot be rigidly set. Due to the different ambient temperature, weldment thickness, weldment size and welding speed, the applicable parameters are also different. When welding large weldments with large wall thickness, of course, the current should be larger. If necessary, multi-layer and multi pass welding should be adopted, and the interlayer temperature should be controlled. Otherwise, the appearance quality of the weld may be very beautiful and the interior may not meet the real welding quality requirements. When multi-layer and multi pass welding is adopted, the weld bead of the lower layer can be welded after the weld of the previous layer is cooled, so the effect will be better.

During automatic welding, the welding speed and wire feeding speed must also match the corresponding current and voltage. For the same weldment, in order to achieve the best weld effect, if the welding speed changes, it is bound to change the current and voltage or the speed of wire feeder. The faster the welding speed, the greater the voltage, and the faster the wire feeding speed. However, considering the metal melting and welding quality, the best welding speed, current, voltage and heat input should be selected to ensure the weld quality.

Source: China Flanges Manufacturer – Yaang Pipe Industry (www.epowermetals.com)

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

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