Compared with ordinary carbon steel, the welding process of stainless steel and the technical requirements for welders are stricter, and the color of the weld seam is the best. The following describes my personal views and opinions to share with you. Through the welding experiment verification (manual welding, automatic welding, argon arc welding), the weld colors can be divided into:
1. silver white
3. Five colors (golden + blue)
5. dark blue
6. Gray black (with gloss)
7. Dead black ash.
The quality of the weld seam is inseparable from the welding process parameters and the technical level of the welder. The main problems are:
1. The cleanliness of the groove before welding
2. Purity and flow of shielding gas
3. The size of the welding current
4. Quality of welding consumables
5. The number of passes and layers of welds
6. Welding speed
7. Interlayer temperature control
8. Control of heat input
When the welding process conditions are all satisfied, the weld seam should be silvery white, and the physical and chemical values of the weld seam are also the best. For submerged arc welding automatic welding equipment, welding parameters and heat input should be strictly controlled. In fact, the thickness of each weldment is different so that the welding current and voltage, welding speed and wire feeding speed are reasonably matched. In fact, welding is like acting. The leading role and supporting actors must reach a 100% tacit understanding in order to achieve the highest effect. For example, workpieces with the same material and different wall thickness must have different welding parameters. If the parameters are too large, intergranular corrosion will inevitably occur, resulting in poor chromium. In severe cases, cracks will also occur, and the color will also be ugly. According to experience: the quality of the above silver white and yellow is acceptable, silver white is the best, and the five-color welds have partially produced intergranular corrosion and poor chromium, which is the so-called chromium carbide, which makes stainless steel lose its rust resistance and corrosion resistance. Function. Colors beyond blue and dark blue have nothing to do with welding quality.
In actual work, the welding process parameters cannot be rigidly set. Due to the difference in ambient temperature, thickness and size of the weldment, and welding speed, the applicable parameters are also different. When welding large weldments with large wall thicknesses, of course, the current should be higher. If necessary, multi-layer multi-pass welding should be used and the temperature between layers should be controlled. Otherwise, the appearance quality of the weld may be very beautiful, and the real welding quality cannot be achieved inside. Require. When multi-layer multi-pass welding is used, the welding seam of the front layer can be cooled before the welding of the lower layer of the welding seam, so that 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, to achieve the best weld seam effect, if the welding speed changes, the current and voltage or the speed of the wire feeder must be changed. The faster the welding speed, the greater the voltage, and the faster the wire feeding speed, but considering the melting of metal and welding quality, an optimal welding speed, optimal current, voltage and optimal heat input should be selected to ensure the quality of the weld.
When using argon arc welding, the following points should be paid attention to:
1. The cleaning before welding must be cleaned in strict accordance with the welding process regulations
2. Argon gas must meet the requirements for welding stainless steel
3. Appropriately increase the diameter of the nozzle to ensure the protection effect
4. Fast welding with small current short arc crank
5. After receiving the arc, wait for the molten pool to cool completely before removing the welding torch
6. Strictly control the heat input. Then, the working environment is also a very important link. The wind and dust in the welding environment, the cleanliness of the weldment surface, the technical level of the welder, and the quality of the welding wire will all affect the quality of the weld.