Welding process used: small specifications can prevent intergranular corrosion, thermal cracks, and deformation, and the welding current is 20% lower than that of low-carbon steel; to ensure stable arc burning, DC reverse connection is used; short arc welding should be slow to fill the arc pit, and the surface in contact with the medium should be welded last; the interlayer temperature should be controlled during multi-layer welding, and forced cooling can be adopted after welding; do not start the arc outside the groove, and the ground wire should be connected well; deformation after welding can only be corrected by cold processing.
1. Argon arc welding
When stainless steel is welded by argon arc welding, due to good protection, alloy elements are not easy to burn, and the transition coefficient is high, the weld is well formed, there is no slag shell, and the surface is smooth, so the welded joint has high heat resistance and good mechanical properties. At present, manual tungsten inert gas welding is widely used in argon arc welding, which is used to weld 0.5~3mm stainless steel sheets. The composition of the welding wire is generally the same as that of the weldment. The shielding gas generally uses industrial pure argon gas. The welding speed should be appropriately faster and lateral swing should be avoided as much as possible. For stainless steel with a thickness greater than 3mm, argon arc welding can be used. The advantages of argon arc welding are high productivity, small heat-affected zone of welds, small deformation of welds, good corrosion resistance, and easy automation.
2. Gas welding
Because gas welding is convenient and flexible, it can weld welds in various spatial positions. For some stainless steel parts such as thin plate structures and thin-walled tubes, gas welding can sometimes be used without corrosion resistance requirements. To prevent overheating, the welding nozzle is generally smaller than when welding low-carbon steel of the same thickness. The gas welding flame should use a neutral flame. The welding wire is selected according to the composition and performance of the weldment. The gas welding powder uses gas 101. It is best to use the left welding method when welding. When welding, the welding torch nozzle, and the weldment are inclined at 40~50°. The flame core should be no less than 2mm from the molten pool. The end of the welding wire is in contact with the molten pool and moves along the weld with the flame. The welding torch does not swing horizontally, the welding speed should be fast, and interruptions should be avoided as much as possible.
3. Submerged arc welding
Submerged arc welding is suitable for welding stainless steel plates with medium thickness or above (6~50mm). Submerged arc welding has high productivity and good weld quality, but it is easy to cause segregation of alloy elements and impurities.
4. Manual welding
Manual welding is a very common and easy-to-use welding method. The length of the arc is adjusted by the human hand, which is determined by the size of the gap between the welding rod and the workpiece. At the same time, when used as an arc carrier, the welding rod is also a weld filler material. This welding method is very simple and can be used to weld almost all materials. For outdoor use, it has good adaptability and can be used even underwater. Most electric welders can TIG weld. In electrode welding, the arc length is determined by the human hand: when you change the gap between the electrode and the workpiece, you also change the length of the arc. In most cases, welding is done with Direct current, the electrode acts as both an arc carrier and a weld filler. The electrode consists of an alloy or non-alloy metal core wire and a welding rod coating. This coating protects the weld from air damage and stabilizes the arc. It also causes the formation of a slag layer, protecting the weld and shaping it. The welding rod can be either a titanium-type welding rod or a sealing type, depending on the thickness and composition of the coating. Titanium-type welding rods are easy to weld, and the weld is flat and beautiful. In addition, the welding slag is easy to remove. If the welding rod is stored for a long time, it must be re-baked because moisture from the air will quickly accumulate in the welding rod.
5. MIG/MAG welding
This is an automatic gas MIG/MAG welding is a shielded arc welding method. In this method, the arc burns between the current carrier wire and the workpiece under the shield of the protective gas. The wire fed by the machine acts as a welding rod and melts under its own arc. Due to the versatility and specificity of MIG/MAG welding, it is still the most widely used welding method in the world. It is used for steel, unalloyed steel, low alloy steel, and high alloy-based materials. This makes it an ideal welding method for production and repair. When welding steel, MAG can meet the requirements of thin gauge steel plates with a thickness of only 0.6 mm. The shielding gas used here is an active gas, such as carbon dioxide. Carbon or mixed gas. The only limitation is that when welding outdoors, the workpiece must be protected from moisture to maintain the effect of the gas.
6. TIG welding
The arc is generated between the refractory tungsten welding wire and the workpiece. The shielding gas used here is pure argon, and the welding wire fed in is not charged. The welding wire can be fed by hand or mechanically. There are also some specific uses that do not require the feeding of welding wire. The material being welded determines whether direct current or alternating current is used. When direct current is used, the tungsten welding wire is set to the negative pole. Because it has a deep penetration ability, it is very suitable for different types of steel, but it has no “cleaning effect” on the weld pool.
Post time: Mar-12-2025