Stainless steel composite pipes are often used on guardrails and railings. They have good wear resistance and corrosion resistance. For stainless steel composite pipes, their requirements are quite strict, they must be hard and have a glossy surface.
The production process of stainless steel composite pipes is quite rigorous, and the most important step is welding. The temperature, humidity, welding rod, and heat required for welding are different, and production should be carried out according to the purpose to ensure that its performance and characteristics meet the standards. The technical performance requirements for welding stainless steel composite pipes are relatively high, and many skilled workers do not have the ability to weld. The following are the relevant welding steps introduced by the editor for your reference:
1. There are generally two types of stainless steel composite pipe welding rods: titanium calcium type and low hydrogen type. The welding current should be powered by a DC power source as much as possible, which is beneficial for restraining the redness and shallow melting depth of the welding rod. Titanium calcium coated electrodes are not suitable for full position welding and are only suitable for flat welding and fillet welding; Low hydrogen type coated electrodes can be used for full position welding.
2. Stainless steel composite pipe welding rods should be kept dry during use. To avoid defects such as cracks, pits, and pores, the titanium calcium coating is dried at 150-250 ℃ for 1 hour before welding, and the low hydrogen coating is dried at 200-300 ℃ for 1 hour before welding. It is not advisable to repeatedly dry, otherwise the medicine skin may easily fall off.
3. The welding seam should be cleaned and cleaned, and the welding rod should not be contaminated with oil or other dirt to avoid adding carbon content to the weld and affecting the welding quality.
4. To avoid intergranular corrosion caused by heating, the welding current should not be too high. Generally, it should be about 20% lower than carbon steel welding rods. The arc should not be too long, and interlayer cooling should be fast. Narrow pass welding is recommended.
5. Short arc welding should be used as much as possible, with a common arc length of 2-3mm. If the arc is too long, it is prone to thermal cracking.
6. Operation: Short arc rapid welding should be used, and lateral swing is not allowed in general. The goal is to reduce the welding heat and heat affected zone width of stainless steel composite pipes, improve the resistance of welds to intergranular corrosion, and reduce the tendency of hot cracks.
7. The welding strategy of stainless steel composite pipes should be carefully selected with welding rods to avoid improper selection of welding rods, which may cause thermal cracks or high-temperature heat treatment σ Phase precipitation causes metal embrittlement. Refer to the selection specifications for welding rods for stainless steel composite pipes and dissimilar steels, and accept appropriate welding processes.
The welding process and production process of stainless steel composite pipes are quite rigorous, and the technical performance requirements are relatively high. Welding should be carried out according to relevant steps. If problems occur, accidents may occur, especially for bridge guardrails, railings, and facilities used in traffic made of stainless steel composite pipes. Therefore, it is necessary to weld them qualified!