316L stainless steel pipe welding precautions 316L stainless steel pipes have poor weldability, martensitic chromium stainless steel tends to be brittle when welded, and ferritic chromium stainless steel is easy to grow under the action of high welding temperature, making the weld more brittle. Although chromium-nickel stainless steel has good weldability, the welding current is large, and problems such as intergranular corrosion of welded joints, weld hot cracks, welding stress and deformation are likely to occur.
1. 316L stainless steel pipe electrodes are usually available in two types: titanium calcium type and low hydrogen type.
The welding current is a DC power supply as much as possible, which is conducive to overcoming the redness and shallowness of the electrode.
Titanium calcium type coated electrodes are not suitable for all-position welding, but only for flat welding and flat angle welding; low hydrogen type coated electrodes can be used for all-position welding.
2. Stainless steel electrodes should be kept dry during use.
In order to prevent cracks, pits, pores and other defects, the titanium calcium type coating is dried at 150-250°C for 1 hour before welding, and dried at 200-300°C for 1 hour at low temperature. – Hydrogen type coating.
Do not repeat drying many times, otherwise it will peel off easily.
3. Clean the welding nozzle and prevent the electrode from degreasing and other dirt, so as not to increase the carbon content of the weld and affect the welding quality.
4. To prevent heat and intergranular corrosion, the welding current should not be too large, generally about 20 lower than the carbon steel electrode, the arc should not be too long, the layer should be cooled quickly, and narrow tunnel welding is appropriate.
5. When guiding the arc, be careful not to cause arc discharge in the non-welding part. Use an arc guide plate of the same material as the weldment to generate the arc.
6. Short arc welding should be used as much as possible, and the arc length is generally 2-3 mm. If the arc is too long, thermal cracks will not be generated.
7. Conveyor rod: Short arc fast welding should be used. Generally, horizontal swing is not allowed. The purpose is to reduce the welding heat and heat affected zone of 304 stainless steel pipe, improve the resistance of the weld to intergranular corrosion, and reduce thermal cracks. 8. The welding of dissimilar steels should be carefully selected to prevent abnormal thermal cracking or high-temperature heat treatment of the welding rod, causing σ phase precipitation and metal embrittlement. Select the reference tube and dissimilar steel electrode selection criteria, and adopt appropriate welding process.

                                                                     
Cherry

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