316L stainless steel: an ultra-low carbon steel for 316 stainless steel (06Cr17Ni12Mo2). Ultra-low carbon austenitic stainless steel has good corrosion resistance to various inorganic acids, alkalis and salts (such as sulfite, sulfuric acid, phosphoric acid, acetic acid, formic acid, chlorine salt, halogen, sulfite, etc.). Because of the low carbon content, it has good welding performance and is suitable for multi-layer welding, and generally does not require heat treatment after welding, and there is no tendency of knife edge corrosion after welding. Can be used in the manufacture of synthetic fibers, petrochemical, textile, fertilizer, printing and dyeing and atomic energy and other industrial equipment, such as towers, tanks, containers, pipelines, etc. .
So here comes the question: Does the cooling method have an effect on the 316L stainless steel weld? Which cooling method is the most economical? Test conditions: using electrode arc welding (SMAW), the test use of 316L stainless steel plate thickness 40mm, 55 ° X-shaped equilateral bevel, 1mm blunt edge, welding using 1G flat welding position. Welding using a welding rod diameter of 3.2mm, drying before welding 350 ℃ × 1h, welding current 80 ~ 120A, arc voltage 24 ~ 28V, the maximum heat input of 14.4kJ/cm. welding test, using the same welding parameters, using the following three cooling methods welding 316L stainless steel.
(1) air-cooled
After each weld is completed, the use of compressed air to the weld channel blowing air cooling, compressed air through the air duct in the direction parallel to the weld to cool the weld. The test found that the weld using the air blowing cooling, the effect is not ideal, the weld cooling rate is slow, each weld after the completion of welding, it takes more than 20min, the weld temperature to drop to about 40 ℃ (not hot to the touch).
(2) weld back immersion cooling
First, the welded test plate butt bevel side of the bottoming weld, the back of the root, grinding and cleaning, PT inspection to confirm that there are no defects, the test plate thickness direction half immersed in water (bottoming weld good side immersed in water). Then weld the remaining weld, so that the back of the weld is immersed in water to achieve the purpose of cooling the weld. Due to the poor thermal conductivity of 316L stainless steel, the cooling method of using the back side of the weld immersed in water, the weld cooling rate is also not ideal, after the completion of each weld, it takes more than 15min, the weld temperature to drop to about 40 ℃ (not hot to the touch).
(3) weld water cooling
On the basis of the second cooling method, not only the welded test plate immersed in water, but also each weld after the completion of welding, directly to the surface of the weld water to cool the weld. The test shows that the use of weld water cooling method, the weld cooling speed is significantly accelerated, each weld after the completion of welding, only about 3min water cooling, the weld temperature is reduced to about 40 ℃ (not hot to the touch).
In summary, we can conclude that the use of weld water cooling way to weld 316L stainless steel is feasible to bring benefits to the actual production.