Puzzles in welding austenitic stainless steel
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When welding austenitic stainless steel, if the weld is cooled naturally after welding, isn’t there a risk of chromium deficiency? Some engineers say it’s okay to use rapid water cooling, while others say it’s absolutely not allowed. I’m confused :(
During the welding of austenitic stainless steel, air cooling does not result in chromium depletion at the grain boundaries, as the cooling rate during air cooling is relatively fast and the residence time at temperatures between 800–500°C is not long enough to cause such depletion. Generally, manufacturing companies opt for air cooling. Water cooling accelerates the cooling rate, but it is not feasible in some situations.
What was said on the 2nd floor makes sense. When welding austenitic stainless steel, A102 electrodes are commonly used. Firstly, their lower carbon content compared to the base material helps to reduce the tendency for intergranular corrosion. Secondly, elements such as Si and Mo present in these electrodes facilitate the formation of the σ phase, which also helps to decrease the risk of intergranular corrosion. Lastly, the cooling rate is relatively fast. Therefore, chromium depletion generally does not occur between 450–850°C.
Reply to 3# suqianyangkang: 1. This analysis is merely theoretical; in reality, the A102 weld seam is relatively prone to corrosion. 2. You can try using A132 instead of A102 for welding to see how it works. 3. Especially in environments containing S and H elements, at relatively high temperatures.
Reply to 4# ljm1372231: JB/T4809 states that A102 welding electrodes can be used entirely for welding austenitic stainless steels. Weld rod A132 is commonly used for the transition layer when welding austenitic stainless steel to carbon steel. Its price is relatively high (mainly due to the titanium it contains). It is not impossible to use A132 for welding austenitic stainless steel, but it is somewhat wasteful.
I’ve learned a lot; thank you all. Our company also often needs to weld stainless steel. May I ask whether 316L stainless steel also belongs to the austenitic stainless steel series?
I asked the technician, who said that the welding rod mainly used for welding 316L stainless steel is A022; I’m not sure if that’s correct.
Reply to 7# xavier_xasm: 316L is a foreign grade; it is equivalent to 00Cr17Ni14Mo2 in China. It is an austenitic stainless steel, and the appropriate welding rod is A022.
The welding electrodes for 316L stainless steel are mainly A022