American Welding Society Forum
We are welding V-groove joints in 316L SST. These joints take multiple passes to weld. I am wondering is there any literature or data on maintaining interpass temperatures in this material?
Yes, there is. For maintaining the interpass temperature in stainless steel you should avoid using oxiacetylene or oxigas (such a LPG) flame. Flames contains carbon dioxide and monoxide, and carbon is harmful for stainless steel.
Electrical means of heating, either by induction or resistance, are preferred. There are several firms that manufacture electrical devices for stress relieving of welds (finger elements, as are often called) which can also be used to maintain the interpass temperature.
I don't remember the name of any of those firms in this moment, but perhaps searching into the AWS site you'll be able to find one or two.
They will give you any reasonable information and assistance you need.
Giovanni S. Crisi
Sao Paulo - Brazil
As a general rule, austenitic stainless steels (which includes 316) are not welded with pre-heat. Besides situations where you may be welding at below freezing temperatures, your bigger concern would be to ensure that your interpass temperature is not too high. As a general rule we use 175°C as the maximum interpass temperature.
Maybe you could let us know why you need a pre-heat in your application?
Thanks for the info, I guess I should have phrased that differently. I mean "maximum" interpass temperatures. Since the welding is taking place at room temperature (68 F) I agree that there is no need to pre-heat the material.
I suppose you are talking about "maximum" interpass temperature when talking about 316L. A maximum of 350 F is commonly used to minimize sensitization of weld heat affected zones to increase resistance to stress corrosion cracking. Use of the "L" grade (low carbon) also minimizes potential for sensitization. For some good FREE publications on welding of austenitic stainless steels, go to: www.nidi.org
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