316L Tubing-Bad for welding if SULFUR TOO LOW? 7

[cb418]

A client has specified a sulfur range of 0.006 to 0.012% for this material. We would like it to be simply less than 0.012%. Is this reasonable, or will there be problems welding it (primarily orbital automatic GTAW) if it is below 0.006%? I have seen elsewhere on the forum that welding may be adversely affected if there is too much of a difference in sulfur content; would it be a problem welding a tube with 0.012% sulfur to one with 0.001% or so? Thanks.

 

[metengr]

The American Welding Society (AWS) has several papers on the effects of welding low sulfur stainless steels. There are differences, and this needs to be accounted for during production welding. The low sulfur stainless steel appears to exhibit a wider bead profile, resulting in less penetration or wetting with the substrate.

http://www.aws.org/wj/supplement/Pierce/ARTICLE3.pdf

 

[Goahead]

ASM Handbook Vol. 6 page 468
reports that heats of type 304L with
S content 0.001 to 0.003 wt%
may have weld depth to width ratio of only 0.25
whereas the same material but with
S content 0.01 wt%
welded under identical conditions
exhibits a depth to width ratio higher than 0.5

http://www.welding-advisers.com/

 

[EdStainless]

Yes to both of your questions. The S level has a major impact on weld penetration and the smoothness of the weld. Once you get below 0.005% or so things get more difficult.
If you were to weld a piece at 0.006% to a piece at 0.012% the weld would be symmetrical. If you weld a piece of either 0.006 or 0.012 to another piece at 0.002% or less you will not have a symmetrical weld.
Low S material is weldable, it is just more difficult to get nice narrow smooth welds. The thicker the material is the more this becomes an issue.
We don't worry too much about the S level if we are below 0.040" thick. By the time you get to 0.090" thick it very difficult to GTAW in low S material (<0.005%).

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