Titanium stringers in 321 tainless steel

[XLR8ing]

What causes titanium stringers in 321 stainless steel?
Is 347 (niobium stabilized) preferable?

Material requirement should contain 0.01%Co & 0.08%Mn ideally.

Any info 321 versus 347 would be appreciated.

 

[EdStainless]

This would be special virgin melt (triple the price) to get Co that low, and I am not sure that you can ever get the Mn that low. This material would be a bitch to hot work.
Why on earth would you want 321 for this? Low carbon will achieve the same thing with a cleaner alloy.

You will always get agglomeration of carbo-nitrides, Ti or Nb it doesn't matter. There will be some banding or stringers.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

 

[metengr]

We have both 321 and 347 stainless steel superheater tubing and I have not observed any stringers in this material. If properly processed the Ti (C,N) should be large precipitates, not bands or stinrgers,

 

[EdStainless]

These are sure not for superheaters.

If there is a large amount of cold work you can break up the agglomerations. Plate of tubing without much cold reduction can show significant banding.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

 

[cloa]

XLR8ing hasn't specified the application at all. If application is important, maybe we should wait for the details.