Laminations in SS vs CS

[Mat001]

Ingot casting was prone to produce laminations, however with continuous casting and the advancements in refining there is significant improvement of steel quality.

My question is, are Laminations more commonly expected in carbon steel (A516-70) v/s stainless steel (304SS) ? We have practice of UT testing CS plates for laminations, however SS material is exempt. I am not sure, why we would have that. Most of commercial quality SS have similar sulfur restrictions as CS and due to volume it is more likely that 304 SS may produced by ingot casting than cont.casting. Please share your expertise. Thank you.

 

[EdStainless]

In stainless that is continuous cast laminations would be rare, with a few exceptions.
In stabalized grades (321, 347, 439 and so on) there is a risk for either laminations or clusters of inclusions that are oxidized Ti, Nb, or Zr.
We can find these when we UT 439 tubing (welded from strip).
That said I would UT any plate from ingot cast, and any stabalized grade (especially ferritic).

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P.E. Metallurgy, Plymouth Tube

 

[racookpe1978]

For my own background info then, how are the various stainless "alloys" in the crucible actually mixed to ensure they do "pour" as a uniform mix when you have very high percents of the other metals?

Seems like a stainless alloy would be more likely to separate and form these type of lamination flaws than a very low percent alloy like plain carbon steel. (Once poured and cooling, obviously, the lamiantions would be be caused by the physical processes of grain growth and layering, etc.)

 

[EdStainless]

The laminations are tied to inclusions, not just composition variations.
They pour 100T of stainless in less than 30 min, not enough time for it to separate much.
I have seen samples off of each of 10 slabs out of the caster and you cant tell them apart.
In con-cast the ladle is bottom pour, and the tundish is fairly large, so there is very little turbulence and the metal stays very clean.

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P.E. Metallurgy, Plymouth Tube

 

[Mat001]

Thank you Ed, Racookpe1978. Appreciate your input.