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Old 08-08-2022, 08:43 AM
JBFab JBFab is offline
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Join Date: Oct 2006
Location: North Central Wisconsin
Posts: 1,650

Alright, Corten is a brand name for ASTM A588 Weathering steel. A588 is indeed an HSLA grade, but not all HSLA is A588 (or weathering steel for that matter). A588 surface rusts very quickly, but that rust sort of encapsulates the steel beneath it slowing down further rusting. You won't see sheets of rust flaking off of A588. It's commonly used on RR bridges, not just because of the added yield strength over conventional A992, but because they don't have to paint it. Also, if you're going to use A588 for it's weathering properties, you ought to use the welding consumables to weld it as well.
Otherwise you're defeating the purpose. Another misconception out there is that HSLA (including A588) is produced to pass yield/tensile test and NOT to a specific chemistry. That is false - they must pass both.

All that being said, the surround looks great Ted! For the application I don't think anything mentioned is going to last any appreciably amount longer than the other with the exception of inconel or 316 stainless, but in that case I'd bet it would crack due to expansion sooner than anything else - maybe not if it's not too restrained.
I believe the appropriate metaphor here involves a river of excrement and a Native American water vessel without any means of propulsion.
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