We are using austenistic steel rated at 1400 F maximum service temperature. However, the main limiter here would be the rigidity of your pipe wall.
A/B create a massive amount of vacuum when accelerating the mass flow, while generating a lot of radiant heat. The risk of pipe collapsing is a very high with thin walled non ribbed ducts.
A/B ducts are usually ribbed on full size aircraft for this reason.
I would seriously consider a ceramic coated carbon/ BMI compposite duct in this application.
However, budget might be a concern, as these pre-preg need autoclave curing at 700 F, then post curing at 1500 F.
We mostly make these for military/ rocket applications...