What materials for design of ultra-supercritical boiler tubes?

[btwlzyq]

What materials are generally used for the design of ultra-supercritical high-pressure boiler tubes?
Ultra-Supercritical (USC) high-pressure boiler tubes need to withstand extremely high temperatures and pressures (usually pressures exceeding 27.5 MPa and temperatures reaching 700°C or above), so the material must have excellent high-temperature strength, oxidation resistance, corrosion resistance, and creep resistance.
If the following alloys are used: Inconel steel 617 (UNS N06617), Inconel steel 740/740H, , Alloy 263, Super 304H (UNS S30432), how much high pressure and high temperature can these alloys withstand? Which metal material has the lowest cost? ?

 

[XL83NL]

There’s some literature on this subject. I’m not familiar with these applications though I have done some high temp jobs (with lower pressures) using some of these alloys. From what I’ve read 740/740H is mentioned frequently said to be the next best candidate, along with 617. Their resistance to temperature/pressure is mostly based on the allowable stresses of the applicable design code.