Mild Steel Temp Limit?

[GlassMann]

I'm a glass artist working on a new project. I'm planning to wrap/thread molten glass around a rotating steel frame. I'm wondering how much heat the steel (common black plumbing pipe) can withstand before "fire scaling" will become a problem. I plan to coat the frame with a graphite spray to act as a release, perhaps it will also protect from the oxidation too? I think 1200f will be hot enough for the process. I'll be firing with propane.

Any ideas or advice will be appreciated.

Glenn

 

[Ron]

Glen...the transition temperature for mild steel is about 1200F, so if you run the temp that high you will risk changing the phase of the steel. Some micro-granular change will take place even below this temperature (you'll anneal the steel...but if strength or hardness are not issues, then no big deal).

As for the flaking, almost any repetitive temperature above a few hundred degrees will cause enhanced surface corrosion. Your best bet is to clean and coat each time.

Another possibility is to ceramic coat the steel or use a ceramic rod in place of the steel.

 

[GlassMann]

Thanks Ron,
I'd planned on coating the steel with a graphite mold coating. Maybe that will help? I'll sand blast the form and recoat before each firing. If that doesn't work I guess I'll switch to stainless.

Glenn

 

[boo1]

Why not use a heat resistant alloy?

 

[GlassMann]

boo1,
I just started using the black plumbing pipe because it was readily available and cheap. What are the names/numbers for some common heat resistant alloys?

Thanks,
Glenn