material grade for Atmospheric furnace

don't use the low carbon varieties, you need hot strength

durcan,
Low alloy steel (such as 5Cr-0.5Mo) might be better. What is the reason to use austenitic stainless steel in this application?

there is a low magnetic field, so any magnetic steel / material would effect it.
Mateial has to be non magnetic

Recommended Materials; For Quick Access

1. Low corrosion environment at 500 deg.C :
(1) High strength/creep required: 9Cr-1Mo-V
(2) Medium strength/creep required: 9Cr-1Mo
(3) Low strength/creep required: 5Cr-1/2Mo

2. Medium corrosion environment at 500 deg.C :
(1) High strength/creep required: 347H SS
(2) Medium strength/creep required: 321H/ 304H SS
(3) Low strength/creep required: 316H SS

3. High corrosion environment at 500 deg.C :
(1) High strength/creep required: 310 SS
(2) Medium strength/creep required: 309 SS
(2) Low strength/creep required: 446 SS

* Anticipated Mass of Corrosion: V (V2O5), SO2 (Na2SO4), S, etc.

Thomas

vessel(furnace) design is more than picking a material and if you have specific issues redarding the electrical and or magnetic behavior and its effect on you process then a considerable amount of engineering is required just to establish the basis for design.

500 c (max)and use of austenetic stainless are little enough to define your problem, but if in addition you have a requirement as to non-magnetic, then you need to be specific as to the size of the furnace, the actual field strengths involved and at what location within the chamber, the skin temperatures involved, etc.

Any of the above grades 304L or 316L can be used.at 500C.Also there is another grade commonly used containing 12% Ni and 24% Cr ASTM A 297 Gr HH