Minimal Thermal Expansion
The property of thermal expansion refers to how much a material expands with heat and contracts when cooling. Minimum thermal expansion in the steel used to construct outdoor stoves is ideal to prevent damage of the firebox and water jacket. When compared to other steel, 409 stainless steel has similar thermal expansion properties of mild steel but much better than 304 stainless steel.
Excellent Corrosion Resistance
Due to the 11% chromium content, 409 stainless steel offers excellent resistance to stress corrosion cracking (SCC) in chloride-containing environments. No 409 stainless steel failures have been reported due to chloride - SCC in wood burning furnaces. 409 stainless steel offers much better corrosion resistance than mild steel.
High Heat Transfer Capabilities
409 stainless steel is similar to mild steel heat transfer capabilities, but transfers heat much better than 304 stainless steel.