Corrosion Resistance of 439 Stainless Steel

439 has good resistance to oxidation and corrosion, particularly in automotive exhaust environments.

Heat Resistance of 439 Stainless Steel

Resistant to oxidation up to 870°C.

Machinability of 439 Stainless Steel

439 has good machinability, similar to carbon steel.

Welding of 439 Stainless Steel

439 is weldable with all standard methods. Preheating and post-weld heat treatment improve performance.

Hot Working of 439 Stainless Steel

Hot working for 439 stainless steel should be done at 1500 – 2000°F (816 – 1093°C). 

Annealing of 439 Stainless Steel

Annealing for type 439 is performed at 1450 – 1650°F (788 – 899°C) followed by air cooling. This helps in restoring ductility and reducing hardness after cold work.

Cold Working of 439 Stainless Steel

439 stainless steel can be cold-worked but may require more force compared to austenitic grades.

Hardening of 439 Stainless Steel

Type 439 cannot be hardened by heat treatment. It can be slightly hardened through cold working.

Application of 439 Stainless Steel

Used in automotive exhaust systems, residential furnaces, and heat exchangers due to its good corrosion resistance and thermal properties.

439 vs. 430: 
439 has better corrosion resistance, formability, and stress corrosion cracking resistance than 430, suitable for more demanding environments.

439 vs. 304: 
304 performs better in highly corrosive environments, but 439 has advantages in stress corrosion cracking resistance and cost.

439 vs. 409: 
439 has significantly better corrosion and oxidation resistance than 409, making it suitable for higher temperature and more demanding environments.

Composition:

439: 18% chromium, titanium-stabilized, good resistance to stress corrosion cracking.

430: 16-18% chromium, no titanium stabilizer, lower corrosion resistance and stress corrosion cracking resistance.

Corrosion Resistance:

439: Better than 430, especially in mildly corrosive environments.

430: General corrosion resistance, not suitable for harsh corrosive environments.

Formability:

439: More ductile than 430, suitable for roll forming and bending operations.

430: Good formability but tends to harden during forming processes.

Applications:

439: Automotive exhaust systems, tubular manifolds, architectural trim.

430: Appliance trims, automotive trim parts, construction materials.

Composition:

439: 18% chromium, titanium-stabilized, ferritic structure.

304: 18-20% chromium, 8-10.5% nickel, austenitic structure.

Corrosion Resistance:

439: Similar to 304 in some oxidizing environments but not as good as 304 in highly corrosive environments.

304: Superior to 439, especially in acidic and chloride environments.

Resistance to Stress Corrosion Cracking:

439: Better than 304, less susceptible to chloride stress corrosion cracking.

304: More susceptible to chloride stress corrosion cracking.

Applications:

439: Automotive exhaust systems, architectural trim, kitchen equipment.

304: Widely used in various industrial and domestic applications, architectural trim, food processing equipment.

Composition:

439: 18% chromium, titanium-stabilized, ferritic structure.

409: 10.5-11.75% chromium, ferritic structure, low cost.

Corrosion Resistance:

439: Better than 409, especially in mildly corrosive and high-temperature environments.

409: General corrosion resistance, primarily used in mild corrosive environments.

Oxidation Resistance:

439: Superior to 409 at high temperatures, suitable for higher temperature environments.

409: Not as good as 439 in high-temperature oxidation resistance.

Applications:

439: Automotive exhaust systems, tubular manifolds, architectural trim, heat exchangers.

409: Automotive exhaust systems (mainly for mid to low-end vehicles), mufflers, agricultural equipment.