309 309S Stainless Steel.pdf

309-309S-Stainless-Steel.pdf

309 stainless steel is a typical austenitic stainless steel with "medium and high temperature oxidation resistance". With its high chromium and nickel content, it performs well in the range of 650~980℃. It is suitable for scenarios that need to resist high temperature oxidation but do not require extreme temperature resistance (such as 310). Its disadvantages include limited corrosion resistance in chloride environments, easy sensitization of standard types (309S is required), and higher cost than 304. Common standard specifications include ASTM A240 and GB/T 24511. When purchasing, the carbon content (309 or 309S) and heat treatment state (solution annealing) must be specified to match the working conditions.

 

Comparison with Other Stainless Steels

Grade	Core Difference	High-Temperature Performance	Key Advantages	Temperature Range
304	Cr 18%, Ni 8%	Long-term service temperature ≤650℃, weaker resistance to high-temperature oxidation	High cost-effectiveness, excellent corrosion resistance at room temperature	Room temperature ~ 650℃
309	Cr 22%, Ni 13%	Long-term service temperature ≤980℃, significantly improved oxidation resistance	Suitable for medium-to-high temperature oxidation environments (e.g., furnace components)	Room temperature ~ 980℃
310	Cr 25%, Ni 20%	Long-term service temperature ≤1150℃, resistance to high-temperature sulfidation/oxidation	Ideal for extreme high temperatures (e.g., smelting furnaces, petrochemical high-temperature furnaces)	Room temperature ~ 1150℃
430	Ferritic (nickel-free)	Poor high-temperature strength, prone to embrittlement	Low cost, suitable for non-corrosive environments at room temperature