In the vast world of stainless steel materials, the 300 series and 400 series stainless steel stand out with their unique composition, properties, and application fields among many metal materials. Although they are both important members of the stainless steel family, they exhibit significant differences in many aspects, which directly affect their application performance and selection preferences in different scenarios. Next, we will delve into the main differences between these two series of stainless steel.
| Property | 300-Series Stainless Steel | 400-Series Stainless Steel |
| Composition | Chromium + Nickel | Chromium (no/little nickel) |
| Structure | Austenitic | Martensitic/Ferritic |
| Corrosion Resistance | Excellent | Good (but less than 300-series) |
| Strength/Hardness | Lower (can be cold-worked) | Higher (can be heat-treated) |
| Magnetism | Non-magnetic (usually) | Magnetic |
| Cost | Higher | Lower |
| Applications | High-corrosion environments | Strength-focused applications |
Composition
300 Series Stainless Steel
Mainly chromium (16-18%) and nickel (8-10.5%).
Common grades include 304 (18% Cr, 8% Ni) and 316 (16-18% Cr, 10-14% Ni, 2-3% Mo).
Austenitic structure.
400 Series Stainless Steel
Mainly chromium (11.5-18%) with little to no nickel.
Common grades include 410, 420, and 430.
Ferritic or martensitic structure.
Corrosion Resistance
300 Series Stainless Steel
Excellent resistance to general corrosion, pitting, and crevice corrosion.
Good resistance to oxidation at high temperatures.
316 grade offers better resistance to chlorides and acids than 304.
400 Series Stainless Steel
Good resistance to general corrosion, but less resistant to pitting and crevice corrosion than 300 series.
Can be susceptible to stress corrosion cracking in certain environments.
430 grade is less corrosion-resistant than 410 due to lower chromium content.
Mechanical Properties
300 Series Stainless Steel
Higher ductility and toughness.
Lower yield strength and higher tensile strength.
Good formability and weldability.
Cannot be hardened by heat treatment.
400 Series Stainless Steel
Lower ductility and toughness compared to 300 series.
Higher yield strength and lower tensile strength.
Poorer formability and weldability.
Can be hardened by heat treatment.
Magnetic Properties
300 Series Stainless Steel
Non-magnetic or slightly magnetic (depending on composition and processing).
400 Series Stainless Steel
Magnetic.
Heat Treatment
300 Series Stainless Steel
Cannot be hardened by heat treatment.
Solution annealing is used to restore corrosion resistance and ductility after welding or cold working.
400 Series Stainless Steel
Can be hardened by heat treatment.
Annealing is used to soften and improve ductility.
Cost
300 Series Stainless Steel
Generally more expensive due to the higher nickel content.
400 Series Stainless Steel
Typically less expensive than 300 series grades due to the absence of nickel.
Applications
300 Series Stainless Steel
Widely used in various industries due to its excellent corrosion resistance, formability, and weldability.
Common applications include kitchenware, chemical processing equipment, automotive exhaust systems, architectural applications, and medical equipment.
400 Series Stainless Steel
Used in applications where cost, magnetic properties, and moderate corrosion resistance are important.
Common applications include automotive trim, kitchen sinks, architectural panels, and heat exchangers.
Summary
300 series stainless steel offers superior corrosion resistance, formability, and weldability, but is more expensive and less magnetic than 400 series stainless steel.
400 series stainless steel is more cost-effective, magnetic, and has better resistance to chloride stress corrosion cracking, but has lower ductility and toughness, and is less formable and weldable. The choice between 300 and 400 series stainless steel depends on the specific requirements of the application.
For more information about stainless steel products, please contact SSM. We provide product and technical service support.
Stainless Steel Family
Stainless Steel
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