Austenitic stainless steel and martensitic stainless steel are two common types of stainless steel, and they exhibit significant differences in terms of chemical composition, microstructure, mechanical properties, corrosion resistance, and applications. Below are the key distinctions between these two types of stainless steel:
| Propriété | Acier inoxydable austénitique | Acier inoxydable martensitique |
| Structure cristalline | Face-centered cubic (FCC) | Body-centered tetragonal (BCT) |
| Composants principaux | Chromium + Nickel | Chromium + Carbon |
| Magnétisme | Non-magnetic (typically) | Magnetic |
| Strength/Hardness | Lower (can be cold-worked) | Higher (can be heat-treated) |
| Résistance à la corrosion | Excellent | Poorer |
| Formability | Excellent | Pauvre |
| Soudabilité | Excellent | Pauvre |
| Traitement thermique | Cannot be hardened by heat | Can be hardened by heat |
| Applications | High-corrosion environments, high-formability applications | High-strength, high-hardness applications |
Composition chimique
Austenitic Stainless Steel:
Main elements: Chromium (Cr, 16-26%) and Nickel (Ni, 6-22%).
Common grades: 304 (18% Cr, 8% Ni), 316 (with added molybdenum for improved corrosion resistance).
Martensitic Stainless Steel:
Main elements: Chromium (Cr, 11.5-18%) and Carbon (C, 0.1-1.2%), typically very low or no nickel content.
Common grades: 410, 420, 440.
Structure cristalline
Austenitic Stainless Steel:
Crystal structure: Face-centered cubic (FCC).
The austenitic structure is stabilized by adding Nickel (Ni) and Manganese (Mn).
Retains austenitic structure at room temperature, usually non-magnetic (may become slightly magnetic after cold working).
Martensitic Stainless Steel:
Crystal structure: Body-centered tetragonal (BCT).
Transforms from austenite to martensite through rapid cooling (quenching).
Magnetic.
Propriétés mécaniques
Austenitic Stainless Steel:
Lower strength and hardness but high toughness.
Cannot be hardened by heat treatment, but strength can be increased through cold working.
Excellent ductility and formability, easy to weld.
Martensitic Stainless Steel:
Higher strength and hardness but lower toughness.
Can be significantly hardened and strengthened through heat treatment (quenching and tempering).
Poor formability and weldability.
Résistance à la corrosion
Austenitic Stainless Steel:
Excellent corrosion resistance, especially in oxidizing environments (such as acids, salts, and water).
Suitable for food processing, chemical, and marine environments.
Martensitic Stainless Steel:
Poorer corrosion resistance, especially in corrosive environments.
Suitable for environments that require high strength but lower corrosion exposure.
Magnétisme
Austenitic Stainless Steel:
Typically non-magnetic in the annealed state, but may become slightly magnetic after cold working.
Martensitic Stainless Steel:
Magnetic.
Traitement thermique
Austenitic Stainless Steel:
Cannot be hardened by heat treatment, strength can only be improved by cold working.
Martensitic Stainless Steel:
Can be significantly hardened and strengthened through heat treatment (quenching and tempering).
Applications
Austenitic Stainless Steel:
Used in food processing equipment, kitchen utensils, medical devices, chemical equipment, and architectural decoration.
Suitable for applications requiring high corrosion resistance and formability.
Martensitic Stainless Steel:
Used in tools, bearings, valves, pump shafts, and surgical instruments.
Suitable for applications requiring high strength and hardness.
Résumé
Austenitic stainless steel is known for its excellent corrosion resistance, formability, and weldability, making it ideal for applications in food, chemical, and construction industries.
Martensitic stainless steel, on the other hand, is characterized by its high strength, high hardness, and magnetism, making it suitable for applications such as tools, bearings, and surgical instruments.
The choice between these two types of stainless steel depends on the specific application needs. If corrosion resistance and formability are required, austenitic stainless steel is the better choice; if high strength and hardness are needed, martensitic stainless steel is more appropriate.
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