2Cr13 stainless steel is a martensitic stainless steel with low carbon content, belonging to the Cr13 series. It is widely used in industrial and daily applications due to its moderate corrosion resistance, good toughness, and processability. Below is a detailed introduction:
1. Chemical Composition
The main chemical components (by weight percentage) of 2Cr13 are as follows:
Chromium (Cr): 12.00% – 14.00% (the core element for corrosion resistance, forming a dense chromium oxide passivation film on the surface to prevent further oxidation)
Carbon (C): 0.16% – 0.25% (lower carbon content compared to 3Cr13 and 4Cr13, which is beneficial for improving toughness)
Silicon (Si): ≤0.60%
Manganese (Mn): ≤0.80%
Phosphorus (P): ≤0.035% (controlled to avoid brittleness)
Sulfur (S): ≤0.030% (similarly restricted to ensure material toughness)
Iron (Fe): The remaining balance
2. Mechanical Properties
Mechanical properties are significantly affected by heat treatment. Typical values are as follows:
Property Annealed State Quenched & Tempered State
Tensile strength ≥520 MPa ≥850 MPa
Yield strength ≥300 MPa ≥600 MPa
Elongation (in 50mm) ≥22% ≥16%
Hardness ≤200 HB (Rockwell B ≤93) 30 – 38 HRC (varies with tempering)
3. Physical Properties
Density: Approximately 7.75 g/cm³
Melting point: 1450 – 1510°C
Thermal conductivity: About 25 W/(m·K) at room temperature
Coefficient of thermal expansion: ~10.2 × 10⁻⁶/°C (within 20 – 100°C)
Magnetic: Yes (due to its martensitic crystal structure)
4. Key Characteristics
Good Toughness: Compared to higher-carbon Cr13 steels (such as 3Cr13 and 4Cr13), 2Cr13 has lower carbon content, resulting in better toughness and impact resistance. This makes it suitable for parts that need to withstand certain mechanical shocks.
Moderate Corrosion Resistance: The 12% – 14% chromium content enables it to form a passivation film, providing resistance to atmospheric corrosion, fresh water, and weak corrosive environments (e.g., weak acids, alkalis). However, its corrosion resistance is lower than that of austenitic stainless steels (like 304) and is not suitable for strong corrosive environments (e.g., seawater, high-chloride solutions).
Good Processability:
In the annealed state, it has excellent machinability, making it easy to perform turning, milling, drilling, and other processing operations.
It can be welded, but post-weld heat treatment is usually required to reduce brittleness and avoid cracking.
Adjustable Hardness via Heat Treatment: Through quenching and tempering, its hardness can be adjusted. For example, low-temperature tempering (200 – 300°C) can improve hardness, while medium-temperature tempering (400 – 500°C) can balance hardness and toughness.
5. Heat Treatment Processes
Annealing: Heat to 800 – 900°C, hold for a certain period (usually 2 – 4 hours), then cool slowly with the furnace. This process softens the material, eliminates internal stress, and improves machinability.
Quenching: Heat to 1050 – 1100°C (to achieve complete austenitization), then quench in water or oil. This converts the structure to martensite, significantly increasing hardness.
Tempering: Reheat the quenched steel to 200 – 650°C, hold for a period, then cool. This process reduces brittleness and adjusts the hardness and toughness to meet application requirements.
6. Typical Applications
Due to its balanced performance, 2Cr13 is widely used in the following fields:
Mechanical Components: Shafts, valves, pump parts, bolts, and nuts (requiring moderate strength, toughness, and corrosion resistance).
Kitchen Utensils: Some low-cost kitchen knives, scissors, and cooking utensils (suitable for dry or low-humidity environments).
Medical Devices: Low-stress medical instruments (e.g., some surgical tools) that need to be sterilized regularly.
Hardware Products: Faucet components, door hinges, and other daily hardware (balancing durability and cost).
Automotive and Machinery Parts: Such as engine valves, hydraulic components, etc.
7. Limitations
Limited Corrosion Resistance: Not suitable for long-term use in strong corrosive environments, as it may rust or suffer pitting corrosion.
Lower Hardness Compared to High-Carbon Cr13 Steels: After heat treatment, its maximum hardness is lower than that of 3Cr13 and 4Cr13, so it is not suitable for parts requiring high wear resistance (e.g., high-speed cutting tools).
Sensitivity to High Temperature: Long-term use at temperatures above 300°C may cause a decrease in mechanical properties and corrosion resistance.
In summary, 2Cr13 stainless steel is a cost-effective martensitic stainless steel, mainly valued for its good toughness, moderate corrosion resistance, and processability. It is an ideal choice for applications that do not require extremely high hardness but have certain requirements for toughness and corrosion resistance.