3J21
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3J21
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- Product Description
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- Commodity name: 3J21
3J21 is a high-performance elastic alloy with the combined properties of non-magnetism, corrosion resistance, and high elasticity. It is widely used in fields such as precision instruments and aerospace.
Product Description
3J21 is a high-performance elastic alloy with the combined characteristics of non-magnetism, corrosion resistance, and high elasticity. It is widely used in precision instruments, aerospace, and other fields. Its main characteristics and parameters are as follows:
Core Attributes
Classification and Composition
Type: Cobalt-based or iron-nickel-chromium-based precipitation-hardening elastic alloy, conforming to YB/T 5253-2011 (replacing the 1993 version).
Composition (mass percentage)
Element Co Cr Ni C 3J21 39.0–41.0% (provides high-temperature stability and non-magnetism) 19.0–21.0% (enhanced corrosion resistance) 14.0–16.0%, Molybdenum (Mo): 6.5–7.5% (enhanced pitting corrosion resistance) 0.07–0.12%, Impurities (P/S) ≤0.010% Physical and Mechanical Properties
Elastic Properties Elastic modulus 196000–215500 MPa, Shear modulus 73500–83500 MPa Strength Tensile strength of cold-rolled strip 1175–1765 MPa, Elongation 3–5% Non-magnetic Magnetic susceptibility ≤1.005 (stable in strong magnetic fields) Corrosion Resistance Resistant to seawater, acids, alkalis, and salt spray corrosion; superior to ordinary stainless steel Density 8.4 g/cm³, Resistivity 0.92 μΩ·m High-Temperature Stability
● Long-term operating temperature ≤400℃, short-term tolerance 800–1000℃ (such as aircraft engine components);
● Elastic recovery rate >95% at high temperatures (10,000-hour test).
Key Processes
Heat Treatment Process
● Solution treatment: 1000–1050℃ for 1 hour + water cooling, to eliminate stress and homogenize the structure;
● Aging strengthening: 400–550℃ for 4–6 hours + air cooling, precipitation of γ’ phase to increase strength (tensile strength can reach over 1100 MPa);
● Taboo: Avoid aging at >450℃ (reduction in plasticity) or repeated solution treatment (abnormal grain growth).
Processing Technology
● Mainly cold-rolled strip/cold-drawn wire, thickness 0.08–0.3mm (suitable for precision components);
● Stress relief annealing at 250–300℃ is required after cold working to ensure dimensional accuracy.
Typical Applications
Field Component Examples Performance Advantages Aerospace Engine blades, turbine disks Resistant to 950℃ high temperature + creep resistance Precision Instruments Sensor springs, hairsprings High elasticity + low hysteresis Medical Devices Elastic components of surgical instruments Biocompatibility + corrosion resistance Automotive Industry High-load shock absorption springs Fatigue life >10⁶ cycles Precautions
● Material selection pitfalls: Ignoring the composition ratio (e.g., Co/Ni deviation reduces high-temperature properties) or microstructure requirements;
● Standard compliance: Must meet ASTM/GB mechanical performance indicators (e.g., tensile strength ≥850 MPa).
● 3J21, through precise composition design and strict heat treatment, has become the preferred material for high-stress, non-magnetic, and corrosive environments, especially irreplaceable in dynamic load scenarios.
The company currently owns production equipment such as vacuum melting, electroslag remelting, forging and hot rolling (outsourced), solution treatment, machining, cold drawing, cold rolling (outsourced), and polishing. Our own laboratory can complete the testing of alloy chemical composition, mechanical properties, and flaw detection.
We can independently produce high-performance alloy materials such as nickel-based superalloys, cobalt-based superalloys, precision alloys, and special stainless steels. Products: forgings, billets, coils, bars, slabs/sheets, etc.
High-temperature alloy cobalt-based GH605/Co-50, etc. Iron-based GH1035/GH696, etc. Nickel-based GH901/GH3030/GH3044/GH4033/GH80A/GH90, etc. Corrosion-resistant alloys Inconel600/625/718/X-750/C276, etc. Expansion/precision alloys 4J29/32/33/36, etc.
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