Product Description
4J28 (also known as FR-28, Carpenter27, Croloy27, VaCovito25, 26Cr-Fe) is a precision-controlled expansion alloy designed for applications requiring low thermal expansion, high corrosion resistance, and excellent mechanical stability. It is commonly used in electronic sealing, aerospace, instrumentation, and precision industrial applications where stable performance under temperature variations is crucial.
Specifications:
| Parameter |
Details |
| Alloy Name |
4J28 (FR-28 / Carpenter27 / Croloy27 / VaCovito25) |
| Material Type |
Precision Low-Expansion Alloy Steel |
| Product Form |
Bar / Rod (Round, Square, Rectangular) |
| Chemical Composition |
Fe (Balance), Cr (≈26-28%), Ni (≤3%), Other Elements |
| Standards |
ASTM F30, DIN 17745, GB/T 15002 |
| Diameter (Rod) |
2 mm - 100 mm (customizable) |
| Length |
Up to 6 meters (custom lengths available) |
| Density |
7.8 g/cm³ |
| Tensile Strength |
≥ 650 MPa |
| Yield Strength |
≥ 400 MPa |
| Elongation |
≥ 20% |
| Hardness |
75-85 HRB |
| Thermal Expansion Coefficient |
Low (stable under temperature changes) |
| Corrosion Resistance |
Excellent resistance to oxidation and chemical exposure |
| Magnetic Properties |
Controlled magnetic permeability |
| Machinability |
Good (Supports CNC machining, turning, and grinding) |
| Weldability |
Excellent (Suitable for laser, TIG, and MIG welding) |
Key Features:
Low Thermal Expansion:
- Maintains dimensional stability under fluctuating temperatures.
- Ideal for precision instruments and electronic sealing applications.
High Corrosion & Oxidation Resistance:
- Performs well in harsh industrial environments and chemical exposure.
- Used in vacuum-sealed components and electronic enclosures.
Superior Mechanical Strength:
- High tensile and yield strength, making it suitable for high-load conditions.
- Resistant to thermal fatigue and wear.
Good Electrical & Magnetic Properties:
- Controlled magnetic permeability, suitable for electromagnetic shielding.
- Used in components requiring stable electrical conductivity.
Excellent Workability & Weldability:
- Can be easily machined, cut, and polished.
- Supports TIG, MIG, laser, and resistance welding.
Common Applications:
Electronics & Telecommunications:
- Used in electronic packaging, vacuum tubes, and RF shielding.
- Applied in connectors and precision resistor components.
Aerospace & Defense:
- Precision parts for aircraft, satellites, and missile guidance systems.
- Components requiring thermal expansion control in extreme conditions.
Industrial & Automotive:
- Sealing materials in high-performance engines and turbine housings.
- Temperature-resistant structures in automotive sensors and exhaust systems.
Scientific & Medical Equipment:
- Laboratory precision instruments and optical measuring devices.
- Diagnostic and analytical instruments requiring dimensional stability.
Available Sizes & Customization:
| Diameter (Rod/Bar) |
Length |
Surface Finish |
Processing Options |
| 2mm - 100mm |
Up to 6m |
Cold Rolled, Annealed, Polished |
Cutting, Grinding, CNC Machining |
Custom sizes and specifications available upon request to meet specific industrial applications.
Shandong Titanium Nickel Special Steel Co., Ltd., registered funds (one thousand yuan for 10,000 yuan), the company is mainly committed to high -tech enterprises that are integrated with special alloy materials, specializing in the research and sales of special alloys such as nickel -based and iron -based. Products include corrosion-resistant alloys, superalloys, precision alloys, Hastelloy, Monel, INCONEL, INCOLOY, copper-nickel alloys, titanium and titanium alloys, zirconium and zirconium alloys, nickel and nickel-based alloys, nickel-cobalt-based heat-resistant alloys , Hafnium alloy, etc., more than 60 kinds of alloy materials such as special stainless steel. On the basis of stabilizing the quality of the original products, according to the market demand, it solves the quality problems existing in the traditional metallurgical process, and ensures the low miscellaneous and low deflection of the alloy material products, which has won an excellent reputation in the industry.
| Item |
Precision Alloy Bar |
Precision Alloy Tube |
| Material Types |
Nickel-based, iron-nickel-based, cobalt-based alloys |
Nickel-based, iron-nickel-based, cobalt-based alloys |
| Common Materials |
1J50, 1J79, 4J36 (Invar alloy), GH4169 |
1J50, 1J79, 4J36, GH4169, Monel 400 |
| Performance Features |
- High strength and toughness
- Excellent corrosion resistance
- Superior magnetic properties |
- Precision dimensional control
- High corrosion resistance
- Excellent thermal stability |
| Size Range |
Diameter: 2mm - 200mm, customizable length |
Outer diameter: 0.5mm - 100mm, wall thickness: 0.1mm - 10mm |
| Processing Methods |
Hot rolling, cold drawing, precision forging, machining |
Cold drawing, precision welding, cold rolling, hot extrusion |
| Surface Treatment |
Polishing, pickling, oxidation treatment |
Internal and external polishing, pickling, coating treatment |
| Main Applications |
- Manufacturing electronic components (e.g., transformer cores)
- High-temperature, high-pressure equipment parts
- Medical equipment components |
- Precision instrument pipelines
- High-temperature, high-pressure pipelines
- Fluid transfer systems |
Detailed Photos
Key Advantages:
- Controlled Properties: Tailored for specific applications, offering controlled expansion, high strength, or high electrical conductivity.
- Dimensional Stability: Excellent flatness, accuracy, and stability, even under thermal cycling.
- High Durability: Resistant to thermal, mechanical, and magnetic stresses, making them suitable for critical components in sensitive environments.
Factory workshop
Product application
Packaging & Shipping
FAQ
1: What is precision alloy?
Precision alloys refer to special alloys with high purity, uniformity and stability. They are usually used to manufacture parts or components that have extremely strict size, shape and performance requirements. They have special physical properties (such as magnetic, electrical, thermal, etc.) and chemical properties to meet specific engineering requirements.
2: What are the main types of precision alloys?
Precision alloys can be divided into many types according to their different physical properties, mainly including:
Magnetic alloys: Such as soft magnetic alloys and permanent magnetic alloys (hard magnetic alloys).
Elastic alloy: An alloy that can deform reversibly under certain stress or temperature conditions.
Expansion alloy: An alloy with a large linear expansion coefficient within a certain temperature range.
Thermal Bimetal: A composite material composed of two or more metallic materials that exhibit different thermal expansion properties.
Resistive Alloys: Alloys with stable resistivity and constant temperature coefficient of resistance.
Thermoelectric alloy: Alloy with thermoelectric effect.
Hydrogen storage alloy: An alloy with hydrogen storage function.
Shape memory alloy: Alloys with shape memory effect.
Magnetostrictive alloy: A type of metal material with magnetostrictive effect.
3: What are the main application areas of precision alloys?
Precision alloys are widely used in aerospace, automobiles and trains, energy and chemicals, medical equipment, electronics industry, fasteners and other fields. For example, in the aerospace field, precision alloys are used to manufacture aircraft engines, aviation structural parts, missiles, etc.; in the automotive and train field, they are used to manufacture engines, transmission systems, chassis components, tracks, wheels, etc.
4: What is the production process of precision alloy?
The production process of precision alloys includes the selection and pretreatment of alloy raw materials, smelting and casting, heat treatment and processing technology, as well as surface treatment and performance testing. The entire production process requires precise control of each link to ensure that the composition and performance of the alloy meet the requirements.
5: How to detect the quality of precision alloy?
Quality testing of precision alloys is mainly through chemical analysis and physical property testing. Commonly used testing methods include spectral analysis, tensile testing, hardness testing and low-temperature impact testing to ensure that each batch of alloys can meet predetermined technical requirements.
6: What are the significant advantages of precision alloys?
Advantages of precision alloys include:
Has unique physical properties, such as excellent electrical conductivity, thermal conductivity and magnetism.
Excellent mechanical properties, high strength, wear resistance and good elasticity.
Strong corrosion resistance and long service life.
Stable performance in a wide temperature range and wide application.
It has good processing performance and is easy to manufacture precisely.
The ingredients and organization are controllable to meet diverse needs.
7: What kind of performance does precision alloy show in a magnetic field?
Magnetic alloys in precision alloys exhibit excellent magnetic properties in magnetic fields. For example, soft magnetic alloys have high magnetic permeability and low coercivity, are easy to demagnetize, and have low energy loss during cyclic magnetization, making them indispensable materials in electromagnetic equipment.
8. How can I contact you for more information?
You can contact us through the following methods
Online support: Visit our website for live chat
Address: 300 Meters North of Liaoniu Road and Xindong Ring Road, Liaocheng High-Tech Zone, Liaocheng, Shandong, China
We look forward to providing you with high-quality products and services!
If you have any other questions, feel free to contact us, and we will do our best to assist you!
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