Welcome to Jiangsu DLX alloy Co., Ltd.
Email:sales8@dlx-alloy.com Mobile/Whatsapp:+86 199 0611 9641
Specialized manufacturer of high temperature alloys, precision alloys and Incoloy,over 20 years.
Whatsapp:+86 199 0611 9641
Email:sales8@dlx-alloy.com
Add:NO.32 West Taihu Road, Xinbei District, Changzhou, Jiangsu,China
Precision Alloy Rod
Product Details

The 4J29 precision alloy bar is a high-performance, nickel-iron based alloy designed for critical applications in precision instruments. Known for its excellent dimensional stability, this alloy is widely used in industries where performance and reliability are paramount. With a low coefficient of thermal expansion and superior mechanical properties, 4J29 alloy bars are engineered to maintain high precision under varying temperature conditions, making them a preferred choice for a range of high-tech industries.
Parameter | Kovar 4J29 | Alloy 42 (4J42) | 4J49 Fe-Ni-Cr |
|---|---|---|---|
Composition | 29% Ni, 17% Co, 54% Fe | 42% Ni, 58% Fe | 42% Ni, 5% Cr, 53% Fe |
CTE (ppm/°C, 20-400°C) | ~5.0 | ~4.0–4.7 (20-300°C) | ~5.5 |
Temperature Range | -50°C to 400°C | -40°C to 300°C | -50°C to 450°C |
Curie Temperature | ~435°C | ~370°C | ~390°C |
Yield Strength (MPa) | ~345 | ~310 | ~345 |
Tensile Strength (MPa) | ~520 | ~520 | ~550 |
Density (g/cm³) | 8.36 | 8.12 | 8.20 |
Applications | Vacuum tubes, microwave components | Semiconductor lead frames, seals | Semiconductor packaging, vacuum tubes |
Oxidation Resistance | Excellent | Good | Excellent |
Low Coefficient of Thermal Expansion: One of the most notable features of 4J29 precision alloy bars is their exceptionally low coefficient of thermal expansion (CTE). This makes them ideal for applications that require dimensional stability over a broad temperature range.
High Strength and Toughness: Despite being lightweight, 4J29 alloy offers excellent mechanical strength and toughness, making it resistant to wear and tear in demanding environments.
Corrosion Resistance: The alloy's unique composition helps it resist oxidation and corrosion, which is crucial for applications exposed to harsh environments.
Thermal Conductivity: 4J29 exhibits excellent thermal conductivity, allowing it to efficiently manage heat during operation, which is especially beneficial for high-precision instruments.


The 4J29 precision alloy bar is used across several high-tech industries, particularly where dimensional accuracy and material stability are crucial. Key application fields include:
Electronics Industry: 4J29 is commonly used in glass-to-metal seals for vacuum tubes, sensors, and other electronic devices. Its low thermal expansion ensures reliable performance in these components, even under rapid temperature changes.
Aerospace: This alloy is indispensable in aerospace applications, where precision instruments must perform reliably in extreme conditions. 4J29 is used for parts that need to withstand mechanical stress and temperature fluctuations while maintaining alignment.
Optical Industry: In optical systems, maintaining precise alignment of components is essential for optimal performance. 4J29 alloy bars are used in the manufacture of optical components that require high thermal stability and mechanical strength.
Precision Instrumentation: Due to its reliability, 4J29 is ideal for manufacturing precision instruments in both laboratory and industrial settings, where exact measurements and performance are critical.

The production of 4J29 precision alloy bars involves a rigorous process that ensures consistency in quality and performance:
Material Sourcing: High-purity nickel and iron are sourced to create the base alloy with optimal properties for various applications.
Melting and Alloying: The materials are melted at controlled temperatures to form a homogeneous alloy. The precise ratio of nickel and iron ensures the desired properties, including low CTE and high strength.
Hot and Cold Rolling: The alloy is processed through hot and cold rolling techniques to achieve the necessary dimensions and surface finish for the final product.
Heat Treatment: The alloy undergoes heat treatment to enhance its mechanical properties and ensure dimensional stability during operation.
Inspection and Quality Control: Each 4J29 precision alloy bar undergoes extensive testing, including checks for dimensional accuracy, mechanical strength, and thermal expansion characteristics, to ensure it meets industry standards.

Exceptional Dimensional Stability: With its low coefficient of thermal expansion, 4J29 alloy maintains its form and function even when subjected to significant temperature changes.
Enhanced Durability: The alloy's combination of strength and toughness makes it highly durable and resistant to fatigue, ensuring long-term reliability.
Versatility: 4J29 is a versatile material that can be used in various applications across electronics, aerospace, optical systems, and precision instrumentation.
High Precision: As the name suggests, 4J29 is ideal for applications requiring extremely precise measurements and performance, making it indispensable in high-tech industries.



CHANGZHOU DLX ALLOY CO, LTD was established in 2002 and has got ISO9001 International Quality Management System Certificate and SGS Certificate. Our factory is professional in researching and producing special alloy material. From melting, drawing, heat treatment, finishing and testing .We offer nickel based, copper-based, and iron-based alloys, including super alloy, welding materials, anti-corrosion alloy, Precision Alloy , FeCrAl alloy, NiCr alloy, CuNi alloy, thermocouple and etc, in the form of wire, strip, ribbon, bar, tube, plate.



Our 12,000㎡ factory is equipped with complete capabilities for research, production, testing, and packaging. We strictly adhere to ISO 9001 standards in our production processes, with an annual output of 1,200 tons. This ensures that we meet both quantity and quality demands. Furthermore, all products undergo rigorous simulated environment testing including high temperature, high pressure, and corrosion tests before being dispatched, ensuring they meet customer specifications. We also provide chemical analysis reports for every FeCrAl alloy, NiCr alloy, and other products purchased.
For all our clients, we offer timely and multilingual after-sales support and technical consulting, helping you resolve any issues swiftly and efficiently.

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1. What is the best way to contact you?
Our working hours are Monday to Saturday, from 7:30 AM to 5:00 PM (Beijing time, GMT+08:00). During public holidays (May 1-3, October 1-7, and Chinese New Year), please email us for any inquiries, and we will respond as soon as possible.
2. Do you offer free samples?
Yes, we offer free samples for testing purposes. However, the buyer is responsible for the shipping costs.
3. What payment methods do you accept?
We accept various payment methods including T/T, L/C, D/A, D/P, Western Union, MoneyGram, and PayPal for your convenience.
4. What is your lead time for orders?
Typically, the sample lead time is approximately 7 days after payment has been confirmed. For bulk orders, the lead time may vary depending on the quantity and customization required.
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