Aging, also known as precipitation hardening or age hardening, is a heat treatment process commonly applied to specific copper alloys to enhance their strength and hardness. While not necessary for all copper products, aging plays a crucial role in improving the mechanical properties of certain alloys, making them suitable for various applications. There is a specific aging treatment method that aims to reduce the residual stress of copper alloy wire. This method applies tensile stress to the copper alloy wire and keeps it at an aging temperature of 300-500℃ for 2-8 hours. This process can make the residual stress diffusion inside the wire tend to be uniform, remove the residual stress inside the material to the maximum extent, and has a significant inhibitory effect on preventing deformation during subsequent processing and use of the wire.
Description
Aging has a very special mechanism, and it has two step processes: solution treatment and precipitation. Solution treatment for copper alloy is to heat the workpiece to a high temperature, typically above 700°C, causing the alloying elements to dissolve into the copper matrix, forming a solid solution. This solution is then rapidly quenched to room temperature, trapping the alloying elements in a supersaturated state, and the supersaturated solid solution is unstable at room temperature. Precipitation is a following process, over time, the alloying elements will precipitate out of the solution as fine, dispersed particles within the copper matrix. This precipitation process is known as aging.
What are the benefits of aging?
The precipitation of these fine particles within the copper matrix significantly strengthens the material through a mechanism called "precipitation hardening." These particles act as obstacles to dislocation movement, hindering the deformation of the crystal structure. As a result, the aged copper alloy shows following benefits:
√ Increased strength and hardness, and it will make copper alloy more resistant to deformation and fracture.
√ Improved wear resistance, the increased hardness also enhances the wear resistance of the aged alloy, making it suitable for applications involving friction and abrasion.
√ Enhanced electrical conductivity, in certain cases, aging can improve the electrical conductivity of copper alloys, particularly those copper alloys containing elements like beryllium, zirconium, chromium, silicon & aluminum, and the copper alloy grades are C17200, C18200, C70600, C17510, C71500, C61300 & C63000.
√ Dimensional stability, and it will reduce its susceptibility to warping or distortion under load or temperature changes.
In summary, aging treatment of copper alloy is an important heat treatment process to improve its hardness and strength by controlling the precipitation of solute elements in the alloy. It is widely used to improve the performance of copper alloy and extend its service life.
Which popular copper alloys require aging process?
There are few popular copper alloys require aging to achieve their optimal properties, and there are two type of aging categories:
√ Precipitation-hardening alloys
Normally, these alloys contain elements like beryllium, chromium, and zirconium as they all have high melting points and high strength as well as hardness. During aging, these elements precipitate out of the solid solution, forming fine particles that hinder dislocation movement and increase the material's strength. Examples of precipitation-hardening copper alloys include:
1. Beryllium copper (C17200, C17300, C17500), it offers high strength, good electrical conductivity, and non-magnetic properties. Used in springs, electrical contacts, and non-sparking tools.
2. Chromium copper (C18200), it has high strength and good electrical conductivity, and these alloys are widely used in spot welding electrodes and electrical contacts.
3. Zirconium copper (C18150), it has high strength and good electrical conductivity, and it's mainly used in electrical contacts and resistance welding electrodes.
4. Nickel-silicon copper (C72200), it is high strength and good corrosion resistance, and it is widely used in springs, electrical contacts, and marine hardware.
√ Age-hardening copper-nickel alloys
These alloys contain significant amounts of nickel (typically 10-30%) and other elements like iron, manganese, and silicon. During aging, these elements form intermetallic precipitates that strengthen the material. The popular copper nickel alloys are:
1. Nickel-copper alloy (C70600), high strength, good corrosion resistance, and good machinability. Widely used in marine hardware, pump shafts, and valve stems.
2. Nickel-copper alloy (C71500), high strength and good corrosion resistance. Widely used in condenser tubes, heat exchanger tubes, and marine hardware.
3. Nickel-copper alloy (C72400), high strength and good electrical conductivity.
Copper Nickel Alloy
What are the applications of aged copper alloys?
The aged copper alloys are widely used in various industries, including:
√ Aerospace, aircraft components, such as landing gear, bushings, and structural parts.
√ Automotive, automotive components like brake lines, electrical connectors, and radiator parts.
√ Marine, copper-nickel alloys products like ship propellers and fittings.
√ Electrical, beryllium-copper alloys products such as electrical contacts and springs.
√ Surgical instruments, aged stainless steel with high strength, corrosion resistance, and good machinability is used in surgical instruments.
√ Implants, aged titanium alloys with excellent biocompatibility, high strength, and corrosion resistance are used in medical implants, such as bone plates and joint replacements.
Aging is a versatile heat treatment process that can significantly enhance the properties of specific copper alloys, making them suitable for a wide range of demanding applications. By carefully considering the alloy composition, aging parameters, and desired properties, Fabmann can optimize the performance of aged copper alloys according to your specific needs, and our metalologists will ensure reliable and high-performance solutions in various industries where strength, wear resistance, electrical conductivity, and corrosion resistance are critical factors.
Which copper alloys usually require age solution?
As you might know that not all copper alloys require aging or precipitation hardening, and this process is typically applied to specific alloys containing elements that can form fine, dispersed precipitates within the copper matrix, leading to significant improvements in strength and hardness. Here are some common copper alloys that benefit from aging:
√ Beryllium-Copper (CuBe), this copper alloy has small percentage of beryllium, and it shows high strength, excellent electrical conductivity, good wear resistance, and non-magnetic properties.
√ Copper-Nickel-Silicon (C70600), this copper alloy has around 10% nickel and 1% silicon, and this composition exhibits high strength, good corrosion resistance, good machinability, and good spring properties. Marine hardware like pump components, valve parts, springs.
√ Aluminum Bronze (C95400), this alloy has around 9-11% aluminum, and aging can generate high strength, good wear resistance, good corrosion resistance, and non-magnetic properties. Gears, bearings, bushings, marine propellers are often made of this alloy.
√ Chromium-Copper (C18200), and it has 0.8-1.2% chromium, this alloy is often used for electrical contacts, spot welding electrodes, resistance welding electrodes.
√ Zirconium-Copper (C15000), and it has 0.15-0.35% zirconium, and this alloy shows high strength, good electrical conductivity, good corrosion resistance, and good high-temperature properties. Electrical contacts, switchgear components, high-temperature springs are often made of this material.
√ Cadmium-Copper (C16200), it has 0.8-1.2% cadmium, it exhibits high strength, good electrical conductivity, good machinability, and good high-temperature properties.
To optimize the aging, there are few factors which you need to always consider:
√ Alloy composition, the type and amount of alloying elements significantly impact the aging behavior of copper alloys. The presence of elements like beryllium, nickel, silicon, aluminum, chromium, and zirconium promotes the formation of precipitates that contribute to strengthening.
√ The temperature and duration, it plays a critical role in determining the size, distribution, and morphology of the precipitates. Higher temperatures and longer times generally lead to larger and coarser precipitates, resulting in increased strength but potentially reduced ductility.
√ Cooling speed, he cooling rate after aging can also influence the final properties of the alloy. Usually, a rapid cooling can preserve a fine precipitate structure, while slower cooling may allow for further precipitate growth.
√ Three types of aging: 1. natural aging involves aging at room temperature, which is a slower process but may be suitable for certain applications where high strength is not the primary concern. 2. Artificial aging, and it involves aging at elevated temperatures, typically between 150°C and 500°C, to accelerate the precipitation process and achieve higher strength levels. 3. Vibration aging, it has gradually come into use since the early 1980s. It achieves the purpose of aging by applying a certain frequency of vibration to the workpiece to release its internal stress. This method does not involve heating and is not as time-consuming as natural aging.
Fabmann has professional material and production engineers who can help you to monitor aging treatment process, and we are committed to deliver high quality copper alloy products which require aging treatment and solid solution treatment.