Material group with unique property profile
Copper and copper alloys are characterized by special properties that qualify them as an indispensable group of materials for numerous applications. In particular, the high thermal and electrical conductivity, the high corrosion resistance and the good low-temperature toughness can be named as characteristic properties. Because of copper's tendency to form alloys with many other metallic elements, the range of properties can be varied within wide limits depending on the alloy system.
Joining of copper
Under consideration of the physical, mechano-technological and metallurgical characteristics, copper and copper alloys can be thermally joined with different processes. With regard to the selection of the process parameters relevant for the heat input, special attention must be paid to the high thermal conductivity and thermal expansion in order to provide the necessary energy in a targeted manner on the one hand and to avoid thermally induced distortion and undesired component deformations on the other.
A classification of the weldability can be based on whether the material is a single-phase or multi-phase copper material, a precipitation-hardening alloy or a cold-hardened material. Of particular importance for weldability is the oxygen content in the metal, which can additionally increase due to atmospheric gas absorption during processing. Oxygen can have an embrittling effect in copper materials and, in the presence of hydrogen, lead to so-called "hydrogen sickness".
Joining concepts in innovative future technologies
The joining of copper and copper alloys in the field of electrical contacts has become significantly more important, especially with the rise of electromobility. In the automotive wiring system, for example, multi-material joints (Cu-Al) are also used to reduce costs. Depending on the required joint properties, joining processes with low heat input such as ultrasonic welding, resistance spot welding or friction stir welding are often used.
In technical installations for gas and water supply, TIG orbital welding and TIG circular seam welding are important methods for joining copper pipes. Due to the high quality demands on the conveyed media, one of the aims is to minimize tarnishing inside the pipe by optimizing process control.
For components with larger wall thicknesses and high quality requirements, beam welding processes with high energy density are often used due to the high thermal conductivity of the copper materials, such as laser beam welding under atmospheric pressure or in a vacuum and electron beam welding.
Other potential topics related to copper materials in the context of welding technology are, for example, the investigation of the electrode level in resistance spot welding, wear investigations of current contact tubes or the analysis of the influence of wire electrode copper coating on the process behavior and welding metallurgy.
We are happy to offer you active support for your joining challenges. Contact us if you would like to make use of our process and materials engineering expertise for your applications.