General Characteristics

Copper is rarely used in its pure form. Introduction of alloying elements and impurities divides copper into alloys. Such alloys include: copper-nickel alloys, bronze and brass. Brass is an alloy of copper and zinc. In bronze, the main alloying elements are zinc or nickel. Copper-nickel alloys are alloys of copper with iron and nickel or manganese. Presence of additives determines the physical and chemical properties of copper alloys and the choice of welding procedure.

Preparatory operations

During the preparatory stage, a careful cutting and cleaning of the surfaces is carried out immediately before welding. The weld zone and welded edges are cleaned with a metal brush or doctor until shiny, then degreased with gasoline, white spirit or another solvent. Between the surfaces to be welded gap should not be more than 2 mm, to do this, the parts between them squeeze or make tacking.

Difficulties in welding copper

- High coefficient of thermal expansion causes permanent deformations and stresses;

- Good thermal conductivity leads to increased cooling rates of the weld pool. This in turn leads to deterioration of weld quality and grain growth. This phenomenon can be counteracted by welding with high energy input;

- high casting shrinkage of cooling metal entails a significant deformation of the surrounding area and the weld, residual deformations and stresses in cases of rigid fastening of parts;

- high sensitivity of molten copper to hydrogen contributes to the appearance of water bubbles. This can cause multiple cracks and pores. This phenomenon is referred to as hydrogen sickness;

- intense evaporation from the molten metal of zinc can lead to porosity of the weld;

- high fluidity of molten copper leads to additional difficulties in welding (especially in overhead and vertical joints);

- at high temperatures, copper easily oxidizes. This contributes to the formation of refractory oxides.

Upon completion of welding, the seam is first forged and then annealed at 600 to 660 °C in order to obtain a fine grain structure of the seam and to even out the chemical composition.

Welding wire

Before use, it is cleaned by etching with aqueous nitric acid (75 cm³/litre) or a mixture of hydrochloric and sulphuric acids in a 100:1 ratio with a further rinsing in water, then in alkali, and then again in running clean water. After washing, the wire is dried with hot air. For example, copper electrodes are calcined before welding, thus reducing the possibility of hydrogen sickness.

Protective atmosphere

Welding of copper alloys and copper is carried out in protective gas environments, in nitrogen, argon or helium, and their mixtures. The greatest welding efficiency is achieved with nitrogen, which provides a high coefficient of performance of the arc discharge.

Buy, price

Evek GmbH stocks a wide range of high quality non-ferrous products. We supply copper and copper alloy products in standard and non-standard sizes to wholesale and retail. All the lots have the quality certificate on correspondence of standards and technical conditions of exploitation. The certificate indicates the manufacturer, drawing number and name of the parts, alloy grade, the mechanical properties of the parts, chemical composition and the results of additional tests. Implementation of orders - in the shortest possible time. Preferential discounts are offered to wholesale customers.