Welding-copperand copper alloys:SOLUTIONS with Effective, Powerful AdviceWelding-copper, copper welding, welding bronze, nickel-bronze and aluminum bronze alloys, tig Welding-copper, plasma arc Welding Copper, electron beam Welding Copper, copper alloys, brasses, bronzes, welding processes, toxic elements, welding precautions, welding techniques, oxide removal, welding information, welding links, welding tips, improving welding results, safety issues, joining questions needing answers: these are some of the items developed in this Site for the benefit of interested readers. What is in here for me? Ever had occasion of Welding Copper or copper alloys? You certainly know all you need, but maybe some little bit of advice might help. That is why we thought of presenting here a few data which might give an idea of which safety problems could arise in Welding-copper. What benefits can be found here? Essentially a short overview of Welding-copper alloys. However as types and conditions of various copper alloys can be very different, so could be the problems. In order to seek solutions one should focus on a general or on a specific question. Click on the Contact Us Button above-left in the Nav-Bar to send us your Questions and Feedback. Welding copper, including also bronzes and brasses is a most important subject because these materials are outstanding for their elevated electrical and thermal conductivity and for corrosion resistance in certain environments.
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Welding copper properties are somewhat hindered by their high thermal conductivity, which contributes to dissipate rapidly most of the heat that should be used up for local melting, although this property varies widely among the different alloys. As occurring also for other heat treated alloys, Welding copper tends to interfere by lowering the mechanical properties. Occasionally even different metals can be welded to these alloys but special processes or techniques might be required. Copper alloys are usually selected for their high electrical and thermal conductivity, for their pleasant appearance and color with plating and finishing, for their ease of fabrication, forming and machining, for their corrosion resistance, and absence of magnetism. Welding-copper alloys usually include plain copper and beryllium copper, brasses (alloyed with zinc) and bronzes (variously alloyed with tin, nickel, phosphorus, aluminum, silicon) some of them with limited weldability. Warning: As most copper alloys include volatile and toxic elements that are liberated to the atmosphere during Welding-copper, which is not the case with the usual welding of steels, it is imperative to enforce special precautions in order to collect and dispose of noxious fumes, powders and dust and to provide to the welder an effective ventilation system. Elements that markedly hinder Welding copper, and reduce copper alloys weldability are some of the low melting elements like lead, sulfur and tellurium that are sometimes added to render the copper alloys free machinable. Also zinc, which is the main alloying element in brasses, reduces weldability, the more so, the higher is its proportion in the metal. Tin, present in bronzes, is less volatile and less toxic and does not interfere much with Welding-copper. Oxygen, present as oxide in the metal, may leave porosity in the weld and weaken it, unless it is actively removed during Welding-copper by deoxidizing elements like phosphorus, aluminum and silicon or manganese which should be included in the filler metal. In case that adherent oxides of beryllium, aluminum and nickel are present in the joint, they must be removed before Welding-copper by proper cleaning and prevented to form by the presence of argon or of active fluxes, so that they do not interfere with the process. FRICTION WELDING, a solid state process without melting, is famous and almost unique for permitting, like high energy processes in less degree, welds of copper to aluminum or to stainless. Of the RESISTANCE WELDING processes, only spot Welding-copper alloys is widely used: those with the least conductivity are the easiest to weld, those with high conductivity are not suitable, because sufficient heat cannot develop, given the low electrical resistance. As the current employed is higher than that needed for other materials, copper electrodes must have high electrical conductivity and efficient water cooling. GAS WELDING using the oxyacetylene flame is possible for Welding-copper alloys, with the use of suitable fluxes. Tip!: the use of oxyacetylene flame for joining copper would be much easier by adopting, instead of Welding-copper, brazing techniques and proper filler metals, if suitable overlapping joints with needed clearance can be implemented. See the Brazing page. Of the Fusion Arc Welding Processes, (Tig) Gas Tungsten Arc Welding-copper is used for alloys in wrought or cast form and of different hardness values. Preferred conditions are direct current straight polarity (electrode negative) and thoriated tungsten electrodes. Suitable filler metal for Welding-copper, if needed, are described in the following. See:
A Recommended Practice is available: AWS D10.13/D10.13M:2001
GMAW (Gas Metal Arc Welding-copper) (Mig) is preferred when applicable to improve productivity, but there is higher risk of included porosity and lower strength due to the higher heat input. PAW (Plasma Arc Welding) is also used successfully for Welding-copper but limited to a certain thickness because of the high thermal conductivity which interferes with the conditions required for the keyhole technique.
SMAW (Shielded Metal Arc Welding) (also known as stick welding) although feasible for Welding-copper but with larger than usual root opening and wider groove angles and also with higher preheat temperature, is not recommended for most alloys, except for aluminum bronzes where it is applied to a certain extent. In any case welding is limited to the flat position. An Article on selection of Copper Alloy Filler Metal is included in our Practical Welding Letter No. 11 of July 2004. To read the article click on PWL#011. An Article on Welding Copper to Stainless was published in the November 2005 Issue No. 27 of Practical Welding Letter. Click on PWL#027. An Article on Filler Metals for Beryllium Copper was published in the November 2005 Issue No. 27 of Practical Welding Letter. Click on PWL#027. An Article describing processes for joining Silicon Bronze was published in Issue 28 of Practical Welding Letter for December 2005. To read the article (in Section 3) click on PWL#028. An Article on Filler Metals for brazing Copper was published in Issue 34 of Practical Welding Letter for June 2006. To read the article (in Section 4), click on PWL#034. An Article on Joining Copper to Steel was published (3) in Issue 49 of Practical Welding Letter for September 2007. To see the article click on PWL#049. A short note on Welding leaded Brass was published (3) in Issue No. 53
of Practical Welding Letter for January 2008. To receive all the issues of PWL as they are published, click on Subscription. Electron Beam Welding-copper is used for alloys, except for those containing low melting elements like zinc, either to themselves or to other materials (stainless steels, aluminum), but suitable procedures must be implemented especially to limit porosity and to avoid spatter of nondeoxidized copper. Also LASER beam Welding-copper can be used with the usual precautions and protective atmosphere. NEW RESOURCES
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Welding-copper may be difficult. Best use of high power density processes. Know the causes for porosity. Implement provisions against poisoning. See here...
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