Quality Parameters of Welding Wire
Filler wire is used in welding in a gas environment that prevents the formation of voids in the weld and oxidation of the metal under the influence of atmospheric oxygen. Shielding gases displace oxygen from the welding point, while contributing to the formation of a smooth weld with a homogeneous chemical structure. Helium, argon, and carbon dioxide, as well as their combinations in various proportions, are used as shielding gas mixtures.
List of Requirements for the External Quality of Welding Wire
To obtain a durable weld of sufficient density, the wire must: have a thickness equal to the thickness of the cuts of the parts being welded; melt evenly throughout its entire thickness without forming spatter or densifications; be clean, with no signs of defects: rust, traces of paint or grease, scale, or other imperfections.
To properly select and buy welding wire, it is worth following the advice of experienced specialists. Additional information about the parameters of the metal alloy is contained in the marking and regulatory documents: state standards or technical specifications for the selected sample of consumables.
Basic Requirements for the Metal Alloy of Welding Wire
Increased rigidity of the weld combined with unfavorable external conditions can cause its rapid destruction. To increase the ductility and durability of the weld, it is recommended to select wire with a chemical composition similar to that of the alloy of the elements or structures being joined. The carbon content is particularly important, as its volume affects the price of welding wire. It is undesirable to choose alloys with a high content of phosphorus and sulfur. These substances negatively affect the quality of welding, contributing to the formation of voids in the weld cavity.
Another mandatory condition is the same melting temperature of the elements being welded and the selected wire. Standards allow the use of wire with a melting temperature lower than that of the alloy being processed. This will prevent burning through the elements being welded and the formation of cracks in the finished structure.
Chemical substances — fluxes — can improve the quality of the weld when working with filler wire. They give the metal additional ductility, making the welding surface smooth and neat.
The following can be used as fluxes: borax; boric acid; silicon-based compounds.
The choice of flux depends on the properties of the alloy of the elements being joined and the requirements for weld quality.
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