Electric welding materials mainly refer to electric welding rods. Welding rods are used to conduct welding current, ignite arcs, and melt as filler metal for welds. The basic requirements for welding rods are: to ensure that the chemical composition and metal structure of the weld are similar to the metal of the welded piece, without porosity, slag inclusion, and cracks; it has good welding processability, stable arc, uniform combustion, and less spatter. Appropriate fluidity and good slag removal.
The welding rod is generally composed of a welding core (welding wire) and a coating (ie paint) wrapped on the outside.
1. Welding core
Welding cores are welding wires of different diameters made of different metal materials. According to "GB1300-77 Steel Wire for Welding", there are 44 kinds of welding rod steel wires, which can be divided into three categories: carbon structural steel, alloy structural steel, and stainless steel. The diameter of the electrode is expressed by the diameter of the core. The commonly used electrode diameters are ϕ2mm, ϕ2.5mm, ϕ3.2mm, ϕ4mm, ϕ5mm, etc. Generally, the length of the welding rod is between 250mm and 450mm.
2. Medicated skin
The coating of the welding rod is made by grinding ores, rocks, iron alloys, a small amount of chemical substances, organic matter, etc. into powder, adding a binder to the welding core and drying it. The main function of the coating is to ensure that the weld metal has the required chemical composition and mechanical properties, and to make the electrode have a good welding process performance.
3. Classification and model of welding rod
Electrodes can be divided into carbon steel electrodes, low alloy electrodes, stainless steel electrodes, surfacing electrodes, cast iron electrodes and copper alloy electrodes, nickel and nickel alloy electrodes, aluminum and aluminum alloy electrodes, and special purpose electrodes.
Commonly used electrodes are carbon steel and low-alloy steel electrodes, and their models are compiled in accordance with "GB5117-1995 Carbon Steel Electrodes" and "GB5118-1995 Low Alloy Steel Electrodes". Such as: the meaning of the E4303 model, where the last 3 indicates that the electrode coating is titanium calcium, which can be AC or DC positive and negative; 0 indicates that the electrode is suitable for all-position welding; 43 indicates the minimum tensile strength of the deposited metal (430mPa); E means welding rod.
(2) Gas welding materials
Gas welding materials mainly include welding wire and flux.
1. Welding wire
Gas welding generally uses welding wire as a filler metal. The composition of the welding wire should be basically the same as that of the welded part. The diameter of the welding wire is determined by the thickness of the welded part. In principle, use a larger diameter welding wire as far as possible under the premise of ensuring the quality.
2. Flux
When welding high-alloy steel, cast iron and non-ferrous metals, it is necessary to use flux to match the welding wire. The function of the flux is to prevent oxidation of the solder metal and remove oxides. When welding cast iron, soda or potassium carbonate is often used as flux; when welding other metals, borax or boric acid is often used as flux.