Solid welding wire

GMAW requires a solid wire electrode or a composite metal-cored electrode. Solid wire electrodes commonly are referred to as GMAW electrodes. The mechanical properties and strength of the weld deposit depend first on the chemistry of the wire and second on the type of shielding gas used (see Figure 1). Shielding gas is necessary to protect the weld from the atmosphere. Fabricators often prefer GMAW because the weld deposit is slagless and requires little or no cleanup, which increases efficiency.

Dirty Steel. Many classifications of GMAW wire exist, each with varying levels of deoxidizers. Highly deoxidized wire can tolerate light to medium levels of surface contaminants. For these applications, look for ER70S-6 wire, which has higher levels of silicon and manganese than an ER70S-3. You also can choose an intermediate electrode, ER70S-4, for applications requiring more deoxidizers than ER70S-3 but less than ER70S-6.

Remember to select GMAW wire from a creditable manufacturer to ensure consistent chemistry, diameter, and feedability from lot to lot or spool to spool. Some imported GMAW wires are labeled as ER70S-6 but actually conform to the European SG2 classification. Many European wires labeled as ER70S-6 do not meet ER70S-6 chemistry required by the American Welding Society (AWS) and therefore might not be suitable for your application.

Travel Speed. On blasted plate, solid GMAW wire performs well. On a plate with heavy mill scale, GMAW wire doesn't perform as well as metal-cored wire or flux-cored wire. Solid GMAW wires don't deoxidize mill scale as readily, affecting bead shape and travel speeds adversely.

Out-of-position Welding. Solid GMAW wire can be used for out-of-position welding using a short-arc procedure on thin materials, which yields low deposition rates. As an alternative, pulse-spray welding with these electrodes can increase the deposition rates while still providing out-of-position capabilities.

Mechanical Properties. Generally, the strength of a weld deposit made with a solid GMAW electrode is limited to the strength of the electrode. If you have a high-strength, low-alloy base material, it may be difficult to find a solid steel GMAW wire that will meet the base material requirements. For these applications, a metal-cored or flux-cored electrode might be more appropriate.

Postweld Operations. For certain modes of metal transfer with solid GMAW wire—such as short-arc and globular—some spatter may occur that requires postweld cleanup. Silicon islands can be deposited during GMAW that might need to be removed before painting or coating. However, GMAW with solid wire generally is a clean process that requires minimal postweld operations.