Each classification of solid wire has unique benefits, limitations, and best uses. Following are some common types of solid wires, along with their attributes.
An ER70S-6 solid wire is the most common choice for welding mild steel. This widely available wire is found in general fabrication, and automotive welding applications and can be used for robotic welding, as well as to complete root passes for pipe welding and other critical or industrial applications. It offers smooth and consistent wire feeding, which helps support greater productivity (there is less downtime to address feeding issues), and the wire helps to increase consumable life. With the proper use, it creates smooth weld beads with a uniform tie-in.
Welding operators can use ER70S-6 solid wire with 100 percent CO2 to increase joint penetration or with an argon/CO2 blend to help minimize spatter. They should also be aware that these wires tend to generate silicon island deposits on the surface of the completed weld. They will need to remove these deposits prior to painting or other types of surface conditioning, which may increase the time for post-weld cleaning.
While solid wires generally generate low spatter levels on clean base materials, they may not be the best option for welding contaminated metals. If, however, there is no alternative, an ER70S-6 wire may be helpful for welding through light rust or mill scale. This wire contains higher silicon and manganese content, which act as excellent deoxidizers.
AWS ER70S-6
ER70S-3 solid wire is another common choice and is used primarily in applications where a clean-finished weld is important. Like an ER70S-6 product, this wire provides good wire feeding, but it also generates a clean weld deposit that can be ready to paint or plate with very little post-weld cleaning. This solid wire is a common choice in automotive and automated welding applications, as well as general fabrication, light sheet metal fabrication, and applications requiring high wire feed speeds.
Also like an ER70S-6, this wire can be used with 100 percent CO2 or with an argon/CO2 mix, depending on if greater joint penetration or low spatter is the desired outcome.
When welding carbon and low-alloy steels, an ER80S-D2 low-alloy solid wire provides higher tensile and yield strength. This wire results in quality welds matched to meet the requirements of many high-strength applications, such as welding construction equipment, pipe, trailers, and more. The D2 designator indicates this wire is a manganese-moly alloy. Manganese is a deoxidizer that makes this wire a good option for rusty or dirty metals, and it also helps increase tensile strength. The molybdenum also offers hardenability, in addition to high-temperature strength.
The higher-alloy content in the ER80S-D2 wire can make the arc in a spray transfer mode slightly more difficult to control, resulting in increased spatter. To combat this issue, welding operators may prefer to use a pulsed MIG process instead.
Most solid wires available in the industry have a small amount of copper plating. This plating helps prevent corrosion of the wire and helps enhance the electrical conductivity between the contact tip (which is also copper) and the steel base material. Adding copper to certain steel base materials, however, can cause problems. In applications where that is a concern, welding operators may prefer to use a copper-free wire.
A benefit to copper-free wire is that it can be used at a slightly lower voltage in spray transfer mode, compared to the same wire with copper plating. For thinner materials, spray transfer mode allows for faster welding and a better deposition rate than short-circuit welding. This change in process can help reduce spatter and minimize heat in the arc to lessen the chance of burn-through.
When using a copper-free wire, companies need to be sure that the spool or coil of wire isn’t stored for long periods of time in the shop or on the Jobsite, as the absence of copper can cause the product to rust. A copper-free wire may also cause arcing between the contact tip and base material if the surface finish or lubricant isn’t correct; the welding operator may need to adjust welding parameters as a defense against this problem.
As with any welding operation, finding the right filler metal is key to gaining good productivity and quality, while also minimizing costs. Solid wires can offer versatility in many general fabrication applications that require the welding of mild steel and low-alloy steel. Always take care to select the right classification of wire for the job — based on the desired mechanical and chemical properties — and to consult with a distributor or filler metal manufacturer for assistance when in doubt about the best choice.
