Solid Wire Versus Flux-Cored Wire

There are two types of flux-cored wires — gas-shielded and self-shielded. Gas-shielded flux-cored wires require external shielding gas, and the slag is easy to remove. Consider using gas-shielded flux-cored wires when welding on thicker metals or in out-of-position applications. Gas-shielded flux-cored wires have a flux coating that solidifies more quickly than the molten weld material. As a result, it creates a shelf to hold the molten pool when welding overhead or vertically up. Self-shielding flux-cored wire does not require external shielding gas because the weld pool is protected by gas generated when flux from the wire is burned. As a result, self-shielding flux-cored wire is more portable because it does not require an external gas tank.

What to consider when choosing solid or flux-cored wire

Appearance

Many welders believe that weld appearance is an important factor. When working on materials less than 3/16-inch thick down to thin sheet metal (24 gauge), solid wire will produce a clean looking weld. For example, a short short-circuit transfer with .030-inch solid wire set at 18-19 volts with 160-170 amps and using 75 percent argon and 25 percent carbon dioxide shielding gas will usually produce little spatter, create a smaller heat heat-affected area and reduce chances of burn-through. As a result, many automotive enthusiasts who specialize in bodywork or those who work with thinner applications prefer solid wire in their operations.

Location

The welder must also consider the location of the jobsite when choosing between solid and flux-cored wire. In environments such as windy locations, solid wire or gas-shielded flux-cored wire are more difficult to use because exposing the shielding gas to wind can compromise the weld integrity. Typically, the loss of shielding gas will produce porosity visible in the weld bead.

On the other hand, self-shielded flux-cored wire is ideal for welding outdoors or in windy conditions. The welder does not have to set up windshields to protect the shielding gases from being blown away because the shielding gas is generated from the burning flux. Since self-shielded flux-cored wire does not require external shielding gas, it is also more portable than solid wire. This portability is ideal in agricultural applications where field equipment can break down far from the shop. If you are welding thicker metals (16 gauge and above), self-shielded flux-cored wire also provides excellent penetration.

Thickness, type of application and parameter settings

Many novice welders attempt to use a one-size-fits-all wire and shielding gas combination for multiple applications. The most common wire and gas combinations (for solid wire) are .035-inch- diameter wire used with a 75 percent argon and 25 percent carbon dioxide shielding gas. When welding thicker material, however, consideration needs to be given to welding power source output, as well as welding wire diameter. If the .035-inch wire is selected for thicker materials, and the power source is one that is plugged into a 115-volt circuit, the resulting amperage output may not be sufficient to make quality welds. This increases the risk of cold lap or lack of fusion.

Attempting to use too small of a solid wire for thicker applications (such as on A-frames of an automobile) increases the chance of lower penetration in the root and could require more than one welding pass. Misapplication of the solid wire (even though strong enough) may also not provide adequate penetration on thicker material.

Although more expensive than solid wire, flux-cored wire could help you gain productivity. Flux-cored wire typically has the ability to handle the welding of dirtier materials that may have higher levels of rust, mill scale or oil. Although cleaning is always the proper method of preparing the steel, flux-cored wires contain de-oxidizing elements that trap these contaminants in the weld pool and hold them in the slag coverage, typically preventing the associated weld problems found when welding dirtier steels. When compared to solid wire, flux-cored wire also increases penetration on the sidewalls and offers the advantage of better deposition rates (the amount of weld metal deposited in a given time period, measured in pounds per hour). Although the welder is initially spending more on materials for flux-cored wire, the savings are realized in the decreased production time.