What are the Best Materials to Use for Oxy-Fuel Welding?

05 December 2018

Oxy-fuel, oxyacetylene, welding is a gas stoked process. As the label suggests, oxygen and acetylene are the twin fuels. Their co-mingling streams create a hot flame, which melts two in-contact metal surfaces. Cooling from 5,600°C, the white-hot weld zone becomes a single fused piece of metal. Having said all that, though, which metals respond best to this welding equipment?

Low-Carbon Steel

For mild steel, oxy-fuel welding raises the alloy’s temperature to 1,500°C. As the weld zone melts, a pool forms. Unfortunately, the area around the weld tends to oxidize. To combat this effect, the welder can set the flame mix to “neutral flame,” a point where the two fuels burn evenly. If a filer rod is needed to reinforce the weld joint, it must be composed of pure iron. Finally, heat warping defects are uncommon when this steel type is welded because the metal is ductile. However, if there are deformation issues, consider preheating the workpiece.

Medium-Carbon Steel

The job gets harder as the carbon content rises. Medium carbon steels are gas weldable, but high-carbon workpieces present problems. For starters, the metal becomes brittle and hard. Heat treatment work can eliminate this effect, but that means the process will take longer. Then, if the material oxidizes, the oxides tend to become locked in the cooling metal. Even when medium-carbon steels have a low melting point, oxyacetylene rigs take longer to create weld pools. Considering this issue, the fuel tanks could run low before the job finishes. Stuck again, the equipment won’t get far until a new pair of ox-fuel bottles is brought onsite.

Wrought Iron Welding

Bent into intricate shapes, wrought iron parts can be worked into various shapes. Oxy-fuel welding equipment is still commonly employed when those parts require a fusion mechanism. Also, oxy equipment can be used to braze damaged wrought iron components. However, the internal structure of an iron workpiece leans towards the “fibrous” region of the metal-grained spectrum, so it can be hard to fuse. Wrought iron fences and gates still employ oxy-fuel gear, and the equipment is also used on this malleable metal as a decorative cutting and welding tool.

Expert equipment operators set their flames to neutral, carburizing, or oxidizing. All it takes is a little manipulation of the gas regulation controller. With the flame set properly, welding procedures join mild and medium carbon steels, but they have more trouble with hardened steel. Those materials become brittle when they’re exposed to oxyacetylene heat. Wrought iron is also weldable here, as is stainless steel. For that latter alloy, complex preheating procedures are needed to manage undesirable heat treatment effects.