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Welding wrought iron is relatively easy when compared to other metal alloys such as stainless steel or aluminum, mainly because wrought iron is almost pure iron, and the slag fibers in the metal serve as a fluxing medium at temperatures suitable for welding.
Since this slag melts at a lower temperature than the iron base metal, it provides very good protection for the weld pool, preventing oxidation and acting as a barrier against outside contaminants.
Wrought iron is a very common iron with a variety of uses, from decorative to home security. Wrought iron security doors and window bars, gates and fences, patio furniture, fireplace grates, artistic sculptures, are just a few uses for this functional and easy-to-work-with metal. Some of the advantages of wrought iron are:
- It has very good tensile strength
- It is quite resistant to corrosion, making it ideal for outdoor use.
- It's highly resistant to fatigue.
Welding wrought iron can be accomplished by the hobby welder or professional welder alike. Wrought iron is a metal that has a very low carbon content, only about .035% in fact. The melting point of wrought iron is approximately 1500 degrees Centigrade. This type of iron is produced by heating and then melting ingots of pig iron in a large puddling furnace. Because of the slag mentioned earlier, wrought iron possesses a unique fibrous structure, as the slag is spread throughout the iron base metal in fibers and thread that tend to extend in the same direction as the iron is being rolled.
Several common welding processes have been applied to the welding of wrought iron, including forge, seam, spot, thermite, oxyacetylene, fash and butt welding. Because it's a soft metal, the pressure applied during welding should be just enough to product a strong union of the two workpieces. In forge welding, the wrought iron should be heated to at least 1350 degrees Centigrade. And as with most welding procedures, the workpieces should be throughly cleaned of any dirt and debris, oxides, grease, and any other foreign matter.
If submerged arc welding is being employed to weld wrought iron, the same type filler word and flux should be used as for welding low carbon steel (up to .15%). Also, during the first run, the welding speed should be kept lower so as to avoid excessive weld porosity.
This lower welding speed also applies if shielded metal arc welding is the method you're using to weld wrought iron. This allows the weld pool to retain a liquid state for a longer period of time before hardening, which in turn allows the trapped gasses to escape and the slag particles to rise to the surface, where they can then be removed. This makes for a less porous and much stronger weld.
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