porosity in the weld. Process variables Wire feed speed Arc voltage Electrode extension Travel speed Electrode angles Electrode wire type Shielding gas composition (if required) Reverse polarity (Electrode Positive) is used for FCAW Gas-Shielded wire, Straight polarity (Electrode Negative) is used for self shielded FCAW Contact tip to work distance (CTWD) Advantages and applications FCAW may be an "all-position" process with the right filler metals (the consumable electrode) No shielding gas needed with some wires making it suitable for outdoor welding and/or windy conditions A high-deposition rate process (speed at which the filler metal is applied) in the 1G/1F/2F Some "high-speed" (e.g., automotive) applications As compared to SMAW and GTAW, there is less skill required for operators. Less precleaning of metal required Metallurgical benefits from the flux such as the weld metal being protected initially from external factors until the slag is chipped away Porosity chances very low Less equipment required, easier to move around (no gas bottle) Used on the following alloys: Mild and low alloy steels Stainless steels Some high nickel alloys Some wearfacing/surfacing alloys Disadvantages Of course, all of the usual issues that occur in welding can occur in FCAW such as incomplete fusion between base metals, slag inclusion (non-metallic inclusions), and cracks in the welds. But there are a few concerns that come up with FCAW that are worth taking special note of: Melted contact tip – when the contact tip actually contacts the base metal, fusing the two and melting the hole on the end. Irregular wire feed – typically a mechanical problem. Porosity – the gases (specifically those from the flux-core) don’t escape the welded area before the metal hardens, leaving holes in the welded metal. More costly filler material/wire as compared to GMAW. The amount of smoke generated can far exceed that of SMAW, GMAW, or GTAW. Changing filler metals requires changing an entire spool. This can be slow and difficult as compared to changing filler metal for SMAW or GTAW. References American Welding Society, Welding Handbook, Vol 2 (9th ed.) "Flux Cored Welding." Welding Procedures & Techniques. 23 June 2006. American Metallurgical Consultants. 13 Sep 2006 <http://www.weldingengineer.com/1flux.htm>. Groover, Mikell P. Fundamentals of Modern Manufacturing. Second. New York City: John Wiley & Sons, INC, 2002. "Solid Wire Versus Flux-Cored Wire - When to Use Them and Why." Miller Electric Mfg. Co. 13 Sep 2006 <http://www.millerwelds.com/education/articles/article62.html>. History Of Flux Cored Arc Welding before 1950's