Welding consumables can be a tricky subject to navigate at the best of times, with tens of suppliers offering hundreds if not thousands of options, how do you know what is what? How do you know when to use specific consumables? Well you might just be in luck! Today with Lincoln Electrics 71 Series Cored wires blog, we hope to demystify this subject and really get to the (excuse the pun) core of the matter!
Flux Cored wires are often referred to as just plain old Cored wires. But they go by many other names too: Slag wire, gasless wire, cored wire, 71T8 wire, 71T1 wire and the list goes on! So what does it all mean? Let’s break it down to the very basics. Flux cored wires refer to a specific group of welding consumables which are made up of two parts – The steel “sheath” which is the typical outer steel wire that you see, and the flux core. This core is a special mix of mineral and metal powders that give the flux cored wire its special characteristics, and this is what makes each brand of wire unique and different to the next one. Think of it as the spices in a stew, everyone has a different recipe, and that effects how the stew tastes in the end.
Now we get to the really interesting part Gas Shielded and Gasless wires! As the name implies, one family of flux cored wires is welded using a gas shielding (Like MIG welding) while the other family is welded without gas (like stick welding). How and why is this possible and/or necessary? It all comes back to that secret recipe of the flux, gas shielded wires and self-shielded (or gasless) wires have fundamental differences in their recipes. Let’s start with the easier one – the Gas Shielded wire.
Gas Shielded wires
As the name implies, gas shielded wires are designed to be operated with an auxiliary gas shielding. This means that you should not (and cannot) weld without gas shielding. The reason is that gas shielded wires rely on the gas shielding to protect the weld from the surrounding atmospheric contaminants like Oxygen and Nitrogen. The flux melts to product slag and helps to shape the weld bead and support the molten weld metal while it solidifies; scrub out small amounts of impurity elements from the weld metal; and to alloy the weld metal with certain elements like Manganese, Silicon, Nickel and others. These wires are also often referred to by the American method of classifying wires and is often called a 71T1 wires (the most common variant of gas shielded wires being E71T1). These gas shielded wires are ideal for working in an indoors or where mechanical properties are important.
Gasless wires:
Gasless wires by contrast, should not be welded with gas shielding. In the same way that gas shielded wires depend on the gas shielding to protect the weld from contamination, gasless wires depend on the weld getting contaminated to start with! At least to some degree. The recipe of the core has certain elements in it like Aluiminium that very aggressively bonds with atmospheric contaminants like Nitrogen and makes them unable to negatively affect the weld metal. In the same way, if the contaminants elements are not available, then the weld metal will be left with these chemicals in it which will also negatively impact the welds performance. Gasless wires are ideal for working outdoors, were the option of gas shielding is not available or you are in a remote location.
How do you go about buying a flux cored wire in reality?
For starters, always look at the classification! It should always read the following: “AWS A5.20: E71T”. After that, it’s up to you depending on what you want. For the most common gas shielded wire, it should have a “-1” next, for the gasless wire, it will be “-8”. The rest will be supplementary information that provides clearer details of the make-up of the wire to users who are more familiar with classification standards. To make things even simpler, we can recommend some wires from the Lincoln Electric range of premium quality welding wires.
Lincoln Electric offer a complete range of 71 Series of core wires which are fully compliant with AWS standards. The most popular cored wires such as Outershield 71E-H (gas shielded) & Outershield NR-233 are easily identified by the classification outlined above.
The next time you use a roll of cored wire see if you can identify the classification?
