The electrode is essentially a coated metal wire and should generally be made from a material similar in properties and composition to the metal being welded, and there are several factors that go into choosing the right electrode for your particular project.
While shielded metal arc welding (SMAW) or “stick” electrodes are consumable and become part of the weld, other electrodes (such as those used for TIG welding) are non-consumable, meaning they do not melt and become part of the weld. seam. Separation of the seam, in these cases, the use of an electrode is required.
We at Eng-weld know that choosing the right electrode is critical to weld strength, weld quality, spatter minimization and cleaning.
Cellulose electrodes are welding electrodes coated with a sheath containing organic materials. Usually about 30% by weight of the coating is cellulose, but in some parts of the world cellulose and wood flour may be added to the coating to reduce the pure cellulose content.
The various organic compounds in the electrodes will decompose in the arc to form carbon dioxide, carbon monoxide and hydrogen, all of which increase the voltage within the arc, resulting in a stronger and harder arc. Thus, cellulose electrodes can penetrate up to 70% deeper than compatible electrodes with the same current rating.
Usually manufactured with a thin or medium coating, although this produces slag that can be removed after the welding process is completed, this can result in significant spatter losses. However, the vertical down welding ability and the penetration ability of this electrode are very good due to gap filling in the coating.
The low hydrogen electrode is essentially a gas shielded arc welding (SMAW) consumable with a water content of less than 0.6% compared to the more traditional 4-6% water content of cellulosic electrodes.
Typically, low hydrogen electrodes such as the E7018 rod electrode provide users with low spatter and a smooth, stable and quiet arc. These properties make these electrodes an excellent choice for both experienced welders and beginners. The properties of these filler metal electrodes provide the welder with good arc control and minimize the need for post-weld cleaning.
Unlike other electrodes such as E6010 or E6011, low hydrogen electrodes provide superior deposition and penetration rates, allowing the welder to add more metal to the joint at any time, improving weld strength and avoiding welding defects such as lack of penetration.
Generally, mild steel electrodes provide a quiet and stable arc with low penetration, making them ideal for wide gap bridging and thin sheet applications. However, there are different types of mild steel electrodes, each with slightly different properties and thus better suited for different applications.
For example, grade 6013 is a general purpose mild steel electrode that provides deep penetration while maintaining a smooth and stable arc. The arc is easy to regenerate, the welding seam is beautiful, the spatter is less, the slag is easy to control, suitable for vertical down welding.
The 7018 arc electrode, on the other hand, is a mild steel electrode designed for welding high-strength carbon steel materials. This electrode is often used for structural welding due to the weld’s crack resistance. But this creates a lot of slag, which is not suitable for vertical down welding.
The last mild steel electrode we will see is 6011. This versatile deep penetration electrode provides a smooth and stable arc when welding galvanized mild steel and some other low alloy steels. Its coating creates a powerful arc of deep penetration, and the slag layer is thin and easy to remove.
Like the other electrodes we have seen above, stainless steel electrodes come in several varieties, each slightly different from the previous one.
Here we look at 3 different grades of stainless steel electrodes, 308, 309 and 316, and when to use them.
If you are using grades 301, 302, 304, 305 and casting alloys CF-3 and CF8, then we recommend that you use 308L, including ER308LSi electrodes. These stainless steel electrodes are ideal for austenitic stainless steels, but for applications such as power generation, we recommend the 308H electrode as this high carbon electrode provides better creep resistance at high temperatures.
When joining mild steel or mild steel alloys to stainless steel, use 309L, including ER309LSi. The same applies to joining different stainless steels such as 409 or 304L stainless steel. In addition to this, they should also be used to bond 309 base metals.
When using base metals 316L and 316 and their cast equivalents CF-8m and CF-3M, only 316L should be used as filler metal, including ER317LSi.
Some 308L applications can replace 309L as filler metal as they do not require molybdenum unlike 316 or 316L applications which require molybdenum so you cannot replace 309 with 316.
As we saw above, there is a wide variety of electrodes available. Each of them has slightly different properties and therefore slightly different and unique features. When carrying out any repair and maintenance work, care must be taken to ensure that the electrodes used have the required characteristics.
First, determine what kind of metal you will be repairing or servicing. Then you must decide if you need a general purpose electrode or an electrode with special properties. Once you have all this information you can start soldering, if you don’t and use the wrong electrodes your solder will most likely fail or you could just burn through the metal you are working with.
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