Welding Carbon Steel
Carbon steel, also known as plain carbon steel, mild steel, and carbon-manganese steel, is the most widely used and the most frequently welded material. These materials are usually welded without problems, but as the carbon content of the steel increases it becomes more difficult to weld. This is due to phase transformations that take place during rapid cooling from elevated temperature. Steels with carbon contents above about 0.3% are hardenable, and fast cooling will produce a hard HAZ and this is liable to suffer hydrogen cracking. Using a low hydrogen process like MIG, or low hydrogen MMA, MCAW, or FCAW consumables, combined with preheat, can prevent this form of cracking. All common processes can be used to weld carbon steel, the most frequently used being MMA, MIG, FCAW, MCAW, SAW, TIG and gas welding. Standard equipment is usually suitable for welding carbon steel. There are a range of different mild steel type consumables and shielding gases that can be used as appropriate. Other welding problems presented by carbon steel include several different types of cracking. For example, contaminants like sulphur and phosphorous can contribute to solidification cracking and another form of cracking, known as lamellar tearing, caused by bands of inclusions can impair the through-thickness properties leading to failure. Welding these materials may present possible electrical, radiation, and noise hazards plus generation of welding fume.
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