A study on the effect of heat supply on the microstructure of heat affected zone (HAZ) using MIG

In the engineering industry, welding is mostly used to create steel structures. There are many benefits to welding, including simple setup, great mobility, low manufacturing costs, and high welded joint efficiency. When it comes to joining ferrous and non-ferrous metals together during the welding process, Metal Inert Gas welding (MIG) is a remarkably dependable alternative to compare with the other welding techniques. The microstructure of the heat affected zone (HAZ) is the key aspect of this study that needs proper examination because it is believed that different heat supplies and different cooling methods would have varying effects on its HAZ. The parameter of this investigation includes mild steel filler rod (ER70S-6), carbon dioxide shielding gas, single pass welding, and mild carbon steel base metal. The advantages of using mild carbon steel are numerous. Most industrial sectors can use it to a great extent. It is very weldable, machinable, impressively strong, and has good ductility. This study will considerably benefit from the choice of this steel because it is inexpensive, simple to get, and simple to weld. Due to its high weldability property, the microstructure analysis done on this material grade will undoubtedly result in a proper finding at the conclusion of this research. Prior to taking optical images, the samples were carefully cleaned after the production process by grinding, polishing, and etching. An observational comparison study was done using the images that were obtained. Heat supply and microstructure's interaction was demonstrated to be parallel to one another. A slow and steady cooling method with a lower heat supply is expected to result in the formation of a finer microstructure and, by prediction, a stronger HAZ region with high toughness, high hardness, and high brittleness, while a rapid cooling method with higher heat supply results in the formation of a coarser microstructure and, by prediction, a weaker HAZ region with low toughness, low hardness, and low brittleness