Как заваривать коллектор / сварка чугуна в гараже

#DIY #welding #semiautomatic #manifold Many owners of modern or vintage cars sometimes experience serious problems with their exhaust manifolds cracking, forcing them to repair them somehow, as manifolds are currently quite expensive. The problem with welding manifolds is that they are extremely fragile and can easily crack. This means they can only be welded at low currents and at low temperatures. To quickly and efficiently weld them, you simply need to use special electrodes for welding cast iron. Also, if the manifold is overheated, it will crack immediately. Therefore, many people conclude that it's simply impossible to weld them and start saving up for a new one. They believe that welding will not only crack the manifold but also break it completely. However, some people looking to save money and time use special welding electrodes with a specially developed coating that allows them to weld cast iron without any problems. In addition to the special coating and high-quality electrodes overall, you also need to weld correctly. Remember that a mistake can cost the collector its life, and you, in turn, $1-2. Before welding, you need to know a few things. Cast iron is an iron-carbon alloy with a carbon content of over 2.14%. The high carbon content of cast iron affects its strength. For example, gray cast iron contains graphite. The presence of such materials in the metal weakens the metal to mechanical damage, so it is imperative to remember to exercise extreme caution when handling cast iron. Nowadays, TsCh-4 electrodes are used for welding cast iron, which are also used for welding copper. Many people are confused about why this type of electrode is needed. As mentioned above, when welding a cast iron exhaust manifold, avoid overheating the metal. Copper begins to melt at 700-800 degrees Celsius. This temperature is sufficient to prevent cracks and fractures in the cast iron component. Before welding the manifold, preheat it to 600-650 degrees Celsius. Be sure to begin welding immediately after preheating. Before heating and welding, be sure to clean the surface of the metal being welded of any contaminants. After cleaning and preheating, you can safely and, most importantly, quickly begin welding the exhaust manifold. 1. Cast Iron Welding is a welding technique for cast iron components. Cast iron is a difficult metal to weld. It is welded with consumable or non-consumable electrodes, with or without preheating. 2. Cast Iron Properties Cast iron is an alloy of iron and carbon. The carbon content of cast iron ranges from 2.14% to 6.67%. Carbon imparts hardness to iron alloys and reduces ductility and toughness. Carbon in cast iron occurs as cementite and graphite. The melting point of cast iron ranges from 1,150 to 1,200°C, which is 300°C lower than that of pure iron. Cast iron's thermal conductivity is lower than that of steel, but its coefficient of thermal expansion is similar. The electrical conductivity of cast iron depends on the distribution of graphite inclusions. When cast iron is rapidly cooled from temperatures above 750°C, the graphite transforms into cementite, transforming the cast iron from gray to white. A hardened structure with internal stresses forms, leading to cracks. 3. Welding Features Difficulties in welding cast iron include cracks due to graphite inclusions, carbon burnout, and pore formation in the weld. The formation of refractory oxides with a melting point higher than that of cast iron; its high fluidity. Cast iron is welded by manual arc welding with consumable (TsCh-4) or non-consumable (tungsten, carbon, graphite) electrodes, with or without heating. Welding stresses that arise in the weld during cooling of the metal are relieved by forging the welds. For hot welding, the metal is preheated to 500-700°C. Cast iron electrodes with rods of grades A and B are used - OMCh-1 and UZTM-74. The electrodes should be of large diameter - from 8 to 16 mm. To improve the quality of the weld when welding cast iron, the part is heated and slowly cooled after welding.