What are the effects of sulfur, manganese, phosphorus, aluminum, nickel and copper on the weldability of cast iron?

Sulfur is the most strongly promoting element of cast iron welds to produce white tissues. Sulfur not only enhances the binding force of iron and carbon atoms, but also forms sulfides which distribute at grain boundaries, hindering the diffusion and precipitation of carbon. Especially for ductile iron, many research results show that sulfur is a strong hindrance to graphite spheroidization. Excessive sulphur may also lead to hot cracks in cast iron when welding iron. Therefore, sulfur is a harmful element and should be strictly controlled during welding. Manganese itself is also an element promoting the production of white cast iron from cast iron weld, but its promotion effect is weak. Manganese can enhance the binding force of iron and carbon atoms and reduce the eutectic temperature, which is not conducive to the precipitation of graphite. However, manganese and sulfur have a strong binding capacity, the formation of both manganese sulfide, can reduce the harmful effect of sulfur. Therefore, in cast iron welding, the presence of a certain amount of manganese in the weld is often advantageous, the general content of manganese in the weld should be controlled below 1%. Phosphorus has little effect on graphitization, but when the content of phosphorus in cast iron weld is too high, a large number of phosphide eutectic may be formed. Because of the high content of phosphorus in cast iron, this kind of phosphorus eutectic structure is often seen in its microstructure. The existence of this structure will reduce the mechanical properties of the weld, especially the toughness index. In addition, the presence of excess phosphorus may also lead to the occurrence of thermal cracks in cast iron welds. Aluminum is a kind of element which can obviously promote graphitization. Data suggest that aluminum can promote graphitization when the Omega Al is less than 1.9% in the weld. The reason for its promotion is aluminum oxides and nitrides, which can be used as the nucleation core of graphite. However, when the aluminum content is too high, it may form carbon carbide compound, which hinder graphitization. Nickel and copper are also elements that promote graphitization, and nickel has a strong diffusion ability in liquid state, which is also beneficial to weakening the whiteness of the semi-melting zone. However, these two elements are not strongly promote the graphitization of the elements, when the amount of small, its role is often not obvious enough. Strong carbide forming elements such as chromium, molybdenum and tungsten are all elements that strongly promote chilling. These elements not only have an obvious tendency to form carbides with carbon, but also can form some composite carbides with iron. Therefore, the content of cast iron should be strictly controlled. In cast iron welding, especially in ductile iron welding, sometimes calcium, barium and rare earth elements, such as yttrium and cerium, are often added to the welding material. The addition of these elements is suitable for graphitization of cast iron and promotes spheroidization of graphite.铜焊丝,Copper Welding Rods,铝焊丝,aluminium welding wire,镍焊条,Nickel electrode,药皮焊条,Flux Coated Brazing Welding Rods