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Use sulphur in steel and cast iron

Use sulphur / sulfur in steel and cast iron

It does not change the yield point and tensile strength of steel. Sulfur is present in the composition of any steel and due to the lack of boiling point, it is not very stable in religions. The main problem of steelmakers is related to the phenomenon of hot burst or red brittleness. So I try to reduce the percentage of sulfur as much as possible. Sulfur is an important factor in fine-grained steels. In fact, one way to increase machine building capacity is to add sulfur to the steel composition. When the cutting tool works on the surface of the part, due to the presence of manganese sulfate, the length of the pleats is shortened and they also play the role of lubricant, and as a result, the surface smoothness is increased.

Sulfur is a relatively low cost addition and it is the cheapest free machining addition agent. Addition of Sulfur along with close control over the degree of its addition is an important step in the steelmaking process. There are various ways to add Sulfur into liquid steels. Usually Sulfur is added in the liquid steel (temperature round 1650 deg C) in the form of stick Sulfur which is, essentially, elemental Sulfur. In such additions the expected Sulfur recovery is around bout 40 % to 50 %. The non recovered Sulfur easily ignites in air to form sulphur dioxide (SO2), a noxious gas with a strong, pungent objectionable odour. Since the density of the stick sulphur (2.05 gm/cc) is low and the boiling point (444.6 deg C) is also low, this Sulfur vapour generation, and subsequent SO2 fume generation, occurs before liquid steel reactions involving Sulfur can reach completion. Here, the steel reactions are essentially the formation of Mn Sulfur in the steel which is non odourous coupled with the vaporization of uncombined Sulfur which causes environmental pollution. In case of cored wire injection system the recovery of Sulfur is 60 % to 70 % with precise control of composition. In Sulfur cored wire, Sulfur is encapsulated in steel sheath, when injected into steel it can go in depth of liquid steel, where due to sufficient ferrostatic pressure, Sulfur bubbles slowly rises to surface and react efficiently in liquid steel. Also control of wire feeding with the help of wire feeder at desired speed ensures high recovery, precise composition control and less fumes generation. Thus the cored wire injection into the steel is environmental friendly due to less fumes generation and economical due to high recovery and less heat rejection. The chemical composition of Sulfur cored wire consists of 98 % minimum of S, 0.2% maximum of Si and 0.3 % maximum of moisture.