Carbon and low alloy steels...

Carbon and low alloy steels  The definition of the carbon steels by American Iron and Steel Institute (AISI) is as follows: “Steel is considered to be carbon steel when no minimum content is specified or required for chromium, cobalt, columbium [niobium], molybdenum, nickel, titanium, tungsten, vanadium or zirconium, or any other element to be added to obtain a desired alloying effect; when the specified minimum for copper does not exceed 0.40 %; or when the maximum content specified for any of the following elements does not exceed the percentages noted: manganese 1.65 %, silicon 0.60 %, copper 0.60 %.” Steels can be classified based on different systems depending upon: The composition: Carbon, micro alloy, low alloy, high alloy or stainless steel. The manufacturing processes: Open hearth furnace, basic oxygen process, energy optimizing furnace or electric arc furnace. The finishing methods: Hot rolling, cold rolling or forging etc. The type of product: Flat such as plate, sheet, strip, long such as wire rods, reinforcement bars, rounds and shapes, pipes and tubes or forged products. The de oxidation method: Killed, semi-killed, rimmed or capped steel The microstructure: Ferritic, austenitic, pearlitic, bainitic or martensitic The strength levels: HSS, HSLA or normal strength to meet standard requirement The heat treatment process: Annealing, normalizing, thermo mechanical treatment, quenching and tempering etc. Quality defining designations: Forging quality, commercial quality, drawing quality or welding quality etc. Carbon steels As a group carbon steels are the most frequently produced and used steels. More than 85 % of the steels produced presently are carbon steels. Variations in the carbon content of the steels have the greatest impact on the mechanical properties of steels. Increase in the carbon content also results into increase in the hardness of the steels as well as their strengths. Hence carbon steels are generally...