*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 per cent; 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. *Low-temperature carbon steels have been developed chiefly for use in low-temperature equipment and especially for welded pressure vessels. They are low- to medium-carbon (0.20 to 0.30%), high-manganese (0.70 to 1.60%), silicon (0.15 to 0.60%) steels, which have a fine-grain structure with uniform carbide dispersion. They feature moderate strength with toughness down to — 50°F (—46°C). For grain refinement and to improve formability and weldability, carbon steels may contain 0.01 to 0.04% columbium. Called columbium steels, they are used for shafts, forgings, gears, machine parts, and dies and gages. Up to 0.15% sulfur, or 0.045 phosphorus, makes them free-machining, but reduces strength. *LTCS is a Nickel based alloy steel plates especially used for low temperature applications below - 150 deg F. Mainly used in cryogenic construction of space ships, low temperature application in chemical plant below -55 deg C. Examples: SA-203 Steel Plate Grades A, B, D, E and F Nickle Alloy Steel Plates. For low temperatures (-150 deg F) Low Temperature Carbon Steel Tubes ASTM A334 Gr.1 ASTM A333——Seamless and Welded Steel Pipe for Low-Temperature Service: Mainly Grade： Grade 1, Grade 3, Grade 4, Grade 6, Grade 7, Grade 8, Grade 9, Grade 10, Grade 11 *ASTM A420 For LTCS Fittings. *A350-LF2 is a standard For Flanges. **Steel that are generally killed include: · Steels with carbon contents greater then 0.25% · All forging grades of steel. · Structural steels with carbon content between 0.15 to 0.25%. · Some special steel in the lower carbon ranges. See the classification of carbon steel clicking source links. *There is a relation between Killed carbon steel, LTCS, stainless steel, carbon steel(normal) and it is the iron,carbon and different alloying elements in varying quantity which makes them fall under different categories.