Low Carbon Steels

The body-centered-cuhic (bcc) metals and alloys are normally classified as undesirable for low temperature construction. This class includes Fe, the martensitic steels (low carbon and the 400-series stainless steels). Mo, and Nb. If not brittle at room temperature, these materials exhibit a ductile-to-brittle transition at low temperatures. Cold working of some steels, in particular, can induce the austenite-to-martensite transition. 

Nickel Steel Low-carbon 9 percent nickel steel is a ferritic alloy developed for use in cryogenic equipment operating as low as —I95°C (—320°F). ASTM specifications A 300 and A 353 cover low-carbon 9 percent nickel steel (A 300 is the basic specification for low-temperature ferritic steels). Refinements in welding and (ASME code-approved) ehmination of postweld thermal treatments make 9 percent steel competitive with many low-cost materials used at low temperatures. 

Iron Low-carbon steels Low-carbon alloy steels Decarburised malleable Chromium 980-1 050 (Halide) 1. Gaseous 2. Semi- gaseous 3. Pack 25-75 urn Solid-solution (ferritic) 20-25% Cr Ductile (200-300 HV) Weldable Heat treatment acceptable ... 

The tensile strength and elastic modulus of metals decrease with increasing temperature. For example, the tensile strength of mild steel (low carbon steel, C < 0.25 per cent) is 450 N/mm1 2 3 4 at 25°C falling to 210 at 500°C, and the value of Young s modulus... 

His calculated cost ratings, relative to the rating for mild steel (low carbon), are shown in Table 7.6. Materials with a relatively high design stress, such as stainless and low alloy steels, can be used more efficiently than carbon steel. 

Without these advances in hard, strong materials based on abundant, and therefore low-cost iron ore, there could have been no industrial revolution in the nineteenth century. Long bridges, sky-scraper buildings, steamships, railways, and more, needed pearlitic steel (low carbon) for their construction. Efficient steam engines, internal combustion engines, turbines, locomotives, various kinds of machine tools, and the like, became effective only when key components of them could be constructed of martensitic steels (medium carbon). 

Gas carbonitriding creates a diffused carbon and nitrogen case. Base niciuls are low carbon steels, low-carbon alloy steels, and stainless steels. Proofs temperature range is 7W)-870JC 11400-1600 K). 

Al alloy 5052 Al alloy 5056 Al alloy 6061 Al alloy 6063 AlClad alloy 7075 Al alloy 3003 Al alloy 7075 AlClad alloy 2024 Al alloy 2017 Al alloy 2024 Zinc Zn-plated steel Cd-plated steel Low-carbon steel Stainless steel Monel, titanium Lead, copper, brass... 

Cast irons High-carbon steels Medium-carbon steels ----Low-carbon ("mild") steels... 

Austenitic nictel cast iron 9 I Low-alloy steel Low-carbon steel, cast iron 1 ... 

Materials suitable for fineblanking are steels (low carbon, unalloyed and alloyed carbon steel, and stainless) and nonferrous metals (aluminum alloys, copper, and copper alloys). The input material selection influences extensively the quality of sheared edges and the tool life. Low-carbon steels are most suitable. Unalloyed steels can be fmeblanked with a carbon content of up to 1% with a spheroidal... 

The flow system used in this investigation is shown in Figure 1. The reactors were constructed from 0.635 cm O.D. (1/4-inch O.D., 20-gauge) tubing. The tubing was coiled to a diameter of 12.7 cm, and about 4.52 to 4.62 m of tube were immersed in a fluidized sand bath to obtain the desired temperatures. A total of seven reactors were used in this study. Reactors were constructed of 304 stainless steel, low-carbon steel, nickel, inconel, and incoloy, all commercially available. 

Nickel-based alloys can also be subjected to carbide precipitation and precipitation of intermetallic phases when exposed to temperatures lower than their annealing temperatures. As with austenitic stainless steels, low-carbon-content alloys are recommended to delay precipitation of carbides. In some alloys, such as alloy 625, niobium, tantalum, or titanium is added to stabilize the alloy against precipitation of chromium or molybdenum carbides. Those elements combine with carbon instead of the chromium or molybdenum. 

Pack Difffised carbon 815-1090 (1500-2000) 125 pjn-1.5 mm (5-60 mils) 50-63(a) Lx>w-carbon steels, low-carbon alloy steels Low equipment costs, difficult to control case depth accurately... 

Liquid Diffused carbon and possibly nitrogen 815-980 (1500-1800) 50 pjn-1.5 mm (2-60 mils) 50-65(a) Low-carbon steels, low-carbon alloy steels Faster than pack and gas processes, can pose salt disposal problem, salt baths requite frequent maintenance... 

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