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Unformatted text preview: 13.2 Ferrous Alloys
Metal alloys ● 403 Ferrous Nonferrous Steels Cast irons Low alloy Gray iron Ductile (nodular) iron White iron Malleable iron High alloy Low-carbon Medium-carbon High-carbon Plain High strength, low alloy Plain Heat treatable Plain Tool Stainless FIGURE 13.1 Classiﬁcation scheme for the various ferrous alloys. carbon, which is normally less than 1.0 wt%. Some of the more common steels are classiﬁed according to carbon concentration, namely, into low-, medium-, and highcarbon types. Subclasses also exist within each group according to the concentration of other alloying elements. Plain carbon steels contain only residual concentrations of impurities other than carbon and a little manganese. For alloy steels, more alloying elements are intentionally added in speciﬁc concentrations. Low-Carbon Steels
Of all the different steels, those produced in the greatest quantities fall within the low-carbon classiﬁcation. These generally contain less than about 0.25 wt% C and are unresponsive to heat treatments intended to form martensite; strengthening is accomplished by cold work. Microstructures consist of ferrite and pearlite constituents. As a consequence, these alloys are relatively soft and weak, but have outstanding ductility and toughness; in addition, they are machinable, weldable, and, of all steels, are the least expensive to produce. Typical applications include automobile body components, structural shapes (I-beams, channel and angle iron), and sheets that are used in pipelines, buildings, bridges, and tin cans. Tables 13.1a and 13.1b, respectively, present the compositions and mechanical properties of several plain low-carbon steels. They typically have a yield strength of 275 MPa (40,000 psi), tensile strengths between 415 and 550 MPa (60,000 and 80,000 psi), and a ductility of 25%EL. ...
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- Spring '08