Like I said before, that Piping & Fabrication will continue this post of Physical Metallurgy of Steel Chapter II, and here we getting more and more of information of piping materials.
It is the effective use by the metallurgist of the knowledge contained on this and similar phase diagrams that allows for the manipulation of properties of engineering materials by varying their chemistry and heat treatment. For steel, the principal phases and their properties are briefly summarized in the following list:
Austenite: A single-phase solid solution of carbon in gamma iron (FCC). It exists in ordinary steels only at elevated temperatures, but it is also found at room temperatures, but it is also found at room temperature in certain stainless steels (e.g., 18 Cr–8 Ni type) classified as austenitic stainless steels. This structure has high ductility and toughness.
Austenite: A single-phase solid solution of carbon in gamma iron (FCC). It exists in ordinary steels only at elevated temperatures, but it is also found at room temperatures, but it is also found at room temperature in certain stainless steels (e.g., 18 Cr–8 Ni type) classified as austenitic stainless steels. This structure has high ductility and toughness.
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| FIGURE A3.18 Iron-carbon equilibrium diagram |
Ferrite: Alpha iron (BCC), containing a small amount of carbon (0.04–0.05 percent) in solid solution. This phase is soft, ductile, and relatively weak. Cementite: Iron carbide, Fe3C, a compound containing
