Chapter 15 Introduction to Nonferrous Metals 325 Laboratory-purity metals recrystallize at lower temperatures than the same metals of commercial purity, and metals alloyed for applications near the melting point contain precipitates to force recrystallization at higher temperatures. Precipitates are compounds that separate from a solution upon cooling through a phase change. Figure 15-6 lists the recrystallization temperatures of several pure metals. ˚Fahrenheit 6192 2800 ˚Celsius 3422 1538 2200 1204 Kelvin 3695 Melting point of tungsten (W) Melting point of iron (Fe) 1811 Cast iron pour temperature 1478 1341 727 Austenite-ferrite steel transformation 1000 1220 660 Melting point of aluminum (Al) 933 449 232 Melting point of tin (Sn) 505 212 100 Boiling point of water (H2O) 373 32 0 Melting point of water (H2O) 273 –38 –39 Melting point of mercury (Hg) 234 –320 –196 Boiling point of nitrogen (N) 77 –460 –273 Absolute zero 0 10 0 Goodheart-Willcox Publisher Figure 15-5. The three common temperature scales have different origin points. Only the kelvin scale uses 0 to mean absolute zero, the absence of thermal energy. The melting points of certain elements are shown here, as well as the melting and boiling points for water, as a comparison. Copyright Goodheart-Willcox Co., Inc.