Chapter 15 Introduction to Nonferrous Metals 347 Chapter Wrap-Up This chapter focuses on basic metallurgical principles—the same principles used to explain steel in previous chapters. The cry stal structures of many nonferrous metals are the same as found in steel, and all metal crystals form grains. Dislocation tangles develop in exactly the same way as in steel, and recrystallization removes tangles exactly the same way. Thus, improving the properties of nonferrous metals through hot and cold work follows the same mechanisms as for improving the properties of steel. Nonferrous metals melt at different temperatures, and so we need to examine temperatures as a percentage of the melting point on the kelvin scale, not the Celsius or Fahrenheit scales. Some nonferrous metals can be strengthened by solid solution alloying, some by forming very large precipitates, and some by precipitation hardening. The process cycle for precipitation hardening may look similar to a steel heat treatment, but what is happening inside the metal at the microscopic level is very different. The property changes at each step are different, and the time frame for each step can be much different. Other process methods for nonferrous metals are similar to those for steel, with the primary differences following from different melting points and the chemical reactivity of the metal. Joining procedures are similar as well, once the issue of parent metal compatibility is resolved. Thus, while this chapter focuses heavily on fundamentals, most principles have been discussed previously, and the behaviors of nonferrous metals are very similar to those of steel that we have already seen. In the following chapters, we will discuss individual metals, where the unique characteristics of primary metals are used to achieve the properties we want. Copyright Goodheart-Willcox Co., Inc.