Selecting metal materials - Material families

Presenting the families of metal alloys in just a few pages, with a view to their choice in mechanical part design projects, leads to a few reductive biases:

• an exhaustive list of available alloys is excluded, and the reader will find only a few examples to illuminate the presentation. and [BM 5 075] provide access to sources;

• the advantages of the reference metal in each family will be briefly outlined, followed by information on microstructural aspects, mechanical properties and certain uses of the alloys. However, it is not the intention here to provide an exhaustive catalog of possible applications;

• steels are the first to be processed, in line with their dominant position, followed by aluminum alloys and copper alloys, which are well established. Magnesium and titanium alloys are less well known, but have a promising future. Among the other families, more specific orientations are emerging: nickel and cobalt alloys, alloys with special functions (low melting point, precious metals, refractories, nuclear materials), some of which are still not very widespread or well known (shape memory alloys, metallic amorphous alloys). Last but not least, metal-matrix composites are likely to grow in importance: they illustrate quite well the approach of "building" a microstructure that optimizes mechanical properties;

• the designation of metal alloys is still a battleground for all those — manufacturers, processors, scientists, merchants and users — who have an interest in the subject. Should we give priority to composition, certain mechanical characteristics, national or even American customs, or trade names? In the present case, the European Community is working to create a Euronorm nomenclature, with the 1992 texts for steels, and those under development for non-ferrous metals. Wherever possible, the reader will find in this text the European symbolic designation preceded by EN; however, it will sometimes be accompanied by older designations. An article is devoted to an abbreviated presentation of standardization.

As usual, alloying element concentrations are given in mass concentration, unless an atomic concentration is explicitly mentioned. As all materials are considered in the solid state, the quantity "density" will be used rather than density. The main mechanical properties stated are conventional yield strength R _e and conventional mechanical strength R _m , as well as distributed relative elongation at break A, Vickers...