Material Symbols
The type of section line used to represent a surface varies according to the type of material.  Symbols generally used for various materials are shown in figure 15. However, the general purpose section line symbol used in most section view drawings is that of cast iron. The specific type of steel to be used will be indicated in the title block or parts list. Occasionally, with assembly section views, material symbols are used to identify different parts of the assembly.

Figure 15.  General symbols used to represent various materials  in section view.