Sectioning

Sectioning

Many metallographic specimens are used for process control. Separate test pieces or coupons attached to castings or forgings should be designed so that a minimum of sectioning is required for producing metallographic specimens.

Important uses of metallography other then process control include: examination of defects that appear in finished or partly finished products and studies of parts that have failed in service. Investigations for these purposes usually require that the specimen be broken from a large mass of material, and often involve more than one sectioning operation.

Many metallographic studies require more than one specimen. For example a study of deformation in wrought metals usually requires two sections - one perpendicular to, and the other parallel to, the major axis of direction of deformation. Failed parts may best be studied by selecting a specimen that intersects the origin of the failure, if the origin can be identified on the surface. Depending on the type of failure, it may be necessary to take several specimes from that area of the failure and from adjacent areas.