ARROW LABORATORY, INC.
Metallographic tests are usually made on cross sections cut from an appropriate location in the sample. For routine work, the size of the cross section is limited to about one inch square. The cross sections are generally mounted in plastic, ground and polished, and examined at 50 to 1600 magnifications. Various etchants are used to show specific structures. Sections are also examined unetched.
Metallographic tests are used to determine the type and quality of cast irons. The type of cast iron can be determined by the graphite structure and the strength and heat treatment can be estimated from the structure of the matrix.
Metallographic tests are routinely used to verify proper heat treatment of aluminum alloys. Anodize coating thickness can be measured on cross sections.
Steels may be annealed,normalized, quenched & tempered, carburized, and/or induction hardened. These and other conditions can often be identified from the microstructure of a steel. The effectiveness of thee treatments can also be evaluated. The internal quality of the material may be evaluated by examination of the non-metallic inclusions.
Corrosion, cracking, and wear
Examination of the microstrcture of cross sections from corroded, cracked, or worn areas may help in the identification or cause of the condition.
Many surface treatments can be identified and measured by examination of cross sections.