Composition and Classification of Metallurgical Microscopes
Metallurgical microscopes are high‑tech instruments developed by integrating optical microscopy, photoelectric conversion and computer image processing technologies. Metallographic images can be conveniently viewed on a computer for metallograph analysis, grading, as well as image export and printing. They are classified into upright metallurgical microscopes (GPM‑100, IDL‑100), inverted metallurgical microscopes (MG‑MI, GX51, GX41), portable field metallurgical microscopes (MG‑100), and so on. As is well known, alloy composition, heat treatment processes and cold/hot working processes directly alter the internal microstructure of metallic materials, which in turn changes the mechanical properties of components. Therefore, observing, inspecting and analyzing the internal microstructure of metals with a metallurgical microscope is an important method in industrial production.
A metallurgical microscope mainly consists of an optical system, an illumination system, a mechanical system and accessory units (including photographic equipment or microhardness testing devices, etc.). Based on the light reflection characteristics of different microconstituents on the surface of metal specimens, the microscope conducts optical studies on these constituents within the visible light spectrum for qualitative and quantitative characterization. It can reveal metallic microstructural features at scales ranging from 500 μm down to 0.2 μm.
As early as 1841, the Russian scientist P. P. Anosov studied the patterns on Damascus steel sword blades under a magnifying glass. In 1863, the
British scientist H. C. Sorby introduced petrological techniques, including specimen preparation, polishing and etching, into the study of iron and steel and established metallography. He also took a series of low‑magnification metallographs of microstructures. The research work of Sorby, together with his contemporaries A. Martens (Germany) and F. Osmond (France), laid the foundation for modern optical metallography. By the early 20th century, optical metallography had matured and been widely applied to the microanalysis of metals and alloys, and it remains a fundamental technique in the field of metallurgy to this day.
