Why the preparation is required for the microscopic examination
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1. PREPARATION OF SPECIMEN FOR MICROSCOPIC EXAMINATION Deep Patel : U13ME235 B. Bharath : U13ME236 B. Tech II, IV Semester MATERIALS SCIENCE & METALLURGY DEPARTMENT OF MECHANICAL ENGINEERING
2. Introduction and Purpose Metallography is the study of the physical structure and components of metals, typically using microscopy. Precision metallurgical sample preparation is a key step in performing reliable metallurgical testing. Facilitate examination and interpretation of microstructural features. Ex. To find out various phase present in material. Improper preparation methods may obscure features, and even create artefacts that may be misinterpreted.
3. Brass Cu 60, Zn 40 (wt%)
4. Selection of piece from main product It is important to study something that is representative of the whole specimen. Cutting of that representative part must also be done very carefully. Operations such as shearing produce severe cold work, which can alter the microstructure of a sample. Al-Mg alloy (a) cast condition showing constituent particles in the grain boundaries (b) ECAP (equal-channel angular pressing) condition showing shear bands (a part of it is marked by a white bar) introduced into the matrix (c) elongated grains in the shear band (d) fairly unchanged grains in the matrix, which is similar to the extruded condition
5. Selection of piece from main product Abrasive cutting (sectioning) offers the best solution to eliminate these undesirable features; the resultant surface is smooth, and the sectioning task is quickly accomplished. Low-speed cut-off wheels are utilized in cases where the heat created by standard abrasive cutters must be avoided. Ample coolant and proper speed control are essential in all sectioning operations.