Introduction to the analysis of various metal structures under a metallographic microscope
For many years, metallographic workers have often observed the polished surface of metallographic specimens under a microscope to qualitatively describe the microstructural characteristics of metal materials, or evaluated the microstructure, grain size, non-metallic inclusions, and phase particles by comparing them with various standard images. This method has low accuracy and subjectivity in evaluation. The reproducibility of the results is also unsatisfactory, and they are all measured on the two-dimensional plane of the polished surface of the metallographic specimen. There is a certain gap between the measurement results and the true tissue description in three-dimensional space. The emergence of modern stereology provides a scientific method for extrapolating two-dimensional images to three-dimensional space, which can associate the data measured on the two-dimensional plane with the actual microstructure shape, size, quantity, and distribution of metal materials in three-dimensional space. It can also establish an inherent relationship between the microstructure shape, size, quantity, and distribution of materials in three-dimensional space and their mechanical properties, providing reliable analytical data for scientific evaluation of materials.
Due to the uneven distribution of microstructure and non-metallic inclusions in metal materials, the determination of any parameter cannot be determined solely by observing one or several fields of view with the human eye under a microscope. Statistical methods are required to perform extensive calculations on a sufficient number of fields of view to ensure the reliability of measurement results. If only human eyes are used for visual evaluation under a microscope, the accuracy, consistency, and reproducibility are poor, and the measurement speed is slow. Some even cannot be carried out due to excessive workload. Image analyzer replaces human observation and manual calculation with advanced electronic optics and computer technology, which can quickly and accurately perform statistically significant measurements and data processing. It also has the characteristics of high accuracy, good reproducibility, and avoiding the influence of human factors on metallographic evaluation results. It is easy to operate and can directly print measurement reports. Currently, it has become an indispensable means in quantitative metallographic analysis.
Microscope image analyzer is a powerful tool for quantitative metallographic research of materials and a good helper for daily metallographic inspection. It can avoid subjective errors caused by manual evaluation and thus avoid the phenomenon of tearing. Although it is impossible and unnecessary to use an image analyzer every time in daily metallographic inspection, when there are abnormalities in product quality or the metallographic structure level is between qualified and unqualified and difficult to distinguish, an image analyzer can be used for quantitative analysis to obtain accurate results and ensure product quality. The application of image analyzer in metallographic analysis has expanded the detection items of metallographic examination, promoted the improvement of detection level, and is also very beneficial for enhancing the quality of detection personnel.
