Metallographic microscope is mainly composed of optical system, lighting system, mechanical system and auxiliary devices (including other devices such as photography or microhardness). According to the light reflection characteristics of different tissue components on the surface of metal samples, these tissue components are optically studied and qualitatively and quantitatively described by microscope in the visible range. It can display the characteristics of metal structures in the scale of 500 ~ 0.2m As early as 184 1, Russians (ппансов) studied the patterns on Damascus steel swords under a magnifying glass. By 1863, the British (H.C.Sorby) transplanted petrographic methods, including sample preparation, polishing and etching, into the study of steel, developed metallographic techniques, and later took a batch of low-magnification metallographic photos and other tissues. The scientific practice of Soapy and his contemporaries A Martens and F Osmond laid the foundation for modern optical microscopy. By the beginning of the 20th century, optical metallography was becoming more and more perfect and widely used in the microscopic analysis of metals and alloys. Up to now, it is still a basic technology in metallographic field.
Metallographic microscope is a kind of microscope with visible light as illumination source, which is divided into vertical microscope and inverted microscope. The difference between the two is that:
The invention has the advantages of short optical path, simple optical path design, small optical loss, high sample preparation requirements, high sample height requirements, convenient multi-field continuous observation and easy lens maintenance.
Inverted microscope has long optical path, large optical loss, complex optical path design, low requirements for sample preparation, no requirements for sample height, convenient and fast detection, and is not suitable for multi-field analysis. Under the same configuration, the price of inverted microscope is higher than that of upright microscope.
Axle mirror a 1
The inverted axis is vertical. A 1
Application of metallographic microscope in iron and steel metallurgical industry;
● Identify the microstructure after various cold and hot working treatments.
Identify and evaluate nonmetallic inclusions in steel.
● Grading of various organizations.
● Measurement of decarburized (carburized) layer
● Particle size grade
● Organizational structure measurement
● Fracture analysis
Application of metallographic microscope in nonferrous metal industry
1. The quality of aluminum alloy products is judged by metallographic examination, and the causes of various defects are discussed, so as to improve the process and product quality.
2. Check the crack size with metallographic microscope to judge the oxygen content in copper oxide; Particle size evaluation, etc.
3. Evaluation of microstructure and grain size of magnesium alloy products.
4. Inspection of high and low macro-structure of dual-phase titanium alloy
5. Metallographic examination of iron-based and copper-based products
6. Metallographic examination of steel bonded cemented carbide
7. Metallographic examination of cemented carbide
8. Tissue identification and evaluation after surface treatment of materials.
Matters needing attention in purchasing metallographic microscope:
Metallographic microscope is a kind of high-value and high-precision optical instrument, and its core part is optical imaging system. The quality of products is related to the imaging effect and the accuracy of analysis and judgment. Pay attention to the following two points when purchasing metallographic microscope:
First, in terms of imaging quality, four basic conditions should be met at the same time. Metallographic microscope uses the principle of optical imaging to obtain the image of metal microstructure (i.e. metallographic diagram), and then makes qualitative and quantitative analysis on the metallographic diagram. Image quality is the primary index to measure the quality of metallographic microscope. In order to obtain a clear image, four basic conditions must be met: Gao Fancha, high brightness, good color reproducibility and high resolution. The first three conditions are the most easily overlooked by users when choosing models. Users should not blindly pursue resolution and ignore the other three aspects when purchasing. Only in this way can they achieve value for money and make the best use of it.
Secondly, the continuous stability of the mechanical properties of metallographic microscope should be considered in use. In addition to the imaging quality, we should also consider the long-term stability of the instrument to maintain the best working condition under normal use, which is called the continuous stability of mechanical properties. Metallographic microscope is a high-value and high-precision optical instrument with a service life of more than 30 years. When purchasing, users should also examine the materials selected by manufacturers, manufacturing accuracy and scientific and reasonable mechanical design. Long-life microscope should use cast iron as the main manufacturing material to avoid using too many functional plastic materials. At the same time, in order to maintain a long service life, it is necessary to carry out anti-mildew treatment on optical elements, mainly by coating anti-mildew to avoid purchasing drugs. The mechanical gear device should ensure long-term high-strength use without slipping and stable performance, and the harmonic gear is the first choice. The above-mentioned necessary conditions put forward more clear requirements for manufacturers in manufacturing from a practical point of view, and users should also follow the above principles to purchase economical and applicable metallographic microscopes.
Third, the choice of parameters, users should not blindly pursue the level of various parameters in the selection process. Because different manufacturers adopt different technical means, the parameters of different manufacturers are not comparable, and the best measure is the imaging quality of their own proofs. At present, all manufacturers provide free sample photo, prototype inspection and other services, and users can make a choice after comparing the imaging quality of each manufacturer in detail.
Four, after-sales service, users in the process of purchasing equipment, the quality of after-sales service that manufacturers can provide should also be included in the main indicators of assessment. Because even the best equipment may break down, whether the manufacturer can provide timely and effective service often directly affects our daily work, especially in the departments with heavy testing tasks, we should pay more attention to the quality of after-sales service. What aspects of after-sales service should users pay attention to during the purchase process? 1, the strength of the after-sales service department of the manufacturer (such as the number of after-sales engineers, working ability, distribution of after-sales points, etc.). ), 2, the degree of perfection of the manufacturer's after-sales service system, such as whether the after-sales service is active or passive, the after-sales response time, the time for engineers to arrive at the maintenance site, and the connotation of after-sales service.
5. Value-added service refers to that manufacturers provide targeted training programs according to users' actual operation level and mastery of relevant application knowledge while providing perfect after-sales service, so as to improve users' application level and provide certain guidance for users in the actual work of product testing. Therefore, value-added service is very important for users who buy microscope equipment for the first time or have a poor grasp of relevant knowledge.
Sixth, the price factor, especially the price of imported equipment, is often one of the most critical factors affecting the decision-making process. However, the price factor should be fully considered on the basis of the above five factors before choosing the price as the final decisive factor. If we blindly consider the price and lack it in other aspects, it will inevitably bring the same amount in future use, and even lead to the failure of the final choice.
Metallography room was established in the early 1990s. After more than ten years of gradual development and continuous improvement, it has successively passed the laboratory accreditation of the National Accreditation Committee, the accreditation of the testing center of metallurgical industry engineering quality supervision station, and the three-in-one management system certification, and participated in the compilation of Shanghai engineering construction specification DG/TJ08-2011-2007. Now it is a professional metallography room.
At present, the metallographic room is equipped with first-class metallographic sample preparation and detection equipment at home and abroad, which is flexible to operate. Coupled with the metallographic image analysis system, the detection work can be truly integrated. It can carry out on-site coating metallographic examination, routine laboratory metallographic examination, failure analysis and judicial appraisal of parts, equipment and systems, and cooperate closely with large testing institutions and scientific research institutes, greatly improving the evaluation level of metallographic room in the field of failure analysis and quality accidents.
The first step of the test content is sample preparation. First, rough grinding with coarse sandpaper (180 mesh), then rough grinding with 600 mesh sandpaper, and finally rough grinding with 1000 mesh. After polishing, polish with flannel to achieve mirror effect. The second step is corrosion. Carbon steel and low alloy steel are corroded with 4% (volume ratio) nitric alcohol 15~20 seconds, and high alloy steel and stainless steel are corroded with aqua regia alcohol 1~4 minutes. 1 routine inspection of welded joints, metallographic examination of various fasteners and raw materials, cast iron, cast steel, nonferrous metals and raw materials, determination of metal hardness (HV, HRC, HB, HL), inspection and evaluation of microstructure of various metal materials, determination of grain size, nonmetallic inclusions and depth of decarburized layer/carburized hardened layer, etc. 2. On-site coating inspection refers to nondestructive tissue inspection of steel (iron) water bags, iron mixing trucks, traveling cranes, various pressure vessel pipelines and special equipment, and the test results are accurate. The inspected equipment is not damaged.