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Why should stainless steel precision tubes be subjected to metallurgical examination?

Why should stainless steel precision tubes be subjected to metallurgical examination?

Time:2022-04-13 Source:China Wuxi JiaNuo Special Steel Co.

From the metallographic point of view, because the stainless steel precision tube contains high chromium, chromium in the surface to form a very thin chromium film, this film isolated from the invasion of oxygen in the steel, thus playing a role in corrosion resistance. For stainless steel tubes, the most important thing is undoubtedly the anti-corrosion properties of the material and the chemical composition analysis. The composition of the steel pipe, heat treatment process, hot and cold processing process directly affects its internal organization, structural changes, thereby causing changes in mechanical properties.

Therefore, the use of metallographic analysis to observe and test the internal organization of the tube is an important means of industrial production, stainless steel precision tube commonly used metallographic observation test can be divided into the following four areas: 1.

1, raw material inspection: the metallurgical quality of raw materials to check the situation, such as: composition deviations, non-metallic inclusions distribution type and level; casting material casting looseness, porosity, slag organization uniformity; forging parts of the surface decarburization, overheating, overburning, cracks, deformation, etc..

2. Quality control in the production process: metallographic analysis can provide the basis for adjusting the process and modifying the process parameters to guide production, such as whether the heat treatment quenching heating temperature, holding time, cooling rate, etc. is appropriate; control of chemical surface heat treatment process parameters; whether the starting and final forging temperature of forging is appropriate, etc.

3. Product quality inspection: some precision stainless steel tubes not only require mechanical properties, physical properties indicators, some also require its microstructure parameters, used as one of the technical indicators of quality assessment.

4, failure analysis: metallographic organization analysis methods are widely used in mechanical failure analysis, the identification of some common defects is very convenient. Such as stainless steel welded pipe surface decarburization; microcrack morphology and distribution characteristics; chemical heat treatment defects; abnormal organization after heat treatment; grain boundary brittle phase precipitation, etc.. The results of these metallographic analyses are often used as the basis for failure analysis.

In addition, in the metallographic testing needs to do the following two aspects of preparation: First, for the composition of the material structure and performance of a large number of tests and research, through theoretical data to complete the understanding of the material; Second, according to the characteristics of the material for comparison and regularity of the study, so as to know the common characteristics of the material and special properties, which is extremely important for the metallographic test. Guidance significance.

The above is why the stainless steel precision tube for the content of the metallurgical examination. The diversity of steel tube performance and organization has a close relationship. Secondly, the need to be in the metallographic test before the material should be in-depth understanding of the common characteristics and special properties of the material between. Therefore, the metallurgical test to determine the process performance of stainless steel precision tube, mechanical properties, corrosion resistance and so on can meet the application requirements, has become increasingly important.