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多年以来,Lgnchburg铸造公司一直生产着要求具有特定布氏硬度范围的铸件,并且还要求在铸件精加工线以下金属基体的铁素体含量应小于15%。这些铸件必须够软以易于机械加工,但低于精加工线还得有足够的硬度以显示有良好的耐磨性能。应用数点法测定金属组织中铁素体的含量能获得可靠而又一致的结果。这个方面包括:1)清点若干个在已知大小的微观视场范围内的铁素体的点数;2)计算铁素体的百分含量。试样的制备是切割自铸件某一特定部位的断面,
Over the years Lgnchburg Foundry has been producing castings that require a specific range of Brinell hardness and also requires that the ferrite content of the metal matrix should be less than 15% below the casting finishing line. These castings must be soft enough to be easily machined, but below the finishing line there is enough hardness to show good wear resistance. The quantitative determination of the ferrite content in the metal microstructure by using the point method yields reliable and consistent results. This aspect includes: 1) Counting the number of ferrite points within a microscopic field of view of known size; 2) Calculating the percentage of ferrite. Preparation of the sample is cut from the casting of a particular part of the cross-section,