GB/T 37787-2019Metallic materials—Determination of microporosity—Fluorescence method (English PDF)

GB/T 37787-2019 is the English-translated version of 金属材料 显微疏松的测定 荧光法.

GB/T 37787-2019 specifies the fluorescence method for the determination of the area percentage content of microporosity in metallic materials, setting out the sample preparation, the microscope configuration, the measurement, the measurement accuracy and the test report.

Clause 1 states that it applies to the determination of that content in as-cast metallic materials and 3D printed metallic materials, and that the determination of the pore content in other materials such as ceramics and powder metallurgy materials may refer to it.

Clause 2 cites GB/T 8170, GB/T 13298, GB/T 15749-2008 and GB/T 30067, and clause 3 takes its terms from GB/T 30067, repeating some of them and defining microporosity as very fine pores in the casting.

Clauses 4 and 5 cover sample preparation and microscope configuration.

Clause 6, Measurement, ties the number of view fields to the corresponding product standard or the agreement between the two parties and, where nothing is required, calls for at least five random view fields measured without repeat overlay, with the average taken as the measured value, although the result may instead be expressed as the area percentage content of the most serious view field.

The same clause gives two measurement methods: the quantitative metallographic manual measurement method, which collects microporosity photographs by the fluorescence imaging method of a metallographic microscope and then counts them under GB/T 15749-2008 by the grid counting pixels method or the microscopic micrometer eyepiece determination method, and the image analysis measurement method, which checks the magnification of the image, loads the ruler, extracts the microporosity by binary segmentation and measures it with the two-phase or multi-phase area percentage function of the software; in case of dispute the image analysis measurement method is used as the arbitration method.

Clause 7 covers measurement accuracy and clause 8 the representation of the result, where the content of the most serious view field is expressed as a percentage retaining one digit after the decimal point and rounded according to GB/T 8170.

Clause 9 requires the test report to carry the standard number, the sample name, material and specifications, the ratio of fluorescent infiltrant, the vacuum degree and the infiltration time, the area percentage content of microporosity, and the test report number and date, and an informative appendix compares pictures taken before and after fluorescent infiltration. It was issued on August 30, 2019 and has applied since July 1, 2020.

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This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 15 pages — is available in the English PDF.

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