BS-7590A-1992.pdf

BRITISH STANDARD BS 7590A:1992 (extracted from BS 7590:1992) Worksheet for the determination of volume fraction by systematic manual point count IMPORTANT NOTE. It is essential that this worksheet is used in conjunction with clauses 3 to 10 of BS 7590:1992. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:42:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7590A:1992 © BSI 10-1999 ISBN 0 580 21324 2 A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 3 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Amendments issued since publication Amd. No.DateComments Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:42:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7590A:1992 © BSI 10-1999i Contents Page A.1Worksheet1 A.2Symbols2 A.3Procedure for systematic manual point count2 Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:42:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii blank Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:42:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7590A:1992 © BSI 10-19991 A.1 Worksheet Field no. i PiField no. i PiField no. i Pi 11121 21222 31323 41424 51525 61626 71727 81828 91929 102030 NOTESee A.2 for symbols and A.3 for procedure. Fraction percentage Standard deviation s 95 % CI = Volume fraction Vv = Relative error = Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:42:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7590A:1992 2 © BSI 10-1999 A.2 Symbols A.3 Procedure for systematic manual point count A.3.1 Visually estimate the area fraction of the constituent or feature of interest on the metallographic section. A.3.3 If applicable, use Table 1 to select the grid size PT for optimum efficiency of counting. A.3.3 Superimpose the grid upon the microscope viewing screen or in the microscope eyepiece and select magnification such that the size of the features of interest are approximately one-half of the spacing between grid points. A.3.4 Select the relative error, e.g. 10 %, 20 %, or 33 %, desired for the measurement. The relative error is defined as follows: A.3.5 Using Tables 2 to 5, obtain an estimate of the number of fields, n, required to obtain the desired degree of precision. A.3.6 Determine the spacing between fields which will form a systematic (equally spaced) array covering a majority of the sample area without overlap. For example, on a 10 mm × 15 mm sample area where 40 fields are indicated from Tables 2 to 5, a 5 × 8 array of fields at 1.5 mm intervals might be used. A.3.7 Determine the number of turns required on the stage translation controls to move the stage from one field position to the next. Do not observe the image while translating to a new field to avoid bias in positioning the grid. A.3.8 Count and record the number of grid points Pi, falling within the feature of interest for each field. A.3.9 Count any point falling on the constituent boundary as one-half. A.3.10 Calculate the percentage of points Pp(i) within the feature of interest for each field A.3.11 Calculate the mean of Pp(i) A.3.12 Calculate the standard deviation estimate, s. PTTotal number of points in the grid PiPoint count on the ith field Pp(i)Percentage of the grid points on the ith field Mean of Pp(i) nNumber of fields examined sEstimate of standard deviation (Ö) CI95 % confidence interval VvVolume fraction as percentage Relative error = (7) (2) (3) (4) Pp Pp Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:42:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7590A:1992 © BSI 10-19993 A.3.13 Calculate CI, the 95 % confidence interval for. Where n 30 use the multiplier given in Table 6 in the equation for CI instead of the value 2. (5) Pp Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:42:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7590A:1992 BSI 389 Chiswick High Road London W4 4AL BSI British Standards Institution BSI is the independent national body responsible for preparing British Standards. It presents the UK view on standards in Europe and at the international level. It is incorporated by Royal Charter. Revisions British Standards are updated by amendment or revision. Users of British Standards should make sure that they possess the latest amendments or editions. It is the constant aim of BSI to improve the quality of our products and services. We would be grateful if anyone finding an inaccuracy or ambiguity while using this British Standard would inform the Secretary of the technical committee responsible, the identity of which can be found on the inside front cover. Tel: 020 8996 9000. Fax: 020 8996 7400. 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