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ISO 4969:2015 pdf free

ISO 4969:2015 pdf free.Steel一Etching method for macroscopic examination
The position and number of sampling shall be determined according to the requirements of the product standard, specification, contract or order. In the absence of any special requirements, sampling must be planned according to the details of the manufacturing process and the grade being evaluated.
The macroetching test, as applied to the inspection of steel products of this method, is carried out on slices, usually 13 mm to 25 mm in thickness. Disks or specimens are usually cut to reveal a transverse surface, but the requirements of the specification, contract, or order can include the preparation and examination of a longitudinal surface. In most cases, a longitudinally-oriented macroetching disc is taken with the plane to be etched along the centre line of the wrought product and it includes both outside surfaces with a length in the longitudinal direction, usually 1,5 times greater than the thickness or diameter.
In the case of large specimens which cannot be immersed, such as ingot sections, swabbing might be the only practical method of macroetching. Saturate a large wad of cotton held in stainless steel or nickel tongs with the etchant and sweep over the surface of the specimen. An effort should be made to wet the entire surface as soon as possible. After the initial wetting, keep the swab saturated with solution and frequently sweep over the surface of the specimen to renew the solution. Ensure a uniform and constant distribution of the reagent over the surface. When the structure has been suitably developed, rinse the specimen, either with a swab saturated with water, or better still, by pouring water over the specimen.
After rinsing with water, blow the specimen dry with compressed air.
When the etching is considered satisfactory, remove the test piece from the bath taking great care not to touch the etched surface, wash it in running water, brush it carefully (with a non-metallic brush) to remove any residue from the etch, and then dry it. When desmutting is required, dip the specimen into a second solution, such as 3 % to 5 % sodium carbonate (Na2CO3) or 10 % to 15 % nitric acid solutions.
The type of etchant, etching time and etching temperature are chosen according to the steel grade, as described in Table 1 and Table 2.
For each type of etchant, the time of application varies with the test temperature, the steel grade and even the type of examination. It is preferable that the treatment be entrusted to an experienced operator who will supervise the process and end it when he/she considers the etch to be adequate.
Generally, over-etching can often lead to misinterpretation. The times given in individual tabulations are only intended as guides. The actual time to develop a structure properly can be quite different from the one suggested.ISO 4969 pdf download.

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