BS ISO 4997:2015 pdf download – Cold-reduced carbon steel sheet of structural quality
5.7 Surface quality
5.7.1 General
The products are supplied according to either surface quality A or B.
5.7.2 Surface quality A (unexposed)
Imperfections, such as pores, slight imperfections, small marks, minor scratches, and slight colouring,which do not affect the formability or the application of surface coatings, are permitted.
5.7.3 Surface quality B (exposed) The better of the two surfaces shall be free of imperfections, which might affect the uniform appearance of quality paint or an electrolytic coating (see 5.9). The other surface shall at least conform to surface quality A. In the case of delivery of coil and slit coil, the percentage of defects can be greater than in the case of delivery in sheet or cut lengths. The purchaser should take this into account, and the percentage of admissible surface defects can be agreed at the time of the enquiry and order. Unless otherwise agreed, a single surface of the product shall comply with the specified requirements.
The other surface shall be such that, during subsequent treatment, it does not have a deleterious effect on the better surface.
5.8 Surface finish
5.8.1 Cold-reduced steel sheet is normally produced with a matte finish, dull in appearance, which is suitable for ordinary decorative painting but is not recommended for electroplating. 5.8.2 When cold-reduced steel sheet is deformed during fabrication, localized areas can roughen to some degree, and such affected portions of the part might require hand-finishing to prepare the surface for the intended application.
5.8.3 By agreement at the time of the enquiry and order, ranges for surface roughness can be specified for specific end uses. 5.9 Suitability for surface coating The products can be required for metallic coating by the hot dip coating or electrolytic coating process, or organic coating or other coating. When such a coating is intended, it shall be specified at the time of ordering. 5.10 Oiling As a deterrent to rusting, a coating of oil is usually applied to the product. The oil is not intended as a drawing or forming lubricant and shall be easily removed using degreasing chemicals. The product can be ordered not-oiled, if required, in which case, the supplier has limited responsibility if oxidation occurs.
6 Dimensional and shape tolerances Dimensional and shape tolerances applicable to cold-reduced steel sheet shall be as given in ISO 16162.
7 Tensile-test sampling One representative sample for the tensile test, as required in Table 4, shall be taken from each lot of sheet for shipment.
8 Tensile test
The tensile test shall be carried out in accordance with ISO 6892-1. Transverse test pieces shall be taken midway between the centre and the edge of the sheet as rolled.
9 Retests
9.1 Machining and flaws If any test piece shows defective machining or defective flaws, it shall be discarded and another test piece shall be substituted.
9.2 Elongation If the percentage elongation of any test piece is less than that specified in Table 4, and if any part of the fracture is outside the middle half of the gauge length as scribed before the test, the test shall be discarded and a retest shall be carried out.
9.3 Additional tests If a test does not give the specified results, two additional tests shall be carried out at random on the same lot. Both retests shall conform to the requirements of this International Standard; otherwise, the lot shall be rejected. 10 Resubmission
10.1 The manufacturer can resubmit, for acceptance, the products that have been rejected during earlier inspection because of unsatisfactory properties, after the rejected products have been subjected to a suitable treatment (selection, heat treatment, etc.) which, on request, will be indicated to the purchaser. In this case, tests shall be carried out as if they applied to a new lot.
10.2 The manufacturer has the right to present the rejected products for fresh examination for compliance with the requirements for another grade.