ISO 3574:2012 pdf download – Cold-reduced carbon steel sheet of commercial and drawing qualities
3.2 skin pass
light cold-rolling of hot-rolled steel sheet or hot-rolled descaled steel
Note 1 to entry: The purpose of the skin pass is to produce a higher degree of surface smoothness and thereby improve the surface appearance. The skin pass also temporarily minimizes the occurrence of a surface condition known as stretcher strain (Luder’s Lines) or fluting during the fabrication of finished parts. The skin pass also controls and improves flatness. Some increase in hardness and loss of ductility will result from skin passing.
3.3 camber
greatest deviation of a side edge from a straight line, the measurement being taken on the concave side with a straightedge
3.4 out-of-square
greatest deviation of an end edge from a straight line at right angles to a side and touching one corner, the measurement being taken as described in ISO 16162, or measurable as one-half the difference between the diagonals of the cut-length sheet
3.5 stabilized interstitial free steel
extra-low-carbon steel in which all interstitial elements are combined with titanium and/or equivalent elements
5.1 Chemical composition
The chemical composition (heat analysis) shall not exceed the values given in Tables 1 and 2. On request, a report of the heat analysis shall be made to the purchaser. Each of the elements listed in Table 2 shall be included in the report of the heat analysis. When the amount of copper, nickel, chromium or molybdenum present is less that 0,02 %, the analysis result may be reported as “< 0,02 %”. A verification analysis may be made by the purchaser to verify the specified analysis of the product and shall take into consideration any normal heterogeneity. Non-killed steels (such as rimmed or capped steels) are not technologically suited to product analysis. For killed steels, the sampling method and deviation limits shall be agreed upon between the interested parties at the time of ordering. The product analysis tolerances are shown in Table 3. The processes used in making the steel and in manufacturing zinc-coated sheet are left to the discretion of the manufacturer. When requested, the purchaser shall be informed of the steel-making process used.
5.6 Strain ageing
Cold-reduced sheet, in qualities CR1, CR2, and CR3 supplied in the skin-passed condition, tends to strain age and this may lead to the following:
a) surface markings from stretcher strains (Lüders lines) or fluting when the steel is formed;
b) deterioration in ductility.
Because of these factors, it is essential that the period between final processing at the mill and fabrication be kept to a minimum. Rotation of stock, by using the oldest material first, is important. Stocking of such steels for extended periods of time should be avoided; for optimum performance, the period should not exceed 6 weeks. For skin-passed sheet in qualities CR1, CR2 and CR3, and with due regard to the foregoing precautions, reasonable freedom can be achieved by effective roller leveling immediately prior to fabrication at the purchaser’s plant. Freedom from stretcher strain and fluting for a period of six months can be achieved by the supply of skin-passed non-ageing steels. Grades CR4 or CR5 shall be specified in such cases where Lüders lines are not acceptable and where roller leveling is not possible.