Active Standard ASTM A918 | Developed by Subcommittee: A05.11
Book of Standards Volume: 01.06
Historical (view previous versions of standard)
This specification covers zinc-nickel alloy coatings applied by the electrolytic process to hot-rolled and cold-rolled steel sheets for applications requiring designation of the coating mass on each surface. Coating application shall be done on one or both surfaces with equal or differential coating masses and similar levels of corrosion protection, and shall have no effect on the base metal mechanical properties. The coated sheets may be available as commercial steel (CS), drawing steel (DS), deep drawing steel (DDS), extra-deep drawing steel (EDDS), structural steel (SS), high-strength low-alloy steel (HSLAS), high-strength low-alloy steel with improved formability (HSLAS-F), solution-hardened steel (SHS), or bake-hardenable steel (BHS). Coatings shall be designated accordingly, and shall undergo test methods such as weigh-strip-weigh method, and nondestructive X-ray fluorescence measurement. Individual coating designations should conform to coating mass, thickness, and composition requirements.
This abstract is a brief summary of the referenced standard. It is informational only and not an official part of the standard; the full text of the standard itself must be referred to for its use and application. ASTM does not give any warranty express or implied or make any representation that the contents of this abstract are accurate, complete or up to date.
1.1 This specification covers zinc-nickel alloy coatings applied by the electrolytic process to hot-rolled and cold-rolled steel sheet. The coating has a smooth, spangle-free surface. The zinc-nickel-coated sheet covered in this specification is produced in a range of coating masses to provide coatings that are compatible with the anticipated service life required. The coating mass varies, from very thin coatings that are usually painted to provide good service, to relatively heavy masses that provide good corrosion resistance in the bare (unpainted) condition. The composition range is from 9 to 16 % nickel, by weight, with the balance being zinc.
1.2 The product shall be coated on one or both surfaces with equal or differential coating masses on the two surfaces. Sheet coated with equal coating masses on each surface has similar levels of corrosion protection on each surface. Often, however, a higher level of corrosion protection is required on one surface than is required on the other. In these situations, one surface shall be specified with a heavier coating mass than the other. Either surface, when specified to be painted, will provide additional corrosion protection as compared to an unpainted surface.
1.3 This coating process has essentially no effect on the base metal mechanical properties, and use is permitted on any grade of hot- or cold-rolled steel sheet. The coated sheet is available as Commercial Steel (CS), Drawing Steel (DS), Deep Drawing Steel (DDS), Extra-Deep Drawing Steel (EDDS), Structural Steel (SS), High-Strength Low-Alloy Steel (HSLAS), High-Strength Low-Alloy Steel with Improved Formability (HSLAS-F), Solution-Hardened Steel (SHS), or Bake-Hardenable Steel (BHS).
1.4 The values stated in SI units are to be regarded as the standard.
2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.
A754/A754M Test Method for Coating Weight (Mass) of Metallic Coatings on Steel by X-Ray Fluorescence
A917 Specification for Steel Sheet, Coated by the Electrolytic Process for Applications Requiring Designation of the Coating Mass on Each Surface (General Requirements)
E1659 Test Methods for Coating Mass and Chemical Analysis of Zinc-Nickel Alloy Electrolytically Coated on Steel Sheet
ICS Number Code 77.140.50 (Flat steel products and semi-products)