Explaining ASTM A480/A480M-18 (General Requirements for Flat-Rolled Stainless)
If you have ever worked on a metals sales desk, for a service center, or for an architectural and commercial polisher, you are aware that customers provide scant information when submitting a Request for Quote (RFQ). Sometimes they are reluctant to include even the most basic information. Abstract terms and standards that need qualification stand-alone; open to a variety of interpretations. The Purchase Order is supposed to provide the contractual terms, but in the absence of the necessary, qualified information, there is confusion and misdirection, which can be costly for both parties. The proliferation of governing standards by independent organizational bodies aims to provide clarification to buyer and seller through clearly defined terms. However, these dense standards are intimidating as a layman’s reference guide. The ASTM A480/A480M is no different.
The American Society for Testing and Materials (ASTM) is an international standards organization that publishes standardized practice books that cover a wide variety of industrial topics from masonry to non-ferrous metals. ASTM A480/A480M-18 titled “Standard Specification for General Requirement for Flat-Rolled Stainless and Heat-Resisting Steel Plate, Sheet, and Strip” is self-explanatory and delineates the general requirements for flat rolled stainless. The standard explains the requirements for ordering, tracing heat numbers, and tolerance specifications. The standard also provides an in-depth resource for surface finishes.
Section 11 of ASTM A480/A480M-18 details No. 1 to No. 8 finishes with an explanatory footnote that further defines the listed surface finishes. DBM’s qualification of the surface finish is in bold:
No. 1: Hot-rolled, annealed, and pickled or descaled. Dull, non-reflecting finish. Produced only in the mill.
No. 2D: A smooth, nonreflective, cold-rolled annealed and pickled or descaled finish. Produced only in the mill.
No. 2B: A smooth, moderately reflective cold-rolled annealed and pickled or descaled produced by imparting a final light cold-rolled pass using polished rolls. Produced only in the mill.
Bright Annealed Finish: A smooth, bright, reflective finish typically produced by cold rolling followed by annealing in a protective atmosphere so as to prevent oxidation and scaling during annealing. Produced only in the mill.
No. 3: A linearly textured finish that is produced by mechanical polishing. Generally, 40-60 grit applied.
No. 4: A linearly textured finish that may is produced by mechanical polishing. A skilled operator can generally blend this finish. 60-120 grit applied for a traditional No. 4. Sanitary No. 4 is 180 grit. No. 4 used in architectural purposes is generally 120-180 grit. This finish is also known as a satin finish.
No. 6: This finish has a soft satin appearance typically produced by Tampico brushing a No. 4 finish. In practice, a No. 6 does not involve Tampico brushing but instead requires the application of 240-320 grit.
No. 7: This surface has a high degree of reflectivity. Produced by buffing a finely ground surface but the grit lines are not removed. Generally, 600 grit applied and then buffing with black compound only.
No. 8: Highly reflective finish produced by polishing and then buffing. Grit lines removed. Traditional No. 8 polished to 600 grit and then buffed with black and white compound. The faintest of grit lines may be seen. A Super Mirror No. 8 involves polishing to 600 grit, buffed with black and white compound, and then non-directional orbital polishing applied to remove any and all grit lines.
Diamond Brite Metals Quality Management Systems for flat-rolled products ensure strict compliance with ASTM A480/A480M-18. For architectural polishing or commercial polishing, please contact Diamond Brite Metals at Sales@diamondbritemetals.com.