Machinery's Handbook, 31st Edition
1450 SHEET METAL MILL FINISHES Coatings on Aluminum and of Other Nonconductive Coatings on Nonmagnetic Basis Metals with Eddy Current Instruments”: This nondestructive method determines coating thickness using the lift-off effect of a probe coil, which contacts the coating and generates measurable eddy currents in the aluminum substrate; 2) ASTM B137, “Test Method for Measurement of Weight of Coating Mass per Unit Area on Anodically Coated Alumi- num”: This test involves weighing a small sample of known surface area on an analytical balance, dissolving the coating in a solution that does not attack aluminum, and then re- weighing the specimen and comparing weights. Surface Finishes of Stainless Steel Sheet.— Finishes for stainless steel include standard mill and polished, proprietary, electropolished, blasted, rolled, textured, colored, or etched, or any combination of these. Specific finishes for stainless steel sheet and strip products are defined in ASTM A480/ ASTM A480M, “Standard Specification for General Requirements for Flat-Rolled Stain - less and Heat-Resisting Steel Plate, Sheet, and Strip” (see Table 19 ). These finishes are identified by a system of numbers and letters: unpolished or “mill” finishes are No. 1, No. 2D, and BA for bright annealed (usually 2BA); polished finishes are No. 3, No. 4, No. 6, No. 7, and No. 8. Temper-rolled (TR) finishes are used when strong mechanical properties are needed. Also specified are additional architectural finishes, which may be described as No. 5 and form a separate category, as there are numerous techniques and finish varia - tions available worldwide. Other finishes, such as embossing, coining, and special rolled finishes, also are applied mechanically; non-mechanical options include coloring and etching.
Table 19. Standard Mechanical Finishes for Stainless Steel Sheet, ASTM A480/A480M
Finish Designation
DEFINITION
NOTES
Unpolished Finishes (Mill Finishes) This is a dull, nonreflective finish.
No. 1
Hot-rolled, annealed and pickled, and descaled Cold-rolled, dull finish
No. 2D
A smooth, nonreflective, cold-rolled, annealed, and pickled or descaled finish. This nondirectional finish is effective in retaining lubricants in deep drawing applications. A smooth, moderately reflective, cold-rolled and annealed and pickled or descaled finish typically produced with a final, light, cold-rolled pass using polished rolls. This general-purpose finish is more readily polished than No. 1 or No. 2D. Product with No. 2B finish is normally supplied in annealed plus lightly cold-rolled condition, unless a tensile-rolled product is specified. This smooth, bright, reflective finish is usually produced by cold-rolling, followed by annealing in a protective atmosphere to prevent oxidation and scaling during annealing. Polished Finishes A linearly textured finish, produced by either mechanical polishing or rolling, with surface roughness average generally up to 40 µ in. or 1.016 µ m Ra. Surface roughness differs with various instruments, laboratories, and skilled operators, who may blend this finish. There can be overlap in surface roughness measurements for No. 3 and No. 4 finishes. A linearly textured finish produced by either mechanical polishing or rolling, with surface roughness average generally up to 25 µ in. or 0.635 µ m Ra. Surface roughness differs with various instruments, laboratories, and skilled operators, who may blend this finish. There can be overlap in surface roughness measurements for No. 3 and No. 4 finishes. Has a soft, satin appearance, typically produced by Tampico brushing a No. 4 finished sheet. Has a high degree of reflectivity, produced by buffing a finely ground surface, but grit lines are not removed. Chiefly used for architectural or ornamental purposes.
No. 2B
Cold-rolled, bright finish
BA (bright annealed)
Bright, cold-rolled finish, retained by final annealing in a controlled atmosphere furnace Intermediate polished finish, one or both sides
No. 3
No. 4
General purpose polished finish, one or both sides
No. 6
Dull, satin finish, Tampico brushed, one or both sides
No. 7
High-luster finish
Copyright 2020, Industrial Press, Inc.
ebooks.industrialpress.com
Made with FlippingBook - Share PDF online