The surface finish requirements of material under ASTM: Specifications A167, A176, A240/A240M, A263, A264, A265, A666, A693, A793, and A895 are given in
ASTM A480/A480M-05 Standard Specification for General Requirements for Flat-Rolled Stainless and Heat-Resisting Steel Plate, Sheet, and Strip.
"M" indicates a
Metric specification (SI units).
However, I don't have the 2005 revision of
ASTM A480/A480M; my older copy has the finishes described and shown (with photos) at
"3" possibly corresponds to the previous No. 3 finish: Intermediate polished finish, one or both sides.
From SSINA:
"No. 3 Finish is characterized by short, relatively coarse, parallel polishing lines, which extend uniformly along the length of the coil. It is obtained by either mechanically polishing with gradually finer abrasives or by passing the coil through special rolls, which press a pattern into the surface that simulates the appearance of mechanical abrasion. It is a moderately reflective finish. When mechanically polishing, 50 or 80 grit abrasives are typically used initially and the final finish is typically achieved with 100 or 120 grit abrasives. The surface roughness is typically Ra 40 micro-inches or less. If a fabricator needs to blend in welds or do other refinishing, the resulting polishing lines are usually longer than on product polished by a producer or toll-polishing house."
"H" possibly indicates work
Hardened; i.e., cold rolled, as in the EuroNorm standard
EN10088/2. See "Surface Finishes" (1 page) at or
"Guide to Stainless Steel Finishes" (24 pages) at
No equivalent to H-3 or MH-3 is given.