Various coding systems are used to describe
finishes produced in the rolling mill and by subsequent polishing
and other treatments.
Euronorm 88-86 parts 2 and 3 currently lists codings used
in DIN 17440 and ASTM A480. The tables of finishes give approximate
comparisions with codings in BS 1449 part 2 and JIS G4305.
Additional finishes include:
Rigidized using embossed rolls.
Patterned using engraved rolls with 'leather', 'linen' or
'mosaic' surfaces.
Coloured by chemical/electrochemical treatments.
Coloured by resin/plastic films applied by continuous roll
coating.
Coloured by vapour deposition.
Electropolishing.
Designated Surface Finishes:
Approx Similar Finish
Types
of
Treatment
Appearance
and approximate Surface roughness (microns)
DIN
17440
ASTM
A480
BS
1449
JIS
G4305
a1
As HR
Some use for heat resistance. Scaled,
but requires full machining or DS
for corrosive service.
b,Ic
0
HR,HT
Scaled, as above.
c,IIa
1
1
HR,HT,DS
Metallic, rough (4-7), used where
smoothness and appearance unimportant.
f,IIIa
TR
HR,HT,DS,CR
or BA,CR
Bright, much smoother than c. For
uses requiring higher strength.
h,IIIb
2D
2D
2D
DS,CR,HT,DS
Uniform matt, smoother than c(0.4-1).
Similar finish from unpolished rolls.
Helps retain forming lubricants.Polishable.
m,IIId
BA
2A
BA
DS,CR,BA
Bright, highly reflective (0.05-0.1).
Sometimes lightly rolled.
n,IIIc
2B
2B
2B
DS,CR,HT,DS
Light CR
Matt,brighter&smoother than
h. General purpose, highly polishable (0.1-0.5).
Uniform
straight grained finish (0.4- 1.5). Belt
polished or abraded with
180-220 mesh grit.
(0,IV)
4
4
4
Dull
Ground/
Polished
Brighter
than 3A,3B (0.2- 1.5). Not highly
reflective.Finishing grit sizes
vary:120-180 ASTM, 180-240 BS, 150-180
JIS. General purpose finish.
5
Fine Ground/
Polished
Clean-cut
grinding/polishing to a surface
roughness, Ra, 0.5 microns maximum.
q
6
Brushed
Satin,
lower lustre appearance obtained by abrasive
brushing of 4,2B,n finishes.
(p,V)
7
7
Bright
Buffed
Bright,
highly reflective finish from mop buffing
of 2A,2B or finely ground and polished
surfaces (around 0.1).
(p,V)
8
8
Bright
Polished
Bright
reflective mirror finish. Pro- gressive
polishing using finer grits and
fine polishing compounds.
240
Polishing
Finished
using 240 mesh grit abrasives
320
Polishing
Finished using 320 mesh
grit abrasives
400
Polishing
Finished using 400 mesh
grit abrasives
HR = Hot rolled.
CR = Cold rolled.
HT = Heat treated, solution annealed, quench annealed or softened.
DS = Descaled chemically or mechanically; or finish-pickled.
BA = Bright annealed without scaling or oxidation at the corresponding
HT temperature
