Strip Finishes

Hot-rolled stainless steel strip is a semifinished product obtained from the hot rolling of slabs or billets and is produced for conversion by cold rolling. Cold-rolled stainless steel strip is manufactured from hot-rolled, annealed, and pickled strip by cold rolling on polished rolls. Depending on the thickness desired, the cold rolling requires various numbers of passes through the mill to effect the necessary reduction and to secure the desired surface characteristics and mechanical properties. Only three rolled (unpolished) finishes (No. 1, No. 2, and bright annealed) and one polished finish (mill buffed) are commonly supplied on stainless steel strip.

No. 1 finish is produced by cold rolling, annealing, and pickling. Appearance varies from dull gray matte to fairly reflective, depending largely on stainless steel type. This finish is used for severely drawn or formed parts, as well as for applications where the brighter No. 2 finish is not required, such as parts to be used at high temperatures. No. 1 finish for strip approximates No. 2D finish for sheet in corresponding chromium-nickel or chromium-nickel-manganese types.

No. 2 finish is produced by the same treatment used for No. 1 finish, followed by a final light cold-rolling pass, which generally is done using highly polished rolls. This final pass produces a smoother and more reflective surface, the appearance of which varies with stainless steel type. No. 2 finish for strip is a general-purpose finish widely used for household appliances, automotive trim, tableware, and utensils. No. 2 finish for strip approximates No. 2B finish for sheet in corresponding chromium-nickel or chromium-nickel-manganese stainless steels.

Bright annealed finish is a bright, cold-rolled, highly reflective finish retained by final annealing in a controlled-atmosphere furnace. The purpose of atmosphere control is to prevent scaling or oxidation during annealing. The atmosphere usually consists of either dry hydrogen or dissociated ammonia. Bright annealed strip is used most extensively for automotive trim.

Mill-buffed finish is a highly reflective finish obtained by subjecting either No. 2 or bright annealed coiled strip to a continuous buffing pass. The purpose of mill buffing is to provide a finish uniform in color and reflectivity. It also can provide a surface receptive to chromium plating. This type of finish is used chiefly for automotive trim, household trim, tableware, utensils, fire extinguishers, and plumbing fixtures.

Grade Limitations. Not all of the standard compositions of stainless steel strip are available in each of the standard mill finishes. Surface finishes of these products depend on end use rather than any restriction imposed by the supplier. Table 4 lists the finishes most often applied to sheet and strip of a number of standard grades of austenitic, martensitic, and ferritic steels.

Table 4 Mill finishes available on stainless steel sheet and strip

See text for explanation of numerical designations of finishes

Table 4 Mill finishes available on stainless steel sheet and strip

See text for explanation of numerical designations of finishes

Type

Sheet

Strip

Unpolished

Polished

Austenitic steels(a)

201

2D, 2B

(b)

1, 2

202

2D, 2B

3, 4

1, 2

301

2D, 2B

(b)

1, 2

302

2D, 2B

3, 4, 6,7

1, 2

302B

2D

(b)

304

2D, 2B

3, 4, 6,7

1, 2

304L

2D, 2B

4

1, 2

305

2D, 2B

(b)

1, 2

309, 309S

2D

(b)

1, 2

310

2D

(b)

1, 2

316

2D, 2B

4

1, 2

316L

2D, 2B

(b)

1, 2

321

2D, 2B

(b)

1, 2

347

2D, 2B

(b)

1, 2

348

2D, 2B

(b)

1, 2

Martensitic steels

403

2D, 2B

(b)

1, 2

410

2D, 2B

(b)

1, 2

420

(c)

(c)

1, 2

440A, B, and C

(c)

(c)

(d)

Ferritic steels(a)

430

2D, 2B

3, 4

1, 2

446

2D, 2B

(b)

1, 2

(a) All grades listed, in both sheet and strip form, are regularly available in the smooth rolled and bright annealed condition.

(b) Usually not polished.

(c) Not available in sheet form.

(d) Material available in strip form on special order only; finish negotiated with supplier

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