ASTM B600-91(2002)
(Guide)Standard Guide for Descaling and Cleaning Titanium and Titanium Alloy Surfaces
Standard Guide for Descaling and Cleaning Titanium and Titanium Alloy Surfaces
SCOPE
1.1 This guide covers a cleaning and descaling procedure useful to producers, users, and fabricators of titanium and titanium alloys for the removal of ordinary shop soils, oxides, and scales resulting from heat treatment operations and foreign substances present as surface contaminants.
1.2 It is not intended that these procedures be mandatory for removal of any of the indicated soils but rather serve as a guide when titanium and titanium alloys are being processed in the wrought, cast, or fabricated form.
1.3 It is the intent that these soils be removed prior to chemical milling, joining, plating, fabrication, and in any situation where foreign substances interfere with the corrosion resistance, stability, and quality of the finished product.
1.4 Acid etching may be required following cleaning when the surface has an oxygen-contaminated layer or alpha case present.
1.5 The values stated in inch-pound units are to be regarded as the standard. The values in parentheses are for information only.
1.6 This standard does not purport to address the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to consult and establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:B600–91(Reapproved 2002)
Standard Guide for
Descaling and Cleaning Titanium and Titanium Alloy
Surfaces
This standard is issued under the fixed designation B 600; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope designated in 4.2.When electrolytic systems are employed, the
voltage should be controlled to prevent the occurrence of spark
1.1 This guide covers a cleaning and descaling procedure
discharge and subsequent pitting.
useful to producers, users, and fabricators of titanium and
titanium alloys for the removal of ordinary shop soils, oxides,
3. Blast Cleaning
and scales resulting from heat treatment operations and foreign
3.1 Mechanical descaling methods such as sandblasting,
substances present as surface contaminants.
shot blasting, and vapor blasting may be used to remove hot
1.2 It is not intended that these procedures be mandatory for
work scales and lubricants from titanium surfaces if followed
removal of any of the indicated soils but rather serve as a guide
by thorough conditioning and cleaning as described in Section
when titanium and titanium alloys are being processed in the
4.
wrought, cast, or fabricated form.
3.2 The sand used for blasting should be a high-grade,
1.3 It is the intent that these soils be removed prior to
washed, iron-free, silica sand. If carbon or low-alloy steel
chemical milling, joining, plating, fabrication, and in any
products are sandblasted in the same facility, the sand used for
situation where foreign substances interfere with the corrosion
cleaningtheseproductsshouldnotbeusedontitaniumsurfaces
resistance, stability, and quality of the finished product.
and a separate sand supply should be provided.
1.4 Acid etching may be required following cleaning when
3.3 Roughening of exposed surface areas may occur from
the surface has an oxygen-contaminated layer or alpha case
grit or shot if cleaning of the entire surface is accomplished by
present.
blasting. Partial cleaning for preserving the surface finish is to
1.5 The values stated in inch-pound units are to be regarded
be preferred in conjunction with proper pickling procedures.
as the standard. The values in parentheses are for information
3.4 Blast cleaning that utilizes steel grit or sand containing
only.
appreciable amounts of iron should be followed by acid
1.6 This standard does not purport to address the safety
pickling to remove any embedded steel particles on the surface
concerns, if any, associated with its use. It is the responsibility
of the titanium.
of the user of this standard to consult and establish appropriate
3.5 Any abrasive or shot blast cleaning may induce residual
safety and health practices and determine the applicability of
compressive stresses in the surface of the material or titanium
regulatory limitations prior to use.
structure. Warpage may occur in sections that are subsequently
2. Processing Soil Removal chemical milled or contour machined.
3.6 In most cases, blast cleaning is not intended to eliminate
2.1 It is recommended that grease, oil, and lubricants
pickling procedures completely. Abrasives will not remove
employedinmachining,forming,andfabricatingoperationson
surface layers contaminated with interstitial elements such as
titanium and titanium alloys be removed by alkaline or
carbon, oxygen, and nitrogen.When these elements are present
emulsion soak-type cleaners and electrolytic alkaline cleaning
in excessive amounts, they are preferably removed by con-
systems. In the electrolytic system the work may be either
trolled acid pickling in accordance with 4.3.
anodic or cathodic polarity. Removal of these soils is recom-
mended prior to heat treatment or application of acid treatment
4. Pickling and Descaling
4.1 Recommendedposttreatmentofshotorabrasiveblasted
This guide is under the jurisdiction ofASTM Committee B10 on Reactive and titanium surfaces may include acid pickling as described in
Refractory Metals and Alloys and is the direct responsibility of Subcommittee
4.3.2,toensurecompleteremovalofmetalliciron,oxide,scale,
B10.01 on Titanium.
andothersurfacecontaminants.Iftheproductistobechemical
Current edition approved March 15, 1991. Published May 1991. Originally
milled for the removal of the oxygen-contaminated layer, salt
published as B 600 – 74. Last previous edition B 600 – 74 (1985).
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
B600
bath conditioning may be required to avoid selectively etched mended that the acid solution be maintained at 150°F (66°C)
surfaces if configuration interferes with uniform blasting. and a concentration of 10 to 40 volume % of sulfuric acid
4.2 Scale and lubricant residues developed on mill, foundry, (95 % solution by weight). Final brightening may be accom-
forged, or fabricated titanium products usually require condi- plished by a short immersion in the acid solution of 4.3.2.
tioning by one of the following commercial methods prior to
4.3.2 Material that has been mechanically abraded in accor-
final pickling as described in 4.3.2 to produce a completely
dance with 3.1 or chemically conditioned in accordance with
scale-free surface.
4.2.1, 4.2.2, or 4.2.3 may be finish cleaned by immersion in an
4.2.1 Proprietary solutions of caustic-based compounds in
acid solution composed of 10 to 30 volume % (150 to 450 g/L)
tap water in accordance with the manufacturer’s recommenda-
of nitric acid (70 %) and 1 to 3 volume % (12 to 36 g/L) of
tion.
hydrofluoric acid (60 % at 120°F (49°C)), maintaining a ratio
4.2.2 Molten alkaline-based salt baths operating at 750 to
of 10 parts nitric acid to 1 part hydrofluoric acid.
850°F (399 to 454°C) in accordance with prescribed proce-
NOTE 4—Hot-formed or heat-treated titanium fabrications or assem-
dures.
blies that have a mixed surface contamination consisting of graphite or
4.2.3 Molten alkaline-based salt baths operating at 400°F
molybdenum disulfide with titanium oxides should be conditioned in a
(204°C) in accordance with prescribed procedures.
molten salt bath. The 400°F (204°C) temperature is preferred for these
4.2.4 Oxides and heat tints developed below 1100°F
structures to
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