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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Status
Historical
Publication Date
14-Mar-1991
Current Stage
Ref Project

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ASTM B600-91(1997)e1 - Standard Guide for Descaling and Cleaning Titanium and Titanium Alloy Surfaces
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NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
e1
Designation: B 600 – 91 (Reapproved 1997)
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.
e NOTE—Keywords were added editorially in December 1997.
1. Scope voltage should be controlled to prevent the occurrence of spark
discharge and subsequent pitting.
1.1 This guide covers a cleaning and descaling procedure
useful to producers, users, and fabricators of titanium and
3. Blast Cleaning
titanium alloys for the removal of ordinary shop soils, oxides,
3.1 Mechanical descaling methods such as sandblasting,
and scales resulting from heat treatment operations and foreign
shot blasting, and vapor blasting may be used to remove hot
substances present as surface contaminants.
work scales and lubricants from titanium surfaces if followed
1.2 It is not intended that these procedures be mandatory for
by thorough conditioning and cleaning as described in Section
removal of any of the indicated soils but rather serve as a guide
4.
when titanium and titanium alloys are being processed in the
3.2 The sand used for blasting should be a high-grade,
wrought, cast, or fabricated form.
washed, iron-free, silica sand. If carbon or low-alloy steel
1.3 It is the intent that these soils be removed prior to
products are sandblasted in the same facility, the sand used for
chemical milling, joining, plating, fabrication, and in any
cleaning these products should not be used on titanium surfaces
situation where foreign substances interfere with the corrosion
and a separate sand supply should be provided.
resistance, stability, and quality of the finished product.
3.3 Roughening of exposed surface areas may occur from
1.4 Acid etching may be required following cleaning when
grit or shot if cleaning of the entire surface is accomplished by
the surface has an oxygen-contaminated layer or alpha case
blasting. Partial cleaning for preserving the surface finish is to
present.
be preferred in conjunction with proper pickling procedures.
1.5 The values stated in inch-pound units are to be regarded
3.4 Blast cleaning that utilizes steel grit or sand containing
as the standard. The values in parentheses are for information
appreciable amounts of iron should be followed by acid
only.
pickling to remove any embedded steel particles on the surface
1.6 This standard does not purport to address the safety
of the titanium.
concerns, if any, associated with its use. It is the responsibility
3.5 Any abrasive or shot blast cleaning may induce residual
of the user of this standard to consult and establish appropriate
compressive stresses in the surface of the material or titanium
safety and health practices and determine the applicability of
structure. Warpage may occur in sections that are subsequently
regulatory limitations prior to use.
chemical milled or contour machined.
2. Processing Soil Removal 3.6 In most cases, blast cleaning is not intended to eliminate
pickling procedures completely. Abrasives will not remove
2.1 It is recommended that grease, oil, and lubricants
surface layers contaminated with interstitial elements such as
employed in machining, forming, and fabricating operations on
carbon, oxygen, and nitrogen. When these elements are present
titanium and titanium alloys be removed by alkaline or
in excessive amounts, they are preferably removed by con-
emulsion soak-type cleaners and electrolytic alkaline cleaning
trolled acid pickling in accordance with 4.3.
systems. In the electrolytic system the work may be either
anodic or cathodic polarity. Removal of these soils is recom-
4. Pickling and Descaling
mended prior to heat treatment or application of acid treatment
4.1 Recommended post treatment of shot or abrasive blasted
designated in 4.2. When electrolytic systems are employed, the
titanium surfaces may include acid pickling as described in
4.3.2, to ensure complete removal of metallic iron, oxide, scale,
This recommended practice is under the jurisdiction of ASTM Committee B-10
and other surface contaminants. If the product is to be chemical
on Reactive and Refractory Metals and Alloysand is the direct responsibility of
milled for the removal of the oxygen-contaminated layer, salt
Subcommittee B10.01 on Titanium.
Current edition approved March 15, 1991. Published May 1991. Originally bath conditioning may be required to avoid selectively etched
published as B 600 – 74. Last previous edition B 600 – 74 (1985).
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
B 600
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
structures to avoid any thermally induced distortion.
4.2.4 Oxides and heat tints developed below 1100°F
NOTE 5
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