ASTM F288-96(2019)

Standard Specification for Tungsten Wire for Electron Devices and Lamps

ABSTRACT
This specification covers three types of drawn pure and thoriated tungsten wire suitable for fabrication into parts for electron tubes, lamps, and other electron devices, and one type of rod for metal-to-glass sealing (grid wire is excepted): Type 1A, Type 1B, Type 2A, and Type 2B. Types 1A and 1B are designated as UNS R07005; Type 2A is designated as UNS R07911; and Type 2B is designated as UNS R07912. The wire and rod shall conform to the prescribed chemical requirements for thoria and tungsten and to the specified physical properties such as tensile strength, ductility, and surface defects. The weight/diameter conversion formulas are given. Wires shall be furnished in the following specified finishes: Finish 1, Finish 2, Finish 3, Finish 4, Finish 5, Finish 6, and Finish 7. The material shall be smooth, free of twists, bends, kinks, curls, and as free of dents, swaging marks, scratches, die marks, laps, seams, splits, slivers, inclusions, bumps, pits, grooves, cracks, and other physical defects Unless black finish is specified, all types of wire shall have a clean finish, free of graphite, grease, oil, and lubricants. Wire for hooks, supports, springs, anchors, and mesh shall have a bright smooth surface free of cracks holes, or craters. The requirements for straightness, and coiling and spooling are detailed as well. The following analysis and tests shall be performed: chemical analysis, tensile test, ductility test, visual inspection, dimensional measurements, and examination for surface flaws.
SCOPE
1.1 This specification covers three types of drawn wire suitable for fabrication into parts for electron tubes, lamps, and other devices; and one type of rod for metal-to-glass sealing (grid wire is excepted):  
1.1.1 Type 1A—Commercially pure nonsag wire (Note 2 and Note 3).  
1.1.2 Type 1B—Commercially pure rod suitable for metal-to-glass sealing.  
1.1.3 Type 2A—Thoriated filament wire containing 1 % thoria.  
1.1.4 Type 2B—Thoriated filament wire containing 2 % thoria.  
1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.  
1.3 Types 1A and 1B are designated as UNS R07005. Type 2A is designated as UNS R07911. Type 2B is designated as UNS R07912.  
1.4 The following precautionary caveat pertains only to the Chemical Analysis, Section 12 of this specification: This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
Note 1: A dimensional measurement method for testing nonsag tungsten wire above 0.030 in. (0.76 mm) in diameter is provided in Test Method F269.
Note 2: Acceptance of nonsag wire characteristics for particular applications of size shall be by agreement between producer and consumer based on either a flashed microstructure as shown by photomicrographs, or on dimensional measurement limits determined in accordance with Test Method F269.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-Mar-2019
• ICS: 29.060.10 - Wires
• Technical Committee: F01 - Electronics
• Drafting Committee: F01.03 - Metallic Materials, Wire Bonding, and Flip Chip

Relations

• Replaces: ASTM F288-96(2014) - Standard Specification for Tungsten Wire for Electron Devices and Lamps
• Effective Date: 01-Apr-2019
• Refers: ASTM F205-94(2020) - Standard Test Method for Measuring Diameter of Fine Wire by Weighing (Withdrawn 2023)
• Effective Date: 01-May-2020
• Refers: ASTM F269-60(2019) - Standard Test Method for Sag of Tungsten Wire
• Effective Date: 01-Apr-2019
• Refers: ASTM F204-76(2018) - Standard Test Method for Surface Flaws in Tungsten Seal Rod and Wire
• Effective Date: 01-Mar-2018
• Refers: ASTM F219-96(2018) - Standard Test Methods of Testing Fine Round and Flat Wire for Electron Devices and Lamps (Withdrawn 2023)
• Effective Date: 01-Mar-2018
• Refers: ASTM F205-94(2015) - Standard Test Method for Measuring Diameter of Fine Wire by Weighing
• Effective Date: 01-Jul-2015
• Refers: ASTM F269-60(2014) - Standard Test Method for Sag of Tungsten Wire
• Effective Date: 01-Jun-2014
• Refers: ASTM F204-76(2013) - Standard Test Method for Surface Flaws in Tungsten Seal Rod and Wire
• Effective Date: 01-May-2013
• Refers: ASTM F219-96(2013) - Standard Test Methods of Testing Fine Round and Flat Wire for Electron Devices and Lamps
• Effective Date: 01-May-2013
• Refers: ASTM F16-12 - Standard Test Methods for Measuring Diameter or Thickness of Wire and Ribbon for Electronic Devices and Lamps
• Effective Date: 01-Feb-2012
• Refers: ASTM F205-94(2010)e1 - Standard Test Method for Measuring Diameter of Fine Wire by Weighing
• Effective Date: 01-Dec-2010
• Refers: ASTM F204-76(2009) - Standard Test Method for Surface Flaws in Tungsten Seal Rod and Wire
• Effective Date: 01-May-2009
• Refers: ASTM F219-96(2009) - Standard Test Methods of Testing Fine Round and Flat Wire for Electron Devices and Lamps
• Effective Date: 01-May-2009
• Refers: ASTM F269-60(2009) - Standard Test Method for Sag of Tungsten Wire
• Effective Date: 01-May-2009
• Refers: ASTM F16-67(2006) - Standard Test Methods for Measuring Diameter or Thickness of Wire and Ribbon for Electronic Devices and Lamps
• Effective Date: 01-Feb-2006

Overview

ASTM F288-96(2019), titled Standard Specification for Tungsten Wire for Electron Devices and Lamps, provides comprehensive requirements for the composition, physical properties, finishes, and testing of drawn pure and thoriated tungsten wire and rod. These materials are primarily intended for applications in electron tubes, lamps, and metal-to-glass sealing in various electron devices, except grid wire. This standard is an essential reference for manufacturers and users to ensure product quality, reliability, and compliance within the electron device and lighting industries.

Key Topics

• Material Types and Designations

  • Type 1A: Commercially pure, nonsag tungsten wire (UNS R07005)
  • Type 1B: Commercially pure rod for metal-to-glass sealing (UNS R07005)
  • Type 2A: Thoriated tungsten wire with 1% thoria (UNS R07911)
  • Type 2B: Thoriated tungsten wire with 2% thoria (UNS R07912)

• Chemical and Physical Requirements

  • Detailed chemical composition limitations for tungsten and thoria content
  • Physical properties including tensile strength and ductility for various wire sizes
  • Surface quality criteria such as freedom from defects, scratches, and contamination

• Finish and Appearance

  • Seven prescribed finishes, ranging from black as-drawn to electropolished, ensuring suitability for diverse applications
  • Requirements for cleanliness and absence of foreign materials or surface defects

• Dimensions and Tolerances

  • Specified dimensional tolerances, out-of-roundness limits, and weight/diameter conversion formulas
  • Straightness, coiling, and spooling requirements for wire handling and processing

• Testing and Inspection

  • Mandatory tests include chemical analysis, tensile and ductility tests, visual inspection, and checks for surface flaws
  • Procedures for dimensional measurements and surface flaw examination

• Order and Packaging Information

  • Guidelines for specifying length, type, finish, size, and relevant specification numbers when ordering
  • Requirements for marking, packaging, and shipping to maintain product integrity

Applications

The wire and rod products covered under ASTM F288-96(2019) are widely used in:

• Electron Tubes and Electron Devices: As filament, support, and grid components requiring high purity and precise mechanical properties.
• Lamps: In incandescent lamps, the specification ensures the durability and stability of tungsten filaments.
• Metal-to-Glass Seals: The rod (Type 1B) is specifically formulated for reliable sealing between metals and glass, a critical function in vacuum-tube technology.
• Other Industrial Uses: Including hooks, supports, springs, anchors, and mesh in high-reliability contexts where surface quality and mechanical strength are paramount.

Related Standards

ASTM F288-96(2019) references and aligns with several other industrial and military standards for testing and inspection, such as:

• ASTM F16: Test Methods for Measuring Diameter or Thickness of Wire and Ribbon for Electronic Devices and Lamps
• ASTM F204: Test Method for Surface Flaws in Tungsten Seal Rod and Wire
• ASTM F205: Test Method for Measuring Diameter of Fine Wire by Weighing
• ASTM F219: Test Methods for Testing Fine Round and Flat Wire for Electron Devices and Lamps
• ASTM F269: Test Method for Sag of Tungsten Wire
• Military Standards: MIL-STD-105 for sampling procedures and MIL-STD-129 for shipment marking

Practical Value

By adhering to ASTM F288-96(2019), manufacturers and buyers ensure consistent tungsten wire quality, proper performance in sensitive electronic and lighting devices, and reliable metal-to-glass sealing. This standard also facilitates global trade and product acceptance by conforming to international standardization principles as established by the WTO Technical Barriers to Trade (TBT) Committee.

Keywords: ASTM F288, tungsten wire specification, thoriated tungsten wire, tungsten rod, electron device materials, lamp filament standards, UNS R07005, UNS R07911, UNS R07912, metal-to-glass seal, electron tube materials.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation:F288 −96 (Reapproved 2019)
Standard Specification for
Tungsten Wire for Electron Devices and Lamps
ThisstandardisissuedunderthefixeddesignationF288;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope 1.5 This international standard was developed in accor-
dance with internationally recognized principles on standard-
1.1 This specification covers three types of drawn wire
ization established in the Decision on Principles for the
suitableforfabricationintopartsforelectrontubes,lamps,and
Development of International Standards, Guides and Recom-
other devices; and one type of rod for metal-to-glass sealing
mendations issued by the World Trade Organization Technical
(grid wire is excepted):
Barriers to Trade (TBT) Committee.
1.1.1 Type 1A—Commerciallypurenonsagwire(Note2and
Note 3).
2. Referenced Documents
1.1.2 Type 1B—Commercially pure rod suitable for metal-
to-glass sealing. 2.1 ASTM Standards:
1.1.3 Type 2A—Thoriated filament wire containing 1% F16Test Methods for Measuring Diameter or Thickness of
thoria. Wire and Ribbon for Electronic Devices and Lamps
1.1.4 Type 2B—Thoriated filament wire containing 2% F204Test Method for Surface Flaws in Tungsten Seal Rod
thoria. and Wire
F205Test Method for Measuring Diameter of Fine Wire by
1.2 Thevaluesstatedininch-poundunitsaretoberegarded
Weighing
as standard. The values given in parentheses are mathematical
F219Test Methods ofTesting Fine Round and FlatWire for
conversions to SI units that are provided for information only
Electron Devices and Lamps
and are not considered standard.
F269Test Method for Sag of Tungsten Wire
1.3 Types 1Aand 1B are designated as UNS R07005. Type
2.2 Military Standards:
2A is designated as UNS R07911. Type 2B is designated as
MIL-STD-105Sampling Procedures and Tables for Inspec-
UNS R07912.
tion by Attributes
1.4 The following precautionary caveat pertains only to the
MIL-STD-129Marking for Shipment and Storage
Chemical Analysis, Section 12 of this specification: This
standard does not purport to address all of the safety concerns,
3. Terminology
if any, associated with its use. It is the responsibility of the user
3.1 Definition of Terms Specific to This Standard:
of this standard to establish appropriate safety, health, and
3.1.1 wire—The term wire as used in this specification
environmental practices and determine the applicability of
applies to all drawn material that is spooled or coiled, and to
regulatory limitations prior to use.
short cut lengths 0.020 in. (0.51 mm) or less in diameter.
NOTE 1—A dimensional measurement method for testing nonsag
3.1.2 nonsag or doped tungsten wire—This term designates
tungsten wire above 0.030 in. (0.76 mm) in diameter is provided in Test
a wire which, when recrystallized, shows elongated interlock-
Method F269.
NOTE 2—Acceptance of nonsag wire characteristics for particular ing grains.
applicationsofsizeshallbebyagreementbetweenproducerandconsumer
3.1.3 rod—Thetermrodasusedinthisspecificationapplies
based on either a flashed microstructure as shown by photomicrographs,
to centerless ground material 0.020 in. (0.51 mm) or larger in
orondimensionalmeasurementlimitsdeterminedinaccordancewithTest
Method F269. diameter, in short cut lengths or random cut lengths.
1 2
This specification is under the jurisdiction of ASTM Committee F01 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Electronics and is the direct responsibility of Subcommittee F01.03 on Metallic contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Materials, Wire Bonding, and Flip Chip. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved April 1, 2019. Published April 2019. Originally the ASTM website.
approved in 1954. Last previous edition approved in 2014 as F288 – 96 (2014). AvailablefromStandardizationDocumentsOrderDesk,Bldg.4SectionD,700
DOI: 10.1520/F0288-96R19. Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F288−96 (2019)
4. Ordering Information 7.2 Out-of-roundness of wire or rod over 0.020 in. (0.51
mm)indiametershallbewithin5%ofthemaximumdiameter,
4.1 Orders for wire and rod furnished to this specification
when measured by a method agreed upon by supplier and
shall include the following information:
purchaser. A referee method for this test is contained in
4.1.1 Length in metres, or quantity of short cut lengths,
Procedure B of Test Methods F16.
4.1.2 Type and UNS No. (Section 1),
4.1.3 Straightness (Section 10), 7.3 Weight/Diameter Conversion Formulas:
4.1.4 Finish (Section 8), 7.3.1 TheweightofType1AwireandType1Brod(density
4.1.5 Weight or size (Section 7) and tolerance, and 19.17), is as follows:
4.1.6 Specification number.
wt inmg/200mm 5 ~diameterinmils! 31.943, or
~diameterinmm! 33011
NOTE 3—Atypical ordering description for straight chemically cleaned
wire is as follows: xxxx metres, tungsten wire, Type 1A UNS R07005,
7.3.2 The weight of Type 2A wire (density 18.80), is as
straightened, Finish 2; 280.8 mg/200 mm (63%), toASTM F288–XX.
follows:
5. Chemical Composition
wtinmg/200mm 5 diameterinmils 31.905, or
~ !
diameterinmm 32953
5.1 Thewireandrodshallconformtothechemicalrequire- ~ !
ments specified in Table 1. The sample for analysis shall be
7.3.3 The weight of Type 2B wire (density 18.50), is as
representative of the lot submitted. Lot size, sample size, and
follows:
sampling method shall be as agreed upon by the supplier and
wtinmg/200mm 5 ~diameterinmils! 31.875, or
purchaser.
diameterinmm 32906
~ !
6. Physical Properties
8. Workmanship, Finish, and Appearance
6.1 Tensile Strength—The tensile strength of a 10-in. (250-
8.1 Furnish the wire in the following finishes:
mm) gage length of wire in grams per milligram per 200 mm
8.1.1 Finish 1—Black, as-drawn,
shall be within the limits specified in Table 2 when tested in
8.1.2 Finish 2—Chemically cleaned,
accordance with 13.1.
8.1.3 Finish 3—Chemically cleaned and stress-relieved.
6.2 General Ductility Requirements —The ductility of
8.1.4 Finish 4—Reducing atmosphere cleaned and
Types 1A, 2A, and 2B wire shall be sufficient to meet the
annealed,
following requirements:
8.1.5 Finish 5—Etched, and
6.2.1 Wire up to 75 mg/200 mm, Inclusive —Six1-mlengths
8.1.6 Finish 6—Electropolished.
shall be tested in accordance with 13.2. The wire shall not
8.2 The rod shall be furnished in the following finish:
break more than two times in the six tests. Where required, a
8.2.1 Finish 7—Centerless ground.
lower limit may be negotiated between purchaser and seller.
6.2.2 Wire over 75 mg/200 mm—Thirty successive close-
9. General Requirements
wound turns completely around mandrels shall be free of
9.1 The material shall be smooth, free of twists, bends,
splittingorcrackingwhentestedinaccordancewith13.2.2and
kinks,curls,andasfreeofdents,swagingmarks,scratches,die
examined at a magnification of 30×.
marks, laps, seams, splits, slivers, inclusions, bumps, pits,
6.2.3 Special Ductility Requirements —Wire for certain
grooves, cracks, and other physical defects when examined at
applications may require a special ductility as agreed upon
amagnificationof30×asbestcommercialpracticewillpermit.
between the purchaser and the seller.
9.2 Unless black finish is specified, all types of wire shall
6.3 Surface Defects— Type 1B rod shall not show faults
have a clean finish, free of graphite, grease, oil, and lubricants.
when tested in accordance with 13.5.
All finishes shall be as free of dirt, oxide, stains, scale, and
other surface defects, as best commercial practice permits.
7. Dimensions, Weights, and Permissible Variations
Wire for hooks, supports, springs, anchors, and mesh shall
7.1 Dimensional tolerances for Type 1A (nonsag) wire for
have a bright smooth surface free of cracks, holes, or craters
use as incandescent filaments shall conform to the require-
when examined at a magnification of 10×.
ments specified in Table 3.
9.3 Rod of Type 1B shall have a bright smooth surface and
NOTE 4—Tolerances are industry standards; closer tolerances may be
be capable of making acceptable metal-to-glass seals when
obtained in certain instances, usually at a premium.
tested in accordance with Test Method F204.
A
TABLE 1 Chemical Requirements 10. Straightness
Type, Thoria, weight Tungsten, weight
10.1 When ordered as straightened, straightness of wire
UNS number % %
3.00 mg/200 mm and larger shall be specified as the radius of
1A and 1B (R07005) . 99.95 min
2A (R07911) 0.8 min, 1.2 max balance
curvature or camber of a given length of wire as agreed upon
2B (R07912) 1.7 min, 2.2 max balance
between the purchaser and supplier. For wire under 3.00
A
For all Types:
mg/200 mm, alternative methods for straightness requirements
Other elements (each)—100 ppm max.
may be used as agreed upon between the purchaser and the
Total other elements—500 ppm max.
supplier.
F288−96 (2019)
A
TABLE 2 Tensile Properties of Nonsag Tungsten Wire (Type 1A)
Tensile Strength, g/mg/200 mm
High Tensile
Medium Low Tensile
Diameter of Wire, in. Wire
Weight of Wire, mg/200 mm Tensile Wire Wire
(mm, Approximat
...