ASTM B388-06(2018)

Standard Specification for Thermostat Metal Sheet and Strip

ABSTRACT
This specification covers the standard for thermostat metals in the form of sheet or strip proposed for use as temperature-sensitive elements of devices for controlling, compensating, or indicating temperature. Metals shall adhere to physical requirements such as maximum sensitivity range, maximum recommended temperature, flexibility, electrical resistivity, modulus of elasticity, specific heat, density, and hardness.
SCOPE
1.1 This specification covers thermostat metals in the form of sheet or strip that are used for the temperature-sensitive elements of devices for controlling, compensating, or indicating temperature and is intended to supply acceptance requirements to purchasers ordering this material by type designation.  
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 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 become familiar with all hazards including those identified in the appropriate Safety Data Sheet (SDS) for this product/material as provided by the manufacturer, to establish appropriate safety, health, and environmental practices, and determine the applicability of regulatory limitations prior to use.  
1.4 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-2018
• ICS: 77.150.99 - Other products of non-ferrous metals
• Technical Committee: B02 - Nonferrous Metals and Alloys
• Drafting Committee: B02.10 - Thermostat Metals and Electrical Resistance Heating Materials

Relations

• Replaces: ASTM B388-06(2012) - Standard Specification for Thermostat Metal Sheet and Strip
• Effective Date: 01-Apr-2018
• Refers: ASTM B478-23 - Standard Test Method for Cross Curvature of Thermostat Metals
• Effective Date: 01-Nov-2023
• Refers: ASTM B106-08(2019) - Standard Test Methods for Flexivity of Thermostat Metals
• Effective Date: 01-Nov-2019
• Refers: ASTM B478-85(2016) - Standard Test Method for Cross Curvature of Thermostat Metals
• Effective Date: 01-May-2016
• Refers: ASTM B106-08(2013) - Standard Test Methods for Flexivity of Thermostat Metals
• Effective Date: 01-Aug-2013
• Refers: ASTM B223-08(2013) - Standard Test Method for Modulus of Elasticity of Thermostat Metals (Cantilever Beam Method)
• Effective Date: 01-Aug-2013
• Refers: ASTM B63-07(2013) - Standard Test Method for Resistivity of Metallically Conducting Resistance and<brk/> Contact Materials
• Effective Date: 01-May-2013
• Refers: ASTM B753-07(2013) - Standard Specification for Thermostat Component Alloys
• Effective Date: 01-May-2013
• Refers: ASTM E384-10 - Standard Test Method for Microindentation Hardness of Materials
• Effective Date: 01-Feb-2010
• Refers: ASTM E384-10e1 - Standard Test Method for Knoop and Vickers Hardness of Materials
• Effective Date: 01-Feb-2010
• Refers: ASTM E384-09 - Standard Test Method for Microindentation Hardness of Materials
• Effective Date: 01-May-2009
• Refers: ASTM B478-85(2008) - Standard Test Method for Cross Curvature of Thermostat Metals
• Effective Date: 01-Nov-2008
• Refers: ASTM B389-81(2008) - Standard Test Method for Thermal Deflection Rate of Spiral and Helical Coils of Thermostat Metal
• Effective Date: 01-Nov-2008
• Refers: ASTM B106-08 - Standard Test Methods for Flexivity of Thermostat Metals
• Effective Date: 01-Apr-2008
• Refers: ASTM B362-91(2008) - Standard Test Method for Mechanical Torque Rate of Spiral Coils of Thermostat Metal
• Effective Date: 01-Apr-2008

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:B388 −06(Reapproved 2018)
Standard Specification for
Thermostat Metal Sheet and Strip
This standard is issued under the fixed designation B388; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope Coils of Thermostat Metal
B389 TestMethodforThermalDeflectionRateofSpiraland
1.1 This specification covers thermostat metals in the form
Helical Coils of Thermostat Metal
of sheet or strip that are used for the temperature-sensitive
B478 TestMethodforCrossCurvatureofThermostatMetals
elements of devices for controlling, compensating, or indicat-
B753 Specification for Thermostat Component Alloys
ing temperature and is intended to supply acceptance require-
C351 Test Method for Mean Specific Heat of Thermal
ments to purchasers ordering this material by type designation.
Insulation (Withdrawn 2008)
1.2 The values stated in inch-pound units are to be regarded
E92 Test Methods for Vickers Hardness and Knoop Hard-
as standard. The values given in parentheses are mathematical
ness of Metallic Materials
conversions to SI units that are provided for information only
E384 Test Method for Microindentation Hardness of Mate-
and are not considered standard.
rials
1.3 This standard does not purport to address all of the
3. Terminology
safety concerns, if any, associated with its use. It is the
3.1 Definitions:
responsibility of the user of this standard to become familiar
3.1.1 thermostat metal, n—a composite material comprising
with all hazards including those identified in the appropriate
two or more metallic layers of differing coefficients of thermal
Safety Data Sheet (SDS) for this product/material as provided
expansion such that the radius of curvature of the composite
by the manufacturer, to establish appropriate safety, health,
changes with temperature change.
and environmental practices, and determine the applicability
of regulatory limitations prior to use.
4. Ordering Information
1.4 This international standard was developed in accor-
4.1 Orders for material under this specification shall include
dance with internationally recognized principles on standard-
the following information:
ization established in the Decision on Principles for the
4.1.1 Type designation (Table 1 and Table 2),
Development of International Standards, Guides and Recom-
4.1.2 Thickness (see 9.1),
mendations issued by the World Trade Organization Technical
4.1.3 Width (see 9.2),
Barriers to Trade (TBT) Committee.
4.1.4 Temper (designated as percent cold reduction as
needed),
2. Referenced Documents
4.1.5 Marking to identify vendor, type, high-expansion side
2.1 ASTM Standards:
or low-expansion side,
B63 Test Method for Resistivity of Metallically Conducting
4.1.6 Weight.
Resistance and Contact Materials
B106 Test Methods for Flexivity of Thermostat Metals
5. Material Segregation
B223 Test Method for Modulus of Elasticity of Thermostat
5.1 The thermostat metal shall be supplied segregated into
Metals (Cantilever Beam Method)
two groups after slitting: (1) the burr on the low-expansive
B362 Test Method for Mechanical Torque Rate of Spiral
component, and (2) the burr on the high-expansive component.
These two groups shall be identified and packaged separately
or together as mutually agreed upon between the producer and
This specification is under the jurisdiction of ASTM Committee B02 on
the user.
Nonferrous Metals and Alloys and is the direct responsibility of Subcommittee
B02.10 on Thermostat Metals and Electrical Resistance Heating Materials.
6. Chemical Composition
Current edition approved April 1, 2018. Published April 2018. Originally
approved in 1962. Last previous edition approved in 2012 as B388 – 06 (2012).
6.1 The nominal composition of component materials is
DOI: 10.1520/B0388-06R18.
given in Table 1.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on The last approved version of this historical standard is referenced on
the ASTM website. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B388−06(2018)
TABLE 1 Composition
NOTE 1—TM6 and TM7 are no longer manufactured due to availability, difficulty to produce, commercial interest, or combinations thereof.
ASTM Type
Element TM1 TM2 TM3 TM4 TM5 TM8 TM9
Nominal chemical high-expansive nickel 22 10 25 25 25 10 22
composition, component chromium 3 . 8.5 8.5 8.5 . 3
weight,% manganese . 72 . . . 72 .
copper . 18 . . . 18 .
iron 75 . 66.5 66.5 66.5 . 75
aluminum . . . . . . .
carbon . . . . . . .
intermediate nickel . . . . . . 100
component manganese . . . . . . .
low-expansive nickel 36 36 42 45 50 36 36
component iron 64 64 58 55 50 64 64
cobalt . . . . . . .
Component ratio, high-expansive 50 53 50 50 50 80 27
thickness, % component
intermediate . . . . . . 46
component
low-expansive 50 47 50 50 50 20 27
component
ASTM Type
Element TM10 TM11 TM12 TM13 TM14 TM15 TM16
Nominal chemical high-expansive nickel 22 22 22 22 22 22 22
composition, component chromium 3 3 3 3 3 3 3
weight,% manganese . . . . . . .
copper . . . . . . .
iron 7575 7575 757575
aluminum . . . . . . .
carbon . . . . . . .
intermediate nickel 100 100 100 100 100 100 100
component manganese . . . . . . .
low-expansive nickel 36 36 36 36 36 36 36
component iron 64 64 64 64 64 64 64
cobalt . . . . . . .
Component ratio, high-expansive 34 36 40 42 44 47 48
thickness, % component
intermediate 32 28 20 16 12 6 4
component
low-expansive 34 36 40 42 44 47 48
component
ASTM Type
Element
TM17 TM18 TM19 TM20 TM21 TM22 TM23
Nominal chemical high-expansive nickel 22 19.4 19.4 18 18 100 10
composition, component chromium 3 2.25 2.25 11.5 11.5 . .
weight,% manganese . . . . . . 72
copper . . . . . . 18
iron 75 78.3 78.3 70.5 70.5 . .
aluminum . . . . . . .
carbon . 0.5 0.5 . . . .
intermediate nickel 100 . . . . . .
component manganese . . . . . . .
low-expansive nickel 36 42 39 36 42 36 42
component iron 64 58 61 64 58 64 58
cobalt . . . . . . .
Component ratio, high-expansive 49 50 50 50 50 50 54
thickness,% component
intermediate 2 . . . . . .
component
low-expansive 49 50 50 50 50 50 46
component
ASTM Type
Element TM24 TM25 TM26 TM27 TM28 TM29 TM30
Nominal chemical high-expansive nickel 22 22 22 22 22 20 22
composition, component chromium 3 3 3 3 3 . 3
weight, % manganese . . . . . 6.5 .
copper . . . . . . .
iron 75 75 75 75 75 73.5 75
aluminum . . . . . . .
carbon . . . . . . .
intermediate copper 100 100 100 100 100 . .
component manganese . . . . . . .
B388−06(2018)
TABLE1 Continued
ASTM Type
Element TM24 TM25 TM26 TM27 TM28 TM29 TM30
low-expansive nickel 36 36 36 36 36 36 42
component iron 64 64 64 64 64 64 58
cobalt . . . . . . .
ASTM Type
TM24 TM25 TM26 TM27 TM28 TM29 TM30
Component ratio, resistivity ohm cir 20 30 50 70 90 477 415
thickness, % mil/ft
high-expansive 10 20 31 38 42 50 50
component
intermediate 53 35 20 14 10 . .
component
low-expansive 37 45 49 48 48 50 50
component
ASTM Type
Element TM31 TM32 TM33 TM34 TM35 TM36
Nominal chemical high-expansive nickel 10 10 10 10 19 25
composition, component chromium . . . . 2 8
weight, % manganese 72 72 72 72 . .
copper 18 18 18 18 . .
iron . . . . 79 67
aluminum . . . . . .
carbon . . . . . .
intermediate copper 100 100 100 100 . .
component manganese . . . . . .
low-expansive nickel 36 36 36 36 36 36
component iron 64 64 64 64 64 64
cobalt . . . . . .
ASTM Type
TM31 TM32 TM33 TM34 TM35 TM36
Component ratio, resistivity ohm cir 30 150 50 70 482 500
thickness, % mil/ft
high-expansive 26 50 42 45 50 50
component
intermediate 38 6 21 15 . .
component
low-expansive 36 44 37 40 50 50
component
6.1.1 The component alloys shall be as specified in Speci- in thermostat metal combinations, yield product in confor-
fication B753.
mance with the values designated in Table 2 and Table 3.
8.3.1 Flexivity shall be determined by Test Methods B106,
7. Component Ratio
Method A.
7.1 Thetypicalthicknessratioofthecomponentmaterialsis
8.3.2 Residual stress loading can affect flexivity test results.
given in Table 1. The component thickness ratios are given for
Specimensshallbestabilizedpriortotestingbystressrelieffor
reference as they are lot-to-lot variable to produce required
1 h at 500°F (260°C). Suitable stress relief conditions must be
flexivity and resistivity. Barrier(s) layer(s) for stability of
determined for individual end use applications. Initial condi-
resistivity is (are) allowable. Flexivity may vary.
tion recommendations are given in Table 2.
8. Physical Requirements
8.4 Electrical Resistivity—The electrical resistivity shall
conformtothevaluesgiveninTable2andTable3.Component
8.1 Maximum Sensitivity Range—Thetemperaturerangesof
materials designated in Specification B753 shall, in thermostat
maximum thermal response of designated types of thermostat
metal combinations, yield product in conformance with the
metals are given in Table 2 and Table 3. These are nominal
values designated in Table 2 and Table 3.
values presented only to aid users in designing devices.
8.4.1 Electrical resistivity shall be determined by Test
8.2 Maximum Recommended Temperature—The maximum
Method B63 at 75°F (24°C).
recommended temperatures of use of designated types of
thermostat metals are given in Table 2 and Table 3. These
8.5 Modulus of Elasticity—The nominal moduli of elasticity
values are presented to aid users in designing devices.
of designated thermostat metals at a temperature of 75°F
8.3 Flexivity—The flexivity of a designated thermostat (24°C) are given in Table 2 and Table 3. These are nominal
values presented to aid users in designing devices and shall not
metal shall conform to the values in Table 2 and Table 3.
Component materials designated in Specification B753 shall, be used for rejection or acceptance purposes.
B388−06(2018)
TABLE 2 Properties of Thermostat Metals (Inch-Pound Units)
NOTE 1—TM6 and TM7 are no longer manufactured due to availability, difficulty to produce, commercial interest, or combinations thereof.
ASTM Type
Properties Units
TM1 TM2 TM3 TM4 TM5 TM8 TM9
Maximum sensitivity °F 0 to 300 0 to 400 200 to 600 250 to 700 300 to 850 0 to 400 0 to 300
temperature range
Maximum recommended °F 1000 500 1000 1000 1000 500 900
temperature
−6
Flexivity × 10 50 to 200°F 15.0 ± 5 % 21.7 ± 5 % 10.4 ± 6 % 8.6 ± 6 % 6.4 ± 6 % 15.6 ± 8 % 11.5 ± 10 %
100 to 300°F 14.6 ± 5 % 21.1 ± 5 % 10.6 ± 6 % 9.0 ± 6 % 6.6 ± 6 % 15.6 ± 8 % 11.2 ± 10 %
Heat treatment °F 700 500 700 700 700 500 700
Electrical resistivity at Ω·cmil/ft 475 ± 4 % 675 ± 5 % 435 ± 4 % 400 ± 4 % 345 ± 5 % 850 ± 5 % 100 ± 5.5 %
75°F Ω·mil /ft 373±4% 530±5% 342±4% 314±4% 271±5% 668±5% 78±5.5%
Modulus of elasticity psi × 10 25 20 25 25 25.5 19.5 26
Density lb/in. 0.29 0.28 0.29 0.29 0.29 0.27 0.31
TM10 TM11 TM12 TM13 TM14 TM15 TM16
Maximum sensitivity °F 0 to 300 0 to 300 0 to 300 0 to 300 0 to 300 0 to 300 0 to 300
temperature range
Maximum recommended °F 900 900 900 900 900 900 900
temperature
−6
Flexivity × 10 50 to 200°F 13.1 ± 6 % 13.2 ± 6 % 13.7± 5.5 % 14.0 ± 5.5 % 14.7 ± 5.5 % 14.8 ± 5.5 % 14.9 ± 5.5 %
100 to 300°F 12.7 ± 6 % 13.3 ± 6 % 13.7 ± 5.5 % 14.0 ± 5.5 % 14.3 ± 5.5 % 14.4 ± 5.5 % 14.6 ± 5.5 %
Heat treatment °F 700 700 700 700 700 700 700
Electrical resistivity at Ω·cmil/ft 125 ± 5.5 % 150 ± 5.5 % 175 ± 5.5 % 200 ± 5.5 % 250 ± 5.5 % 300 ± 5.5 % 350 ± 5.5 %
75°F Ω·mil /ft 98 ± 5.5 % 118 ± 5.5 % 137 ± 5.5 % 157 ± 5.5 % 196 ± 5.5 % 236 ± 5.5 % 275± 5.5 %
Modulus of elasticity psi × 10 26 26 25.5 25.5 25.5 25 25
Density lb/in. 0.30 0.30 0.30 0.30 0.30 0.30 0.29
TM17 TM18 TM19 TM20 TM21 TM22 TM23
Maximum sensitivity °F 0 to 300 200 to 600 150 to 450 0 to 300 200 to 600 0 to 300 200 to 600
temperature range
Maximum recommended °F 900 900 900 900 900 900 500
temperature
−6
Flexivity × 10 50 to 200°F 15.0 ± 5.5 % 11.9 ± 7 % 14.4 ± 7 % 13.8 ± 5 % 10.7 ± 7 % 10.2 ± 5 % 18.3 ± 5 %
100 to 300°F 14.6 ± 5.5 % 11.9 ± 7 % 14.1 ± 7 % 13.5 ± 5 % 10.9 ± 7 % 10.2 ± 5 % 18.6± 5 %
Heat treatment °F 700 700 700 700 700 700 500
Electrical resistivity at Ω·cmil/ft 400 ± 5.5 % 420 ± 4 % 456 ± 5 % 479 ± 4 % 418 ± 4 % 92 ± 6 % 565 ± 4 %
75°F Ω·mil /ft 314±5.5% 330±4% 358±5% 376±4% 328±4% 72±6% 444±4%
Modulus of elasticity psi × 10 25 25 25 25 25 26 20
Density lb/in. 0.29 0.29 0.29 0.29 0.29 0.31 0.28
TM24 TM25 TM26 TM27 TM28 TM29 TM30
Maximum sensitivity °F 0 to 300 0 to 300 0 to 300 0 to 300 0 to 300 0 to 300 200 to 600
temperature range
Maximum recommended °F 500 500 500 500 500 1000 1000
temperature
−6
Flexivity × 10 50 to 200°F 13.1 ± 5 % 14.0 ± 5 % 14.7 ± 5 % 14.7 ± 5 % 14.8 ± 5 % 15.8 ± 6 % 11.8 ± 6 %
100 to 300°F 12.9 ± 5 % 13.6 ± 5 % 14.2 ± 5 % 14. 4± 5 % 14.6 ± 5 % 15.6 ± 6 % 12.2 ± 6 %
Heat treatment °F 500 500 500 500 500 700 700
Electrical resistivity at Ω·cmil/ft 20 ± 10 % 30 ± 7.5 % 50 ± 7.5 % 70 ± 7.5 % 90 ± 5 % 477 ± 4 % 415 ± 4 %
75°F Ω·mil /ft 15.7 ± 10 % 23.6 ± 7.5 % 39.3 ± 7.5 % 55± 7.5 % 70.6 ± 5 % 375 ± 4 % 326 ± 4 %
Modulus of elasticity psi × 10 24 24 23 23 22 25 25
Density lb/in. 0.29 0.29 0.29 0.29 0.29 0.29 0.29
TM31 TM32 TM33 TM34 TM35 TM36
Maximum sensitivity °F 0 to 300 0 to 300 0 to 300 0 to 300 0 to 300 0 to 300
temperature range
Maximum recommended °F 500 500 500 500 900 900
temperature
−6
Flexivity × 10 50 to 200°F 18.9 ± 5 % 21.7 ± 5 % 20.8 ± 5 % 21.4 ± 5 % 15.2 ± 7 % 13.7 ± 5 %
100 to 300°F 18.7 ± 5 % 20.8 ± 5 % 20.1 ± 5 % 20.3 ± 5 % 14.9 ± 7 % 13.3 ± 5 %
Heat treatment °F 500 500 500 500 700 700
Electrical resistivity at Ω·cmil/ft 30 ± 10 % 150 ± 5 % 50 ± 10 % 70 ± 8 % 482 ± 4 % 500 ± 4 %
75°F Ω·mil /ft 23.6 ± 10 % 117.8 ± 5 % 39.3 ± 10 % 55 378.6 ± 4 % 392.7 ± 4 %
Modulus of elasticity psi × 10 19 19 19 19 25 24
Density lb/
...