ASTM F837M-02a(2015)

Standard Specification for Stainless Steel Socket Head Cap Screws [Metric]

ABSTRACT
This specification covers stainless steel metric socket head cap screws (SHCS) intended for use in applications requiring general corrosion resistance. Two groups of stainless steel alloys are covered, austenitic Grade A1 and martensitic Grade C1. Four property classes are covered: austenitic A1-50 in an annealed condition; austenitic A1-55 in a cold worked condition; austenitic A1-70 in a cold worked condition, and martensitic C1-110 in a heat treated condition. Materials shall be tested and the individual grades shall conform to forging; threads; heat treatment; chemical composition; mechanical properties such as thread diameter, tensile strength, yield strength, elongation, core hardness (Vickers and Rockwell); and corrosion resistance values. Workmanship, finish, and appearance are also detailed.
SCOPE
1.1 This specification covers the chemical and mechanical requirements for stainless steel metric socket head cap screws (SHCS) with nominal thread M1.6 through M36 and intended for use in applications requiring general corrosion resistance.  
1.2 Two groups of stainless steel alloys are covered, austenitic Grade A1 and martensitic Grade C1.  
1.3 Four property classes are covered: austenitic A1-50 in an annealed condition at 585 MPa maximum; austenitic A1–55 in a cold worked condition at 550 MPa minimum; austenitic A1-70 in a cold worked condition at 700 MPa minimum, and martensitic C1-110 in a heat treated condition at 1100 MPa minimum.  
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.5 This hazard statement pertains only to Section 13, Test Methods:  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 and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 31-Aug-2015
• ICS: 21.060.10 - Bolts, screws, studs
• Technical Committee: F16 - Fasteners
• Drafting Committee: F16.04 - Nonferrous Fasteners

Relations

• Replaces: ASTM F837M-02a(2010) - Standard Specification for Stainless Steel Socket Head Cap Screws [Metric]
• Effective Date: 01-Sep-2015
• Replaced By: ASTM F837M-16 - Standard Specification for Stainless Steel Socket Head Cap Screws [Metric]
• Effective Date: 01-May-2016

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:F837M −02a(Reapproved 2015)
Standard Specification for
Stainless Steel Socket Head Cap Screws [Metric]
This standard is issued under the fixed designation F837M; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope A967Specification for Chemical Passivation Treatments for
Stainless Steel Parts
1.1 This specification covers the chemical and mechanical
D3951Practice for Commercial Packaging
requirements for stainless steel metric socket head cap screws
E18Test Methods for Rockwell Hardness of Metallic Ma-
(SHCS) with nominal thread M1.6 through M36 and intended
terials
for use in applications requiring general corrosion resistance.
E92TestMethodforVickersHardnessofMetallicMaterials
1.2 Two groups of stainless steel alloys are covered, auste- 3
(Withdrawn 2010)
nitic Grade A1 and martensitic Grade C1.
E384Test Method for Knoop and Vickers Hardness of
1.3 Four property classes are covered: austenitic A1-50 in Materials
F606MTest Methods for Determining the Mechanical Prop-
anannealedconditionat585MPamaximum;austeniticA1–55
in a cold worked condition at 550 MPa minimum; austenitic erties of Externally and Internally Threaded Fasteners,
Washers, and Rivets (Metric)
A1-70 in a cold worked condition at 700 MPa minimum, and
martensitic C1-110 in a heat treated condition at 1100 MPa F738M Specification for Stainless Steel Metric Bolts,
Screws, and Studs (Withdrawn 2014)
minimum.
F1470Practice for Fastener Sampling for Specified Me-
1.4 The values stated in SI units are to be regarded as
chanical Properties and Performance Inspection
standard. No other units of measurement are included in this
2.2 ASME Standard:
standard.
ASMEB18.3.1MSocketHeadCapScrews(MetricSeries)
1.5 This hazard statement pertains only to Section 13, Test
Methods: This standard does not purport to address all of the 3. Classification
safety concerns, if any, associated with its use. It is the
3.1 The designation of the property class for the two
responsibility of the user of this standard to establish appro-
materialsandconditionsofthisspecificationshallbeconsistent
priate safety and health practices and determine the applica-
with the stainless steel designations in Specification F738M.
bility of regulatory limitations prior to use.
3.2 Theausteniticstainlesssteelsocketheadcapscrewshall
2. Referenced Documents bedesignatedF837MA1-50,F837MA1-55,orF837MA1-70.
2.1 ASTM Standards: 3.3 The martensitic stainless steel socket head cap screw
shall be designated F837M C1-110.
A262Practices for Detecting Susceptibility to Intergranular
Attack in Austenitic Stainless Steels
4. Ordering Information
A342/A342MTest Methods for Permeability of Weakly
Magnetic Materials 4.1 Orders for socket head cap screws under this specifica-
tion shall include:
A380Practice for Cleaning, Descaling, and Passivation of
Stainless Steel Parts, Equipment, and Systems 4.1.1 Quantity (number of pieces of each item),
4.1.2 Name of the item (socket head cap screws, SHCS),
A751Test Methods, Practices, and Terminology for Chemi-
cal Analysis of Steel Products 4.1.3 Size (nominal diameter, thread pitch, thread class,
screw length) or part number,
4.1.4 Property class (A1-50, A1–55, A1-70, or C1-110),
This specification is under the jurisdiction of ASTM Committee F16 on
4.1.5 ASTM specification and date of issue. When date of
Fasteners and is the direct responsibility of Subcommittee F16.04 on Nonferrous
issue is not specified, fasteners shall be furnished to the latest
Fasteners.
Current edition approved Sept. 1, 2015. Published November 2015. Originally
issue,
published as F837M – 83. Last previous edition approved in 2010 as
F837M–02a(2010). DOI: 10.1520/F0837M-02AR15.
2 3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or The last approved version of this historical standard is referenced on
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM www.astm.org.
Standards volume information, refer to the standard’s Document Summary page on Available from Global Engineering Documents, 15 Inverness Way, East
the ASTM website. Englewood, CO 80112-5704, http://www.global.ihs.com.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F837M−02a (2015)
4.1.6 Supplementary requirements, if any (see S1 through 6.3 MartensiticalloyClassC1110screwsshallbehardened
S3), and tempered by heating to 1010 6 30°C sufficient for
4.1.7 Additionalspecialrequirements,ifany,tobespecified austenitization, holding for at least ⁄2 h, rapid air or oil
on the purchase order: quenching, reheating to 275°C minimum and holding for at
4.1.7.1 Forming (see 5.1), least1handthenaircoolingtoprovidethepropertiesspecified
4.1.7.2 Threading (see 5.2), in Table 1.
4.1.7.3 Surface finish (see 11.1),
7. Chemical Composition
4.1.7.4 Alloy selection (see 7.2),
4.1.7.5 Test report (see 11.2), 7.1 It is the intent of this specification that screws shall be
ordered by property class. The chemical composition of the
4.1.7.6 Additional testing (see section 12.3),
4.1.7.7 Inspection (see 13.1), screw material shall conform to the requirements of Table 2.
4.1.7.8 Rejection (see 14.1), and
7.2 Unless otherwise specified in the inquiry and purchase
4.1.7.9 Certification (see 15.1).
order (see Supplementary Requirement S2) when A1-50,
4.1.7.10 Special packaging requirements (see section
A1-55, orA1-70 property class is specified, the choice of alloy
18.1.2).
used by the manufacturer shall be clearly identified on all
certification required in the purchase order The chemical
5. Material and Manufacture
composition shall conform to the limits specified in Table 2.
5.1 Forging—Unless otherwise specified, screws in sizes
7.3 When chemical analysis is performed by the purchaser
M3 through M20 with lengths up to 10 times the nominal
using finished fasteners representing each lot, the chemical
product diameter or 150 mm, whichever is shorter, shall be
contents obtained shall conform to the limits specified inTable
cold headed except that they may be hot headed or machined
2 for the specific alloy. Chemical contents shall conform to the
byagreementwiththepurchaser.Largersizesandlengthsmay
tolerances specified in Specification A751.
be cold or hot headed. Screws smaller and larger than the M3
7.3.1 In the event of discrepancy, a referee analysis as
through M36 range may be machined. Sockets may be forged
specified in 13.1 of samples for each lot shall be made in
or machined at the option of the manufacturer.
accordance with 12.3.1.1.
5.2 Threads—Unlessotherwisespecified,screwsinsizesup
8. Mechanical Properties
to M24 inclusive and product lengths up to 150 mm inclusive
shall have threads formed by rolling, except by special agree-
8.1 Screws shall be tested in accordance with the mechani-
mentwiththepurchaser.Largerproductsmayberolled,cut,or
cal testing requirements for the property class, nominal thread
ground at the option of the manufacturer.
diameter, length, and specified minimum tensile strength as
specified in Table 3 and shall meet the mechanical require-
6. Heat Treatment
ments specified for that product in Table 1.
6.1 Austenitic alloys class A1-50 screws, following
8.2 For products on which both hardness and tension tests
manufacture, shall be annealed by heating to 1040 6 30°C to
are performed, acceptance based on tensile requirements shall
obtain maximum corrosion resistance and minimum perme-
take precedence over low hardness readings (see Table 4).
ability. The screws shall be held for a sufficient time at
temperature and then cooled at a rate sufficient to prevent 9. Corrosion Resistance
precipitation of the carbide and to provide the properties
9.1 Carbide Precipitation:
specified in Table 1.
9.1.1 Rod, bar, and wire in the austenitic alloy group A1
6.2 When Condition A1-55 or A1-70 is specified, the (not including the free-machining grade 303) used to make
austenitic alloys shall be annealed as specified in 6.1 generally fasteners in accordance with this specification shall be capable
bytherawmaterialmanufacturer,thencoldworkedtodevelop of passing the test for susceptibility to intergranular corrosion
specific properties. as specified in Practice E of Practices A262.
TABLE 1 Mechanical Property Requirements
B
Full Size Product Tests Machined Specimen Tests Core Hardness
Nominal
Tensile Yield Elon-
Property Class Thread
Tensile Strength, Minimum
A Strength, Strength, gation, Vickers Rockwell
C
Diameter
MPa Extension
MPa MPa %
A1–50 M1.6 to M36 585 max 0.6D 585 max 380 max 40 210 max 95 HRB max
A1-55 M1.6 to M20 550 min 0.4D 550 min 270 min 25 160 min 50 HRA min
A1–70 M1.6 to M20 700 min 0.4D 600 min 450 min 20 220 min 59 HRA min
C1-110 M1.6 to M5 1100 . . . . . . . . . . . . 350–440 36–45 HRC
M6 to M36 1100 0.2 D 1100 820 12 350–440 36–45 HRC
A
For A1–55 and A1–70 property class fasteners with nominal thread diameter larger than M20, the mechanical properties shall be agreed upon between the user and
manufacturer.
B
Core hardness is only required when full-size product tensile testing cannot be accomplished.
C
D denotes nominal thread size.
F837M−02a (2015)
TABLE 2 Chemical Requirements
UNS
Composition, % maximum except as shown
Property
Designation Alloy
Class
Carbon Manganese Phosphorus Sulfur Silicon Chromium Nickel Copper Molybdenum
Austenitic Alloys
A B
A1 S30300 303 0.15 2.00 0.20 0.15 min 1.00 17.0 to 19.0 8.0 to 10.0 . . . 0.60 max
A1 S30400 304 0.08 2.00 0.045 0.030 1.00 18.0 to 20.0 8.0 to 10.5 1.00 . . .
A1 S30403 304L 0.030 2.00 0.045 0.030 1.00 18.0 to 20.0 8.0 to 12.0 1.00 . . .
A1 S30500 305 0.12 2.00 0.045 0.030 1.00 17.0 to 19.0 10.5 to 13.0 1.00 . . .
A1 S38400 384 0.08 2.00 0.045 0.030 1.00 15.0 to 17.0 17.0 to 19.0 . . . . . .
A B
A1 S20300 XM1 0.08 5.0 to 6.5 0.040 0.18 to 0.35 1.00 16.0 to 18.0 5.0 to 6.5 1.75 to 2.25 0.50 max
A1 S30430 18–9LW 0.10 2.00 0.045 0.030 1.00 17.0 to 19.0 8.0 to 10.0 3.00 to 4.00 . . .
A1 S30433 302HQ 0.03 2.00 0.045 0.030 1.00 17.0 to 19.0 8.0 to 10.0 3.0 to 4.0 . . .
A1 S31600 316 0.08 2.00 0.045 0.030 1.00 16.0 to 18.0 10.0 to 14.0 . . . 2.0 to 3.0
A1 S31603 316L 0.03 2.00 0.045 0.030 1.00 16.0 to 18.0 10.0 to 14.0 . . . 2.0 to 3.0
Martensitic Alloys
C1 S4100 410 0.15 1.00 0.040 0.030 1.00 11.5 to 13.5 . . . . . . . . .
A
Free machining grades are not recommended for forged product. These grades may be furnished only when approved by the purchaser.
B
At manufacturer’s option, determined only when intentionally added.
TABLE 3 Mechanical Testing Requirements
Test conducted Using Full Size
Hardness Test Conducted Using Machined Test Specification
Product
Item Product Length
Exten- Axial Tensile Yield Strength Tensile Elonga-
max min
sion Strength 0.2 % offset Strength tion
AB B
1 #3 D . . . . .
B BB
23 D to 300 mm . . . .
B
3 Over 300 mm . A A B B B
A
D denotes nominal diameter of product.
B
Denotes mandatory test. In addition, either all tests denoted by A or all tests denoted by B shall be performed. In case of arbitration, full-size tests, denoted A, shall be
decisive.
9.1.2 AsstatedinPracticesA262,samplesmaybesubjected the socket shall not have a length exceeding 0.25 T,ora
to the faster and more severe screening test in accordance with maximum depth of 0.03 D not to exceed 0.13 mm (see Fig. 2).
Practice A. Failing Practice A, specimens shall be tested to 11.2.3 Seams in the shank shall not exceed a depth of 0.03
Practice E and be considered satisfactory if passing Practice E. D or 0.2 mm, whichever is greater.
11.2.4 No transverse discontinuities shall be permitted in
10. Dimensions
the head-to-shank fillet area.
10.1 Unless otherwise specified, the products shall conform 11.2.5 Threadsshallhavenolapsattherootorontheflanks,
as shown in Fig. 3. Laps are permitted at the crests (Fig. 3c)
totherequirementsofASMEB18.3.1MHexagonSocketHead
Cap Screws (Metric Series). that do not exceed 25% of the basic thread depth, and on the
flanks outside the pitch cylinder. Longitudinal seams rolled
11. Workmanship, Finish, and Appearance
beneath the root of the thread and across the crests of cut
threads are acceptable within the limits of 11.2.3.
11.1 Surface Treatment—Unlessotherwisespecified,screws
shall be cleaned, descaled and passivated in accordance with
12. Number of Tests
Practice A380 or Specification A967 at the option of the
12.1 The requirements of this specification shall be met in
manufacturer.
continuous mass production for stock and the manufacturer
11.2 The surface discontinuities for these products shall
shall make sample inspections to ensure that the product
conform to Specification F1470 and the additional limitations
conforms to the specified requirements. Additional tests of
specified herein.
individual shipments of fasteners are not ordinarily necessary.
11.2.1 Forgingdefectsthatconnectthesockettotheperiph-
A record of the individual heat of steel in each lot shall be
ery of the head are not permissible. Defects originating on the
maintained. The containers shall be coded to permit identifi-
periphery and with a traverse indicating a potential to intersect
cation of the lot.
are not permissible. Other forging defects are permissible
12.2 Whenspecifiedinthepurchaseorder,themanufacturer
provided those located in the bearing area, fillet, and top
shall furnish a test report of the last complete set of chemical
surfaces shall not have a depth exceeding 0.03 D or 0.13 m,
analysis and mechanical tests for each stock size in each
whichever is greater. For peripheral discontinuities, the maxi-
shipment.
mum depth may be 0.06 D (see Fig. 1).
11.2.2 Forging defects located in the socket wall within 0.1 12.3 When tests of individual shipments are required,
times the actual key engagement, T, from the bottom of the Supplementary Requirement S1 must be specified in the
socketarenotpermissible.Discontinuitieslocatedelsewherein inquiry and order.
F837M−02a (2015)
TABLE 4 Tensile Strength Values for Full Size Fasteners, kN
12.4.1 Unless otherwise specified, inspection for corrosion
resistance shall be in accordance with the manufacturer’s
Property Classes
standard quality control practices. No specific method of
A1-50 A1-55 A1-70 C1-110
Nominal Size Stress
inspection is required but the screws shall be produced from
and Thread Area, Tensile
Tensile Tensile Tensile
2 A
Strength,
Pitch mm suitable raw material and manufactured by properly controlled
Strength, Strength, Strength,
E
B C D kN
kN kN kN
practices to mai
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: F837M − 02a (Reapproved 2010) F837M − 02a (Reapproved 2015)
Standard Specification for
Stainless Steel Socket Head Cap Screws [Metric]
This standard is issued under the fixed designation F837M; 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
1.1 This specification covers the chemical and mechanical requirements for stainless steel metric socket head cap screws
(SHCS) with nominal thread M1.6 through M36 and intended for use in applications requiring general corrosion resistance.
1.2 Two groups of stainless steel alloys are covered, austenitic Grade A1 and martensitic Grade C1.
1.3 Four property classes are covered: austenitic A1-50 in an annealed condition at 585 MPa maximum; austenitic A1–55 in a
cold worked condition at 550 MPa minimum; austenitic A1-70 in a cold worked condition at 700 MPa minimum, and martensitic
C1-110 in a heat treated condition at 1100 MPa minimum.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 This hazard statement pertains only to Section 13, Test Methods: 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 and health
practices and determine the applicability of regulatory limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
A262 Practices for Detecting Susceptibility to Intergranular Attack in Austenitic Stainless Steels
A342/A342M Test Methods for Permeability of Weakly Magnetic Materials
A380 Practice for Cleaning, Descaling, and Passivation of Stainless Steel Parts, Equipment, and Systems
A751 Test Methods, Practices, and Terminology for Chemical Analysis of Steel Products
A967 Specification for Chemical Passivation Treatments for Stainless Steel Parts
D3951 Practice for Commercial Packaging
E18 Test Methods for Rockwell Hardness of Metallic Materials
E92 Test Method for Vickers Hardness of Metallic Materials (Withdrawn 2010)
E384 Test Method for Knoop and Vickers Hardness of Materials
F606M Test Methods for Determining the Mechanical Properties of Externally and Internally Threaded Fasteners, Washers, and
Rivets (Metric)
F738M Specification for Stainless Steel Metric Bolts, Screws, and Studs (Withdrawn 2014)
F1470 Practice for Fastener Sampling for Specified Mechanical Properties and Performance Inspection
2.2 ASME Standard:
ASME B 18.3.1M Socket Head Cap Screws (Metric Series)
3. Classification
3.1 The designation of the property class for the two materials and conditions of this specification shall be consistent with the
stainless steel designations in Specification F738M.
3.2 The austenitic stainless steel socket head cap screw shall be designated F837M A1-50, F837M A1-55, or F837M A1-70.
3.3 The martensitic stainless steel socket head cap screw shall be designated F837M C1-110.
This specification is under the jurisdiction of ASTM Committee F16 on Fasteners and is the direct responsibility of Subcommittee F16.04 on Nonferrous Fasteners.
Current edition approved Oct. 1, 2010Sept. 1, 2015. Published October 2010November 2015. Originally published as F837M – 83. Last previous edition approved in 2010
as F837M – 02a.F837M – 02a(2010). DOI: 10.1520/F0837M-02AR10.10.1520/F0837M-02AR15.
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 ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
Available from Global Engineering Documents, 15 Inverness Way, East Englewood, CO 80112-5704, http://www.global.ihs.com.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F837M − 02a (2015)
4. Ordering Information
4.1 Orders for socket head cap screws under this specification shall include:
4.1.1 Quantity (number of pieces of each item),
4.1.2 Name of the item (socket head cap screws, SHCS),
4.1.3 Size (nominal diameter, thread pitch, thread class, screw length) or part number,
4.1.4 Property class (A1-50, A1–55, A1-70, or C1-110),
4.1.5 ASTM specification and date of issue. When date of issue is not specified, fasteners shall be furnished to the latest issue,
4.1.6 Supplementary requirements, if any (see S1 through S3),
4.1.7 Additional special requirements, if any, to be specified on the purchase order:
4.1.7.1 Forming (see 5.1),
4.1.7.2 Threading (see 5.2),
4.1.7.3 Surface finish (see 11.1),
4.1.7.4 Alloy selection (see 7.2),
4.1.7.5 Test report (see 11.2),
4.1.7.6 Additional testing (see section 12.3),
4.1.7.7 Inspection (see 13.1),
4.1.7.8 Rejection (see 14.1), and
4.1.7.9 Certification (see 15.1).
4.1.7.10 Special packaging requirements (see section 18.1.2).
5. Material and Manufacture
5.1 Forging—Unless otherwise specified, screws in sizes M3 through M20 with lengths up to 10 times the nominal product
diameter or 150 mm, whichever is shorter, shall be cold headed except that they may be hot headed or machined by agreement
with the purchaser. Larger sizes and lengths may be cold or hot headed. Screws smaller and larger than the M3 through M36 range
may be machined. Sockets may be forged or machined at the option of the manufacturer.
5.2 Threads—Unless otherwise specified, screws in sizes up to M24 inclusive and product lengths up to 150 mm inclusive shall
have threads formed by rolling, except by special agreement with the purchaser. Larger products may be rolled, cut, or ground at
the option of the manufacturer.
6. Heat Treatment
6.1 Austenitic alloys class A1-50 screws, following manufacture, shall be annealed by heating to 1040 6 30°C to obtain
maximum corrosion resistance and minimum permeability. The screws shall be held for a sufficient time at temperature and then
cooled at a rate sufficient to prevent precipitation of the carbide and to provide the properties specified in Table 1.
6.2 When Condition A1-55 or A1-70 is specified, the austenitic alloys shall be annealed as specified in 6.1 generally by the raw
material manufacturer, then cold worked to develop specific properties.
6.3 Martensitic alloy Class C1 110 screws shall be hardened and tempered by heating to 1010 6 30°C sufficient for
austenitization, holding for at least ⁄2 h, rapid air or oil quenching, reheating to 275°C minimum and holding for at least 1 h and
then air cooling to provide the properties specified in Table 1.
7. Chemical Composition
7.1 It is the intent of this specification that screws shall be ordered by property class. The chemical composition of the screw
material shall conform to the requirements of Table 2.
TABLE 1 Mechanical Property Requirements
B
Full Size Product Tests Machined Specimen Tests Core Hardness
Nominal
Tensile Yield Elon-
Property Class Thread
Tensile Strength, Minimum
A Strength, Strength, gation, Vickers Rockwell
C
Diameter
MPa Extension
MPa MPa %
A1–50 M1.6 to M36 585 max 0.6D 585 max 380 max 40 210 max 95 HRB max
A1-55 M1.6 to M20 550 min 0.4D 550 min 270 min 25 160 min 50 HRA min
A1–70 M1.6 to M20 700 min 0.4D 600 min 450 min 20 220 min 59 HRA min
C1-110 M1.6 to M5 1100 . . . . . . . . . . . . 350–440 36–45 HRC
M6 to M36 1100 0.2 D 1100 820 12 350–440 36–45 HRC
A
For A1–55 and A1–70 property class fasteners with nominal thread diameter larger than M20, the mechanical properties shall be agreed upon between the user and
manufacturer.
B
Core hardness is only required when full-size product tensile testing cannot be accomplished.
C
D denotes nominal thread size.
F837M − 02a (2015)
TABLE 2 Chemical Requirements
UNS
Composition, % maximum except as shown
Property
Designation Alloy
Class
Carbon Manganese Phosphorus Sulfur Silicon Chromium Nickel Copper Molybdenum
Austenitic Alloys
A B
A1 S30300 303 0.15 2.00 0.20 0.15 min 1.00 17.0 to 19.0 8.0 to 10.0 . . . 0.60 max
A1 S30400 304 0.08 2.00 0.045 0.030 1.00 18.0 to 20.0 8.0 to 10.5 1.00 . . .
A1 S30403 304L 0.030 2.00 0.045 0.030 1.00 18.0 to 20.0 8.0 to 12.0 1.00 . . .
A1 S30500 305 0.12 2.00 0.045 0.030 1.00 17.0 to 19.0 10.5 to 13.0 1.00 . . .
A1 S38400 384 0.08 2.00 0.045 0.030 1.00 15.0 to 17.0 17.0 to 19.0 . . . . . .
A B
A1 S20300 XM1 0.08 5.0 to 6.5 0.040 0.18 to 0.35 1.00 16.0 to 18.0 5.0 to 6.5 1.75 to 2.25 0.50 max
A1 S30430 18–9LW 0.10 2.00 0.045 0.030 1.00 17.0 to 19.0 8.0 to 10.0 3.00 to 4.00 . . .
A1 S30433 302HQ 0.03 2.00 0.045 0.030 1.00 17.0 to 19.0 8.0 to 10.0 3.0 to 4.0 . . .
A1 S31600 316 0.08 2.00 0.045 0.030 1.00 16.0 to 18.0 10.0 to 14.0 . . . 2.0 to 3.0
A1 S31603 316L 0.03 2.00 0.045 0.030 1.00 16.0 to 18.0 10.0 to 14.0 . . . 2.0 to 3.0
Martensitic Alloys
C1 S4100 410 0.15 1.00 0.040 0.030 1.00 11.5 to 13.5 . . . . . . . . .
A
Free machining grades are not recommended for forged product. These grades may be furnished only when approved by the purchaser.
B
At manufacturer’s option, determined only when intentionally added.
7.2 Unless otherwise specified in the inquiry and purchase order (see Supplementary Requirement S2) when A1-50, A1-55, or
A1-70 property class is specified, the choice of alloy used by the manufacturer shall be clearly identified on all certification
required in the purchase order The chemical composition shall conform to the limits specified in Table 2.
7.3 When chemical analysis is performed by the purchaser using finished fasteners representing each lot, the chemical contents
obtained shall conform to the limits specified in Table 2 for the specific alloy. Chemical contents shall conform to the tolerances
specified in Specification A751.
7.3.1 In the event of discrepancy, a referee analysis as specified in 13.1 of samples for each lot shall be made in accordance with
12.3.1.1.
8. Mechanical Properties
8.1 Screws shall be tested in accordance with the mechanical testing requirements for the property class, nominal thread
diameter, length, and specified minimum tensile strength as specified in Table 3 and shall meet the mechanical requirements
specified for that product in Table 1.
8.2 For products on which both hardness and tension tests are performed, acceptance based on tensile requirements shall take
precedence over low hardness readings (see Table 4).
9. Corrosion Resistance
9.1 Carbide Precipitation:
9.1.1 Rod, bar, and wire in the austenitic alloy group A1 (not including the free-machining grade 303) used to make fasteners
in accordance with this specification shall be capable of passing the test for susceptibility to intergranular corrosion as specified
in Practice E of Practices A262.
9.1.2 As stated in Practices A262, samples may be subjected to the faster and more severe screening test in accordance with
Practice A. Failing Practice A, specimens shall be tested to Practice E and be considered satisfactory if passing Practice E.
10. Dimensions
10.1 Unless otherwise specified, the products shall conform to the requirements of ASME B18.3.1M Hexagon Socket Head Cap
Screws (Metric Series).
TABLE 3 Mechanical Testing Requirements
Test conducted Using Full Size
Hardness Test Conducted Using Machined Test Specification
Product
Item Product Length
Exten- Axial Tensile Yield Strength Tensile Elonga-
max min
sion Strength 0.2 % offset Strength tion
A B B
1 #3 D . . . . . . . . . . . . . . .
B B B
2 3 D to 300 mm . . . . . . . . . . . .
B
3 Over 300 mm . . . A A B B B
A
D denotes nominal diameter of product.
B
Denotes mandatory test. In addition, either all tests denoted by A or all tests denoted by B shall be performed. In case of arbitration, full-size tests, denoted A, shall be
decisive.
F837M − 02a (2015)
TABLE 4 Tensile Strength Values for Full Size Fasteners, kN
Property Classes
A1-50 A1-55 A1-70 C1-110
Nominal Size Stress
and Thread Area, Tensile
Tensile Tensile Tensile
2 A
Strength,
Pitch mm
Strength, Strength, Strength,
E
kN
B C D
kN kN kN
M1.6 × 0.35 1.27 0.74 0.70 0.89 1.40
M2 × 0.4 2.07 1.21 1.14 1.45 2.28
M2.5 × 0.45 3.39 1.98 1.87 2.37 3.73
M3 × 0.5 5.03 2.94 2.77 3.52 5.53
M3.5 × 0.6 6.78 3.97 3.73 4.75 7.46
M4 × 0.7 8.78 5.14 4.83 6.15 9.66
M5 × 0.8 14.2 8.30 7.80 9.93 15.6
M6 × 1 20.1 11.8 11.1 14.1 22.1
M8 × 1.25 36.6 21.4 20.1 25.6 40.3
M10 × 1.5 58.0 33.9 31.9 40.6 63.8
M12 × 1.75 84.3 49.3 46.3 59.0 92.7
M14 × 2 115 67.5 63.5 80.8 126.5
M16 × 2 157 91.7 86.2 110 173
M20 × 2.5 245 143 135 171 270
M24 × 3 353 206 . . . . . . 388
M30 × 3.5 561 328 . . . . . . 617
M36 × 4 817 478 . . . . . . 899
A 2
Stress Area = 0.7854 ( D - 0.9382P)
where:
D = nominal thread diameter, mm, and
P = thread pitch, mm.
B
Tensile based on stress area and 585 MPa maximum.
C
Tensile based on stress area and 550 MPa minimum through M20
D
Tensile based on stress area and 700 MPa minimum through M20.
E
Tensile based on stress area and 1100 MPa minimum.
11. Workmanship, Finish, and Appearance
11.1 Surface Treatment—Unless otherwise specified, screws shall be cleaned, descaled and passivated in accordance with
Practice A380 or Specification A967 at the option of the manufacturer.
11.2 The surface discontinuities for these products shall conform to Specification F1470 and the additional limitations specified
herein.
11.2.1 Forging defects that connect the socket to the periphery of the head are not permissible. Defects originating on the
periphery and with a traverse indicating a potential to intersect are not permissible. Other forging defects are permissible provided
those located in the bearing area, fillet, and top surfaces shall not have a depth exceeding 0.03 D or 0.13 m, whichever is greater.
For peripheral discontinuities, the maximum depth may be 0.06 D (see Fig. 1).
11.2.2 Forging defects located in the socket wall within 0.1 times the actual key engagement, T, from the bottom of the socket
are not permissible. Discontinuities located elsewhere in the socket shall not have a length exceeding 0.25 T, or a maximum depth
of 0.03 D not to exceed 0.13 mm (see Fig. 2).
11.2.3 Seams in the shank shall not exceed a depth of 0.03 D or 0.2 mm, whichever is greater.
11.2.4 No transverse discontinuities shall be permitted in the head-to-shan
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