ASTM F879M-02a(2008)
(Specification)Standard Specification for Stainless Steel Socket Button and Flat Countersunk Head Cap Screws (Metric)
Standard Specification for Stainless Steel Socket Button and Flat Countersunk Head Cap Screws (Metric)
ABSTRACT
This specification covers the chemical and mechanical requirements for stainless steel metric hexagon socket button (SBHCS) and flat countersunk (SFHCS) head cap screws with nominal thread M 3 through M 20 intended for use in applications requiring general corrosion resistance. These steels are designated into three classes: Austenitic Class A 1-50 in an annealed condition, Austenitic Class A1-55 in a cold worked condition, and Austenitic Class A 1-70 in a cold worked condition. The austenitic stainless steel socket screw shall be designated F879M A1-50, F879M A1–55, or F 879M A1-70. Screws shall be formed by upsetting or extruding, or both. Also, these screws shall be roll threaded. Austenitic alloys ClassA 1-50 screws, following manufacture, shall be annealed by heating to a certain temperature to obtain maximum corrosion resistance and minimum permeability. The screws shall be held for a sufficient time at temperature, then cooled at a rate sufficient to prevent precipitation of the carbide and provide the properties specified. Different tests shall be conducted in order to determine the following mechanical properties of screws: tensile strength, minimum extension, yield strength, elongation, Vickers hardness, and Rockwell hardness.
SCOPE
1.1 This specification covers the chemical and mechanical requirements for stainless steel metric hexagon socket button (SBHCS) and flat countersunk (SFHCS) head cap screws with nominal thread M 3 through M 20 intended for use in applications requiring general corrosion resistance.
1.2 The following three property classes are covered:
1.2.1 Austenitic Class A 1-50 in an annealed condition at 585 MPa maximum,
1.2.2 Austenitic Class A1–55 in a cold worked condition at 550 MPa minimum, and
1.2.3 Austenitic Class A 1-70 in a cold-worked condition at 700 MPa minimum.
1.3 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 The following hazard caveat pertains only to Section 12, Test Methods: This standard does not purport to address all of the safety problems, 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.
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Designation:F879M −02a(Reapproved 2008)
Standard Specification for
Stainless Steel Socket Button and Flat Countersunk Head
Cap Screws (Metric)
This standard is issued under the fixed designation F879M; 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 A555/A555MSpecification for General Requirements for
Stainless Steel Wire and Wire Rods
1.1 This specification covers the chemical and mechanical
A751Test Methods, Practices, and Terminology for Chemi-
requirements for stainless steel metric hexagon socket button
cal Analysis of Steel Products
(SBHCS) and flat countersunk (SFHCS) head cap screws with
A967Specification for Chemical PassivationTreatments for
nominal thread M3 through M20 intended for use in applica-
Stainless Steel Parts
tions requiring general corrosion resistance.
D3951Practice for Commercial Packaging
1.2 The following three property classes are covered:
E18Test Methods for Rockwell Hardness of Metallic Ma-
1.2.1 Austenitic Class A1-50 in an annealed condition at
terials
585 MPa maximum,
E92TestMethodforVickersHardnessofMetallicMaterials
1.2.2 Austenitic ClassA1–55 in a cold worked condition at 3
(Withdrawn 2010)
550 MPa minimum, and
E384Test Method for Knoop and Vickers Hardness of
1.2.3 Austenitic Class A1-70 in a cold-worked condition at
Materials
700 MPa minimum.
F606MTest Methods for Determining the Mechanical Prop-
1.3 Units—The values stated in SI units are to be regarded erties of Externally and Internally Threaded Fasteners,
Washers, and Rivets (Metric)
asstandard.Nootherunitsofmeasurementareincludedinthis
standard. F738M Specification for Stainless Steel Metric Bolts,
Screws, and Studs
1.4 ThefollowinghazardcaveatpertainsonlytoSection12,
F788/F788MSpecification for Surface Discontinuities of
Test Methods:This standard does not purport to address all of
Bolts, Screws, and Studs, Inch and Metric Series
the safety problems, if any, associated with its use. It is the
F1470Practice for Fastener Sampling for Specified Me-
responsibility of the user of this standard to establish appro-
chanical Properties and Performance Inspection
priate safety and health practices and determine the applica-
2.2 ASME Standards:
bility of regulatory limitations prior to use.
B18.3.4MHexagon Socket Button Head Cap Screws (Met-
ric Series)
2. Referenced Documents
B18.3.5MHexagon Socket Flat Countersunk Head Cap
2.1 ASTM Standards: 4
Screws (Metric Series)
A262Practices for Detecting Susceptibility to Intergranular
Attack in Austenitic Stainless Steels 3. Classification
A342/A342MTest Methods for Permeability of Weakly
3.1 The designation of the property class and conditions of
Magnetic Materials
this specification shall be consistent with the stainless steel
A380Practice for Cleaning, Descaling, and Passivation of
designations in Specification F738M.
Stainless Steel Parts, Equipment, and Systems
3.2 The austenitic stainless steel socket screw shall be
designated F879M A1-50, F879M A1–55, or F879M A1-70.
This specification is under the jurisdiction of ASTM Committee F16 on
4. Ordering Information
Fasteners and is the direct responsibility of Subcommittee F16.04 on Nonferrous
4.1 Ordersformaterialunderthisspecificationshallinclude
Fasteners.
Current edition approved May 1, 2008. Published August 2008. Originally
the following information:
approved in 1984. Last previous edition approved in 2002 as F879–02a. DOI:
10.1520/F0879M-02AR08.
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 service@astm.org. 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
F879M−02a (2008)
4.1.1 Quantity (number of pieces of each item). 6.3.1 In the event of a discrepancy, a referee analysis of the
4.1.2 Name of the screw, SBHCS or SFHCS. samples for each lot as specified in 12.1, shall be made in
4.1.3 Dimensions, including nominal thread designation, accordance with 11.3.
thread pitch, and nominal screw length (millimetres). A stan-
dard part number may be used for this definition.
7. Mechanical Properties
4.1.4 Property Class A1-50, A1–55, or A1-70.
7.1 The finished screws shall conform to the mechanical
4.1.5 Certification, if required (see Section 15).
requirements specified in Table 1.
4.1.6 ASTM specification and year of issue.
7.2 Screws having a nominal length equal to or greater than
4.1.7 Any special or supplemental requirements (see
three diameters shall be tensile tested full size and shall meet
Supplementary Requirements S1 through S3).
the full size breaking strength requirements specified in Table
5. Materials and Manufacture
3. Tensile failures through the head are acceptable providing
the load requirements are satisfied.
5.1 Screws shall be formed by upsetting or extruding, or
both.
7.3 Screws that are too short (lengths less than specified in
7.2 or that have insufficient threads for tension testing) shall
5.2 Screws shall be roll threaded.
not be subject to tension tests, but shall conform to the
5.3 Heat Treatment—Austenitic alloys Class A1-50 screws,
hardness requirements of Table 1.
followingmanufacture,shallbeannealedbyheatingto1040 6
30°C to obtain maximum corrosion resistance and minimum
8. Corrosion Resistance Requirements
permeability. The screws shall be held for a sufficient time at
8.1 Carbide Precipitation:
temperature, then cooled at a rate sufficient to prevent precipi-
8.1.1 Austenitic alloy rod, bar, and wire used to make
tation of the carbide and provide the properties specified in
fasteners in accordance with this specification shall be capable
Table 1.
of passing the test for susceptibility to intergranular corrosion
5.4 When Property Class A1-55 or A1-70 is specified, the
as specified in Practice E of Practice A262.
austeniticalloysshallbeannealedasspecifiedin5.3,generally
8.1.2 AsstatedinPracticesA262,samplesmaybesubjected
bytherawmaterialmanufacturer,thencoldworkedtodevelop
to the faster and more severe screening test in accordance with
specific properties.
Practice A. Failing Practice A, specimens shall be tested to
PracticeEandbeconsideredsatisfactoryifpassingPracticeE.
6. Chemical Composition
8.1.3 If the fasteners pass the requirements of 8.1.1, they
6.1 It is the intent of this specification that screws shall be
shall be considered acceptable. If they fail, they shall be tested
ordered by property class. The chemical composition of the
in accordance with Practice C of Practices A262 and shall
screws shall conform to the requirements of Table 2.
show a corrosion rate not exceeding 0.05 mm/month.
6.2 Unless otherwise specified in the inquiry and purchase
order (see Supplementary Requirement S2), the choice of
9. Dimensions
stainlesssteelusedshallbethatofthefastenermanufactureras
9.1 Unless otherwise specified, the dimensions shall con-
determined by his fabrication methods and material availabil-
form to the requirements of ASME B18.3.4M or ASME
ity. The specific stainless steel used by the manufacturer shall
B18.3.5M, as specified.
beclearlyidentifiedonallcertificationrequiredinthepurchase
orderandshallhaveachemicalcompositionconformingtothe
10. Workmanship, Finish, and Appearance
limits specified in Table 2.
10.1 Surface Treatment—Unlessotherwisespecified,screws
6.3 When chemical analysis is performed by the purchaser
shall be cleaned, descaled and passivated in accordance with
using finished fasteners, the chemical composition obtained
Practice A380 or Specification A967 at the option of the
shall conform to the limits specified in Table 2 for the specific
manufacturer.
alloy. Chemical composition shall conform to the tolerances
specified in Specification A555/A555M. 10.2 Surface Discontinuities:
TABLE 1 Mechanical Property Requirements
Full Size
B
Machined Specimen Tests Core Hardness
Product Tests
Nominal Thread
Property Class
A
Diameter
Tensile Minimum Tensile Yield Strength, Elongation,
Vickers Rockwell
C
Strength, MPa Extension Strength, MPa MPa %, min
A1-50 M3–M20 585 max 0.6D 585 max 380 max 40 210 max 95 HRB max
A1–55 M3–M20 550 min 0.4D 550 min 270 min 25 160 min 50 HRA min
A1–70 M3–M20 700 min 0.4D 600 min 450 min 20 220 min 59 HRA min
A
Actual full-size testing of Class A1–55 and A1–70 may result in decreased tensile strength because of the head configuration (see Table 3). For fasteners with nominal
thread diameters 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.
F879M−02a (2008)
TABLE 2 Chemical Requirements
Composition, % maximum except as shown
UNS
Alloy
Designation
Carbon Manganese Phosphorus Sulfur Silicon Chromium Nickel Copper Molybdenum
S30400 304 0.08 2.00 0.045 0.030 1.00 18.0 to 20.0 8.0 to 10.5 1.00 . . .
S30403 304L 0.030 2.00 0.045 0.030 1.00 18.0 to 20.0 8.0 to 12.0 1.00 . . .
S30500 305 0.12 2.00 0.045 0.030 1.00 17.0 to 19.0 10.5 to 13.0 1.00 . . .
S38400 384 0.08 2.00 0.045 0.030 1.00 15.0 to 17.0 17.0 to 19.0 . . .
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 . . .
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 . . .
S31600 316 0.08 2.00 0.045 0.030 1.00 16.0 to 18.0 10.0 to 14.0 2.00 to 3.00
S31603 316L 0.03 2.00 0.045 0.030 1.00 16.0 to 18.0 10.0 to 14.0 2.00 to 3.0
TABLE 3 Breaking Strength Values for Full Size Fasteners
NOTE 1—Breaking loads are based on tensile stress area and strengths
of585MPamaxforA1-50,550MPaforA1–55,and700MPaminA1-70.
TheminimumloadsforpropertyclassesA1–55andA1-70arereducedby
20%toallowfortheheadcriticalnatureoftheseconfigurations.SeeNote
Ain Table 1.Actual strength of the threaded section, if size permits, may
be determined by removing the head and testing the threaded section as a
stud.
Property Class
Nominal Size and Stress Area,
A1–50 A1–55 A1–70
Thread Pitch mm
kN, max kN, min kN, min
M3 × 0.5 5.03 2.94 2.21 2.82
M4 × 0.7 8.78 5.14 3.86 4.92
M5 × 0.8 14.2 8.30 6.24 7.94
M6 × 1.0 20.1 11.8 8.9 11.3
M8 × 1.25 36.6 21.4 16.1 20.5
M10 × 1.5 58.0 33.9 25.5 32.5
M12 × 1.75 84.3 49.3 37.1 47.2
M14 × 2.0 115.0 67.5 50.8 64.6
M16 × 2.0 157.0 91.7 68.9 87.7
M20 × 2.5 245.0 143 108 137
10.2.1 The surface discontinuities for these products shall
FIG. 1 Head Discontinuities (See 10.2.1)
conform to Specification F788/F788M and the additional
limitations specified herein.
10.2.1.1 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 permis-
sible provided those located in the bearing area, fillet, and top
surfaces shall not have a depth exceeding 0.03 D or 0.13 mm,
whichever is greater. For peripheral discontinuities, the maxi-
mum depth may be 0.06 D (see Fig. 1).
10.2.1.2 Forging defects located in the socket wall within
0.1timestheactualkeyengagement, T,fromthebottomofthe
FIG. 2 Socket Discontinuities (See 10.2.1)
socketarenotpermissible.Discontinuitieslocatedelsewherein
the socket shall not have a length exceeding 0.25 T,ora
beneath the root of the thread and across the crests of the
maximum depth of 0.03 D not to exceed 0.13 mm (see Fig. 2).
threads are acceptable within the limits of 10.2.1.3.
10.2.1.3 Seamsintheshankshallnotexceedadepthof0.03
D or 0.2 mm, whichever is greater.
11. Number of Tests
10.2.1.4 No transverse discontinuities shall be permitted in
the head-to-shank fillet area. 11.1 The requirements of this specification shall be met in
10.2.1.5 Threads shall have no laps at the root or on the continuous mass production for stock and the manufacturer
flanks,asshowninFig.3.Lapsarepermittedatthecrests(Fig. shall make sample inspection to ensure that the product
3(c))thatdonotexceed25%ofthebasicthreaddepth,andon conforms to the specified requirements. Additional tests of
theflanksoutsidethepitchcylinder.Longitudinalseamsrolled individual shipments of fasteners are not ordinarily necessary.
F879M−02a (2008)
FIG. 3 Thread Discontinuities
A record of the individual heat of steel in each lot shall be 11.4.1 Unless otherwise specified, inspection for corrosion
maintained. The containers shall be coded to permit identifi- resistance shall be in accordance with the manufacturer’s
cation of the lot. standard quality control practices. No specific method of
inspection is required but the screws shall be produced from
11.2 Whenspecifiedinthepurchaseorder,themanufacturer
suitable raw material and manufactured by properly controlled
shall furnish a test report of the last complete set of chemical
practices to maintain resistance to corrosion. When corrosion
analysis and mechanical tests for each stock size in each
tests are required, Supplementary Requirement S4 must be
shipment.
specified in the inquiry and order, except as noted in 11.4.2.
11.3 When tests of individual shipments are required,
11.4.2 Products that have been hot worked shall be solution
Supplementary Requirement S1 must be specified in the
annealed and tested to determine freedom from precipitated
inquiry and order.
carbides. Not less than one corrosion test shall be made from
11.3.1 When the purchaser does not specify the sampling
eachlot.Corrosiontestsshallbeperformedinaccordancewith
plan and basis of acceptance, the following shall apply:
Practices A262, Practices A or E as applicable.
11.3.1.1 The lot, for purposes of selecting samples, shall
12. Test Methods
consist of all products offered for inspection and testing at one
time, that are of the same type, style, nominal diameter, thread
12.1 Chemical Analysis—The chemical composition shall
pitch, nominal length, material, property class, and surface
be determined in accordance with Test Method A751.
finish.
12.1.1 The fastener manufacturer may accept the chemical
11.3.1.2 From each lot, samples shall be selected at random
analysisofeachheatofrawmaterialpurchasedandreportedon
and tested for each requirement in accordance with the
the raw material certification furnished by the raw material
following:
producer. The fastener m
...
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:F 879M–02 Designation: F 879M – 02a (Reapproved 2008)
Standard Specification for
Stainless Steel Socket Button and Flat Countersunk Head
Cap Screws [Metric](Metric)
This standard is issued under the fixed designation F 879M; 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.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope
1.1 This specification covers the chemical and mechanical requirements for stainless steel metric hexagon socket button
(SBHCS) and flat countersunk (SFHCS) head cap screws with nominal thread M 3 through M 20 intended for use in applications
requiring general corrosion resistance.
1.2Two property classes are covered:
1.2.1Austenitic Class A1-50 in an annealed condition at 500 MPa minimum, and
1.2.2Austenitic Class A1-70 in a cold-worked condition at 700 MPa minimum.
1.3
1.2 The following three property classes are covered:
1.2.1 Austenitic Class A 1-50 in an annealed condition at 585 MPa maximum,
1.2.2 Austenitic Class A1–55 in a cold worked condition at 550 MPa minimum, and
1.2.3 Austenitic Class A 1-70 in a cold-worked condition at 700 MPa minimum.
1.3 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this
standard.
1.4 The following hazard caveat pertains only to Section 12, Test Methods: This standard does not purport to address all of the
safety problems, 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:
A 262 Practices for Detecting Susceptibility to Intergranular Attack in Austenitic Stainless Steels
A342 342/A 342M Test Methods for Permeability of Feebly Magnetic Materials
A 380 Practice for Cleaning, Descaling, and Passivation of Stainless Steel Parts, Equipment, and Systems
A 555/A 555M Specification for General Requirements for Stainless Steel Wire and Wire Rods
A 751 Test Methods, Practices, and Terminology for Chemical Analysis of Steel Products
A 967 Specification for Chemical Passivation Treatments for Stainless Steel Parts
D 3951 Practice for Commercial Packaging
E 18 Test Methods for Rockwell Hardness of Metallic Materials
E 92 Test Method for Vickers Hardness of Metallic Materials
E 384 Test Method for Microindentation Hardness of Materials
F 606M Test Methods for Determining the Mechanical Properties of Externally and Internally Threaded Fasteners, Washers,
and Rivets [Metric] (Metric)
F 738M Specification for Stainless Steel Metric Bolts, Screws, and Studs
F 788/F 788M Specification for Surface Discontinuities of Bolts, Screws, and Studs, Inch and Metric Series
F 1470 Guide for Fastener Sampling for Specified Mechanical Properties and Performance Inspection
2.2 ASME Standards:
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 June 10, 2002. Published June 2002. Originally published as F879–84. Last previous edition F879–01.
Current edition approved May 1, 2008. Published August 2008. Originally approved in 1984. Last previous edition approved in 2002 as F 879 – 02a.
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
, Vol 01.03.volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F 879M – 02a (2008)
B 18.3.4M Hexagon Socket Button Head Cap Screws (Metric Series)
B 18.3.5M Hexagon Socket Flat Countersunk Head Cap Screws (Metric Series)
3. Classification
3.1 The designation of the property class and conditions of this specification shall be consistent with the stainless steel
designations in Specification F 738M.
3.2The austenitic stainless steel socket screw shall be designated F879M A1-50 or F879M A1-70.
3.2 The austenitic stainless steel socket screw shall be designated F879M A1-50, F879M A1–55, or F 879M A1-70.
4. Ordering Information
4.1 Orders for material under this specification shall include the following information:
4.1.1 Quantity (number of pieces of each item).
4.1.2 Name of the screw, SBHCS or SFHCS.
4.1.3 Dimensions, including nominal thread designation, thread pitch, and nominal screw length (millimetres).Astandard part
number may be used for this definition.
4.1.4Property Class A1-50 or A1-70.
4.1.4 Property Class A 1-50, A1–55, or A 1-70.
4.1.5 Certification, if required (see Section 15).
4.1.6 ASTM specification and year of issue.
4.1.7 Any special or supplemental requirements (see Supplementary Requirements S1 through S3).
5. Materials and Manufacture
5.1 Screws shall be formed by upsetting or extruding, or both.
5.2 Screws shall be roll threaded.
5.3 Heat Treatment—Austenitic alloys Class A 1-50 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, then cooled at a rate sufficient to prevent precipitation of the carbide and provide the properties specified in Table 1.
5.4 When ConditionProperty Class A1-55 or A1-70 is specified, the austenitic alloys shall be annealed as specified in 5.3,
generally by the raw material manufacturer, then cold worked to develop specific properties.
6. Chemical Composition
6.1 It is the intent of this specification that screws shall be ordered by property class. The chemical composition of the screws
shall conform to the requirements of Table 2.
6.2 Unless otherwise specified in the inquiry and purchase order (see Supplementary Requirement S2) when A1-50 or A1-70
property class is specified,S2), the choice of stainless steel used shall be that of the fastener manufacturer as determined by his
fabrication methods and material availability. The specific stainless steel used by the manufacturer shall be clearly identified on
all certification required in the purchase order and shall have a chemical composition conforming to the limits specified in Table
2.
Annual Book of ASTM Standards, Vol 03.04.
Available from Global Engineering Documents, 15 Inverness Way, East Englewood, CO 80112-5704, http://www.global.ihs.com.
TABLE 1 Mechanical Property Requirements
Full Size
B
Machined Specimen Tests Core Hardness
Product Tests
Nominal Thread
Property Class
A
Minimum
Diameter
Tensile Tensile Yield Strength, Elongation,
Extension, Vickers Rockwell
Strength, MPa Strength, MPa MPa %, min
AC
min
min max min max
max
A1-50 585 max 0.6D 585 max 350 max 40 220
A1-50 M3–M20 585 max 0.6D 585 max 380 max 40 210 max 220
M3-M14A 1-70 525 min 0.4D 600 min 300 min 20 190 330B96 C33
A1–55 M3–M20 550 min 0.4D 550 min 270 min 25 160 min 50B96 C33 HRA min
M16-M20A 1-70 440 min 0.4D 550 min 270 min 25 160 310 B83
A1–70 M3–M20 700 min 0.4D 600 min 450 min 20 220 min 310 B83
A
Actual full-size testing of Class A1–55 and A1–70 may result in decreased tensile strength because of the head configuration (see Table 3). For fasteners with nominal
thread diameters 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.
F 879M – 02a (2008)
TABLE 2 Chemical Requirements
Composition, % maximum except as shown
Property UNS
Alloy
Class Designation
Carbon Manganese Phosphorus Sulfur Silicon Chromium Nickel Copper Molybdenum
Austenitic Alloys
S30400 304 0.08 2.00 0.045 0.030 1.00 18.0 to 20.0 8.0 to 10.5 1.00
S30400 304 0.08 2.00 0.045 0.030 1.00 18.0 to 20.0 8.0 to 10.5 1.00 .
S30403 304L 0.030 2.00 0.045 0.030 1.00 18.0 to 20.0 8.0 to 12.0 1.00
S30403 304L 0.030 2.00 0.045 0.030 1.00 18.0 to 20.0 8.0 to 12.0 1.00 .
A1–50 S30500 305 0.12 2.00 0.045 0.030 1.00 17.0 to 19.0 10.5 to 13.0 1.00
A1–50 S30500 305 0.12 2.00 0.045 0.030 1.00 17.0 to 19.0 10.5 to 13.0 1.00 .
A1–70 S38400 384 0.08 2.00 0.045 0.030 1.00 15.0 to 17.0 17.0 to 19.0 . . .
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
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 .
S30433 302HQ 0.03 2.00 0.045 0.030 1.00 17.0 to 19.0 8.0 to 10.0 3.0to4.0
S30433 302HQ 0.03 2.00 0.045 0.030 1.00 17.0 to 19.0 8.0 to 10.0 3.0to4.0 .
S31600 316 0.08 2.00 0.045 0.030 1.00 16.0 to 18.0 10.0 to 14.0 2.00 to 3.00
S31603 316L 0.03 2.00 0.045 0.030 1.00 16.0 to 18.0 10.0 to 14.0 2.00 to 3.0
6.3 When chemical analysis is performed by the purchaser using finished fasteners, the chemical composition obtained shall
conform to the limits specified in Table 2 for the specific alloy. Chemical composition shall conform to the tolerances specified
in Specification A 555/A 555M.
6.3.1 Intheeventofadiscrepancy,arefereeanalysisofthesamplesforeachlotasspecifiedin12.1,shallbemadeinaccordance
with 11.3.
7. Mechanical Properties
7.1 The finished screws shall conform to the mechanical requirements specified in Table 1.
7.2 Screws having a nominal length equal to or greater than three diameters shall be tensile tested full size and shall meet the
full size breaking strength requirements specified in Table 3. Tensile failures through the head are acceptable providing the load
requirements are satisfied.
7.3 Screws that are too short (lengths less than specified in 7.2 or that have insufficient threads for tension testing) shall not be
subject to tension tests, but shall conform to the maximum and minimum hardness requirements of Table 1.
8. Corrosion Resistance Requirements Corrosion Resistance Requirements
8.1 Carbide Precipitation:
8.1.1 Austenitic alloy rod, bar, and wire 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 Practice A 262.
8.1.2 As stated in Practices A 262, 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.
8.1.3 If the fasteners pass the requirements of 8.1.1, they shall be considered acceptable. If they fail, they shall be tested in
accordance with Practice C of Practices A 262 and shall show a corrosion rate not exceeding 0.05 mm/month.
9. Dimensions
9.1 Unless otherwise specified, the dimensions shall conform to the requirements of ASME B 18.3.4M or ASME B 18.3.5M,
as specified.
10. Workmanship, Finish, and Appearance
10.1 Surface Treatment—Unless otherwise specified, screws shall be cleaned, descaled and passivated in accordance with
Practice A380 or Specification A 967 at the option of the manufacturer.
10.2 Surface Discontinuities:
10.2.1 The surface discontinuities for these products shall conform to Specification F 788/F 788M and the additional limitations
specified herein.
10.2.1.1 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 mm, whichever is greater.
For peripheral discontinuities, the maximum depth may be 0.06 D (see Fig. 1).
10.2.1.2 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).
10.2.1.3 Seams in the shank shall not exceed a depth of 0.03 D or 0.2 mm, whichever is greater.
F 879M – 02a (2008)
TABLE 3 Breaking Strength Values for Full Size Fasteners
NOTE 1—Breaking loads are based on tensile stress area and strengths
of 585 MPa max forA1-50 and 525 MPa min through M14 and 440 MPa
min for A1-70. The minimum loads for class A1-70 are based on the
tensilepropertiesof655MPamaterialstrengththroughM14and550MPa
material strength M16 and above, reduced by 20 % to allow for the head
critical nature of these configurations.Table 1. Actual strength of the
threadedsection,ifsizepermits,maybedeterminedbyremovingthehead
and testing the threaded section as a stud.
Property Class
Alloy Class
Nominal Size and Stress Area, Alloy Class
A1–50 A1-–50
Thread Pitch mm A1-–70
kN, max kN, min kN, min
M3 3 0.5 5.03 2.94 2.64
M3 3 0.5 5.03 2.94 2.21 2.82
M4 3 0.7 8.78 5.13 4.61
M4 3 0.7 8.78 5.14 3.86 4.92
M5 3 0.8 14.2 8.31 7.46
M5 3 0.8 14.2 8.30 6.24 7.94
M6 3 1.0 20.1 11.8 10.6
M6 3 1.0 20.1 11.8 8.9 11.3
M8 3 1.25 36.6 21.4 19.2
M8 3 1.25 36.6 21.4 16.1 20.5
M10 3 1.5 58.0 33.9 30.5
M10 3 1.5 58.0 33.9 25.5 32.5
M12 3 1.75 84.3 49.3 44.3
M12 3 1.75 84.3 49.3 37.1 47.2
M14 3 2.0 115.0 67.3 60.4
M14 3 2.0 115.0 67.5 50.8 64.6
M16 3 2.0 157.0 91.9 69.1
M16 3 2.0 157.0 91.7 68.9 87.7
M20 3 2.5 245.0 143.0 108.0
M20 3 2.5 245.0 143 108 137
FIG. 1 Head Discontinuities (See 10.2.1)
F 879M – 02a (2008)
FIG. 2 Socket Discontinuities (See 10.2.1)
10.2.1.4 No transverse discontinuities shall be permitted in the head-to-shank fillet area.
10.2.1.5 Threads shall have no laps at the root or on the flanks, as shown in Fig. 3. Laps are permitted at the crests (Fig. 3(c))
that do not exceed 25 % of the basic thread depth, and on the flanks outside the pitch cylinder. Longitudinal seams rolled beneath
the root of the thread and across the crests of the threads are acceptable within the limits of 10.2.1.3.
11. Number of Tests
11.1 The requirements of this specification shall be met in continuous mass production for stock and the manufacturer shall
make sample inspection to ensure that the product conforms to the specified requirements.Additional tests o
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