Standard Specification for Surface Discontinuities of Bolts, Screws, and Studs, Inch and Metric Series

SCOPE
1.1 This specification establishes allowable limits for the various types of surface discontinuities that may occur during the manufacture and processing of bolts, screws, and studs, including heat-treated machine screws, tapping screws, and sems (the washers of screw-washer assemblies are excluded). This specification covers metric series products with nominal diameters of 4 mm and larger and with specified minimum tensile strengths of 800 MPa and greater; and inch series products with nominal diameters of No. 5 (0.1250 in.) and larger and with specified minimum tensile strengths of 90000 psi and greater.
1.2 The values stated in either SI (metric) or inch-pound units are to be regarded separately as standard. The values stated in each system are not exact equivalents, therefore, each system must be used independently of the other. Combining values from the two systems may result in nonconformance with the specification.
1.3 When the engineering requirements of the application necessitate control of surface discontinuities on bolts, screws, or studs, the purchaser shall specify conformance to ASTM Specification F 788/F 788M, in the original inquiry and purchase order.
1.3.1 When the engineering requirements of the application necessitate that surface discontinuities on bolts, screws, and studs be controlled within limits closer than those specified in this specification, the purchaser shall specify the applicable limits in the original inquiry and purchase order.
1.4 The allowable limits established in this specification for metric bolts, screws, and studs with nominal diameters from 4 to 24 mm inclusive, are essentially identical with requirements given in ISO 6157/I. There are no ISO standards for surface discontinuities on any inch-series products.

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ASTM F788/F788M-02 - Standard Specification for Surface Discontinuities of Bolts, Screws, and Studs, Inch and Metric Series
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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: F 788/F 788M – 02
Standard Specification for
Surface Discontinuities of Bolts, Screws, and Studs, Inch
1
and Metric Series
This standard is issued under the fixed designation F 788/F 788M; the number immediately following the designation indicates the year
of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.
A superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope* 2. Referenced Documents
1.1 This specification establishes allowable limits for the 2.1 ASTM Standards:
2
various types of surface discontinuities that may occur during E 340 Test Method for Macroetching Metals and Alloys
the manufacture and processing of bolts, screws, and studs, F 1470 Standard Guide for Fastener Sampling for Specified
3
including heat-treated machine screws, tapping screws, and Mechanical Properties and Performance Inspection
sems (the washers of screw-washer assemblies are excluded). F 1789 Standard Terminology for F16 Mechanical Fasten-
3
This specification covers metric series products with nominal ers
4
diameters of 4 mm and larger and with specified minimum 2.2 ISO Standard:
tensile strengths of 800 MPa and greater; and inch series ISO 6157/I Fasteners, Surface Discontinuities on Bolts,
products with nominal diameters of No. 5 (0.1250 in.) and Screws and Studs
larger and with specified minimum tensile strengths of 90 000
3. Ordering Information
psi and greater.
3.1 Orders for bolts, screws, and studs requiring disconti-
1.2 The values stated in either SI (metric) or inch-pound
units are to be regarded separately as standard. The values nuity control shall include the following:
3.1.1 ASTM designation and date of issue of this specifica-
stated in each system are not exact equivalents, therefore, each
system must be used independently of the other. Combining tion.
3.1.2 Special requirements, for example, closer discontinu-
values from the two systems may result in nonconformance
with the specification. ity limits (1.3.1) and inspection sampling plan (6.2).
1.3 When the engineering requirements of the application
4. Types of Surface Discontinuities (see Terminology
necessitate control of surface discontinuities on bolts, screws,
F 1789 for definitions not provided)
or studs, the purchaser shall specify conformance to ASTM
4.1 Crack
Specification F 788/F 788M, in the original inquiry and pur-
4.1.1 Quench Cracks—Typical quench cracks are shown in
chase order.
Fig. 1. Limits are specified in 5.2.
1.3.1 When the engineering requirements of the application
4.1.2 Forging Cracks—Typical forging cracks are shown in
necessitate that surface discontinuities on bolts, screws, and
Fig. 2. Limits are specified in 5.3.
studs be controlled within limits closer than those specified in
4.2 Burst—Typical bursts are shown in Fig. 3. Limits are
this specification, the purchaser shall specify the applicable
specified in 5.4.
limits in the original inquiry and purchase order.
4.2.1 Shear Burst—A shear burst is an open break in the
1.4 The allowable limits established in this specification for
metal located at approximately a 45° angle to the product axis.
metric bolts, screws, and studs with nominal diameters from 4
Shear bursts occur most frequently at the periphery of products
to 24 mm inclusive, are essentially identical with requirements
having flanged or circular heads. Shear bursts may also occur
given in ISO 6157/I. There are no ISO standards for surface
on the sides of hex-head products. Typical shear bursts are
discontinuities on any inch-series products.
shown in Fig. 3. Limits are specified in 5.4.
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This specification is under the jurisdiction of ASTM Committee F16 on
2
Fasteners and is the direct responsibility of Subcommittee F16.93 on Quality Annual Book of ASTM Standards, Vol 03.01.
3
Assurance Provisions for Fasteners. Annual Book of ASTM Standards, Vol 01.08.
4
Current edition approved July 10, 2002. Published August 2002. Originally Available from American National Standards Institute, 11 West 42nd Street,
published as F 788/F 788M – 82. Last previous edition F 788/F 788M – 97. 13th Floor, New York, NY 10036.
*A Summary of Changes section appears at the end of this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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F 788/F 788M – 02
FIG. 1 Typical Quench Cracks
mum) or head diameter (specified maximum) of circular head
products. For metric series products, D and Dc are in millime-
tres; for inch-series products, D and Dc are in inches.
5.2 Quench Cracks—Quench cracks of any depth, any
length, or in any location are not permitted
...

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