GB/T 70.3-2008 English PDF (GBT70.3-2008)

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GB/T 70.3-2008: Hexagon socket countersunk head screws
GB/T 70.3-2008
ICS 21.060.10
J 13
GB
National Standard
of The People’s Republic of China
Replacing GB/T 70.3-2000
Hexagon socket countersunk head screws
内六角沉头螺钉
(ISO 10642. 2004, MOD)
ISSUE ON. AUGUST 25, 2012
IMPLEMENTED ON. FEBRUARY 1, 2009
Issued by. The General Administration of Quality Supervision, Inspection and
Quarantine of People's Republic of China; and China National
Standardization Management Committee
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative reference documents ... 5
3 Dimensions ... 6
4 Technical conditions and reference standards ... 11
5 Mark ... 12
Foreword
This Part is one of the product (including gauging) series standards of national standard
"Hexagon socket screws". The series include.
- GB/T 70.1-2008 Hexagon socket head cap screws
- GB/T 70.2-2008 Hexagon socket button head screws
- GB/T 70.3-2008 Hexagon socket countersunk head screws
- GB/T 70.4 Hexagon socket cap head screws – Fine thread stud
- GB/T 70.5-2008 Gauging of Hexagon Sockets
- GB/T 77-2007 Hexagon socket set screws with flat point
- GB/T 78-2007 Hexagon socket set screws with cone point
- GB/T 79-2007 Hexagon socket set screws with dog point
- GB/T 80-2007 Hexagon socket set screws with cup point
- GB/T 5281-1985 Hexagon socket head shoulder screws
This Part is part 3 of GB/T 70.
This Part modifies and adopts ISO 10642. 2004 "Hexagon socket countersunk head
screws" (English version), major changes are as follows.
- In reference documents, USE our national standards to replace international
standards (Chapter 2);
- ISO 10642 does not specify the packaging technical requirements, this Part
specified the packaging requirements (see Table 2);
- ISO 10642 does not specify simplified mark, this Part provides simplified mark (see
5.2) according to GB/T 1237.
This Part replaces GB/T 70.3-2000 "Hexagon socket countersunk head screws".
Compared with GB/T 70.3-2000, the major changes of this Part are as follows.
- ADD reference standard GB/T 5267.2 "Fasteners - Non-Electrolytically Applied
Zinc Flake Coatings" and GB/T 70.5 "Gauging of Hexagon Sockets" (Chapter 2);
- DELETE Appendix A.
This Part was proposed by the China Machinery Industry Federation.
This Part shall be administered by the National Fastener Standardization Technical
Committee (SAC/TC85).
Responsible drafting organization of this Part. The Machine Productivity Promotion
Center.
Participating drafting organizations of this Part. Shanghai Biaowu High-strength Fastener
Co., Beijing Standard Part Industry Corporation, Shenyang Standard Part Manufacturing
Plant, and Ningbo Zhongbin Fastener Manufacturing Co., Ltd.
This Part shall be responsibly interpreted by Secretariat of the National Fastener
Standardization Technical Committee.
The previous version of the standard replaced by this Part is.
- GB/T 70.3-2000.
Hexagon socket countersunk head screws
1 Scope
This Part specifies the hexagon socket countersunk head screws with. thread size is
M3~M20; performance grades are 8.8, 10.9, and 12.9; and product grade is A.
NOTE. Special attention shall be paid to the note in Table 2, and to the provisions in Table 3 relating to
tensile load.
If other technical requirements are required, it shall select from existing standards (such as
GB/T 196, GB/T 3106, GB/T 3098.1, and GB/T 3103.1).
2 Normative reference documents
The provisions in following documents become part of this Part, through reference in this
Part. For dated documents, subsequent amendments (excluding corrections) or revisions
shall not apply to this Part. However, all parties who enter into agreement according to this
Part are encouraged to study if the latest versions of these documents are applicable. For
undated documents, the latest version applies to this Part.
GB/T 2 Fasteners - Ends of Parts with External Thread GB/T 2-2001, IDT ISO 4753.
1999)
GB/T 70.5 Gauging of Hexagon Sockets (GB/T 70.5-2008, ISO 23429. 2004, IDT)
GB/T 90.1 Fasteners - Acceptance Inspection (GB/T 90.1-2002, IDT ISO 3269. 2000)
GB/T 90.2 Fasteners - Marking and Packaging
GB/T 196 General Purpose Metric Screw Threads - Basic Dimensions (GB/T
196-2003, ISO 724. 1993, ISO General Purpose Metric Screw Threads-Basic
Dimensions, MOD)
GB/T 197 General Purpose Metric Screw Threads - Tolerances (GB/T 197-2003, ISO
965-1. 1998, ISO General Purpose Metric Screw Threads - Tolerances-Part 1.
Principles and Basic Data, MOD)
GB/T 1237 Designation System for Fasteners (GB/T 1237-2000, eqv ISO 8991. 1986)
GB/T 3098.1 Mechanical Properties of Fasteners - Bolts, Screws and Studs (GB/T
3098.1-2000, IDT ISO 898-1. 1999)
GB/T 3103.1 Tolerances for Fasteners - Bolts, Screws, Studs and Nuts (GB/T
3103.1-2002, ISO 4759-1. 2000, IDT)
GB/T 3106 Bolts, Screws and Studs - Nominal Lengths and Thread Lengths for
General Purpose Bolts [GB/T 3106-1982 (affirmed in 1988), eqv ISO 888. 1976]
GB/T 5267.1 Fasteners - Electroplated Coatings (GB/T 5267.1-2002, ISO 4042. 1999,
IDT)
GB/T 5267.2 Fasteners - Non-Electrolytically Applied Zinc Flake Coatings (GB/T
5267.2-2002, ISO 10683. 2000, IDT)
GB/T 5276 Fasteners; Bolts, Screws, Studs and Nuts - Symbols and Designations of
Dimensions (GB/T 5276-1985, eqv ISO 225. 1983)
GB/T 5779.1 Fasteners - Surface Discontinuities-Bolts, Screws and Studs for General
Requirements (GB/T 5779.1-2000, IDT ISO 6157-1. 1988)
GB/T 5779.3 Fasteners - Surface Discontinuities-Bolts, Screws and Studs for Special
Requirements (GB/T 5779.3-2000, IDT ISO 6157-3. 1988)
GB/T 16938 Fasteners - General Requirements for Blots, Screws, Studs and Nuts
(GB/T 16938-2008, ISO 8839. 2005, IDT)
3 Dimensions
3.1 Dimensions
Type dimensions are shown in Figure 1 and Table 1.
Dimension symbols and marking shall comply with GB/T 5276.
broken, the fracture may occur at part of the thread, the head or the join of head-pole.
Table 3 Minimum tensile loading of hexagon countersunk head screws
(80% of specified value by GB/T 3098.1)
Thread size d
Performance grade
8.8 10.9 12.9
Minimum tensile load / N
M3 3220 4180 4910
M4 5620 7300 8560
M5 9080 11800 13800
M6 12900 16700 19600
M8 23400 30500 35700
M10 37100 48200 56600
M12 53900 70200 82400
M14 73600 96000 112000
M16 100000 130000 154000
M20 162000 204000 239000
5 Mark
5.1 Marking method
Marking method shall be according to the provisions of GB/T 1237.
5.2 Marking example
Marking of hexagon socket countersunk head screws with - thread size d = M12, nominal length l =
40 mm, performance grade is grade 8.8, oxidized surface, and class A.
Screw GB/T 70.3 M12×40