GB/T 5780-2025Fasteners - Hexagon head bolts - Product grade C (English PDF)

Foreword

This document was drafted in accordance with the provisions of GB/T 1.1-2020

Directives for standardization - Part 1.Rules for the structure and drafting of

standardizing documents.

This document replaces GB/T 5780-2016 Hexagon head bolts - Product grade C.

Compared with GB/T 5780-2016, apart from structural adjustments and editorial

changes, the main technical changes are as follows.

a) The permissible head shapes have been added, including head indentation and

under-head junction length area lf (see Figure 2).

b) The M7 size has been added (see Table 2).

c) The dw,min value of M5 has been changed from smin-IT16 to smin-IT15 (for

hexagon head bolts of product grades A and B) to obtain a larger bearing area,

thereby reducing contact pressure (see Table 1; see Table 1 of the 2016 edition).

d) Rules for the shortest and longest standard lengths have been added, and the

shortest and longest standard lengths have been adjusted accordingly (see

Figure 1; see Table 1~Table 4).

e) For the size M33×260, the lg,max has been changed from 167 mm to 169 mm

(see Table 3; see Table 2 of the 2016 edition).

f) The technical requirements for hot-dip galvanizing have been added according

to GB/T 5267.3 (see Table 5).

g) Surface defects have been added, and surface defects are in accordance with

GB/T 5779.1 (see Table 5).

h) The marking and labeling have been added (see Chapter 6).

This document is modified in relation to ISO 4016.2022 Fasteners - Hexagon head

bolts - Product grade C.

The technical differences between this document and ISO 4016.2022, and the reasons

therefor, are as follows.

-- The statement in ISO 4016, "If in certain cases other specifications are requested,

property classes can be selected from ISO 898-1 and dimensional options from

ISO 888 or ISO 4753," (Chapter 1), has been deleted. This content is not part of

the provisions of this document.

Fasteners - Hexagon head bolts - Product grade C

1 Scope

This document specifies the type, dimensions, technical requirements, markings, labels,

and designation for hexagon head bolts of product grade C.

This document applies to steel hexagon head bolts (hereinafter referred to as "bolts")

with thread sizes of M5 to M64, coarse threads, property classes of 4.6 and 4.8, and

product grade of C.

2 Normative references

The provisions of the following documents constitute the essential clauses of this

document through normative references in this text. Among them, for any dated

reference, only the version corresponding to that date applies to this document; for any

undated reference, the latest version (including all amendments) applies to this

document.

GB/T 2 Fasteners - Ends of parts with external thread (GB/T 2-2016, ISO

4753.2011, MOD)

GB/T 90.1 Fasteners - Acceptance inspection (GB/T 90.1-2023, ISO 3269.2019,

MOD)

GB/T 90.2 Fasteners - Marking and packaging

GB/T 197 General purpose metric screw threads - Tolerances (GB/T 197-2018,

ISO 965-1.2013, 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

3098.1-2010, ISO 898-1.2009, MOD)

GB/T 3099.4 Terminology of fasteners - Control, inspection, delivery, acceptance

and quality (GB/T 3099.4-2021, ISO 1891-4.2018, MOD)

GB/T 3103.1 Tolerances for fasteners--Bolts, screws, studs and nuts (GB/T 3103.1-

2002, idt ISO 4759-1.2000)

GB/T 3106 Fasteners - Bolts, screws and studs - Nominal lengths and thread

lengths (GB/T 3106-2016, ISO 888.2012, MOD)

GB/T 5267.1 Fasteners - Electroplate coating (GB/T 5267.1-2023, ISO 4042.2022,

MOD)

GB/T 5267.2 Fasteners - Non-electrolytically applied zinc flake coatings (GB/T

5267.2-2021, ISO 10683.2018, MOD)

GB/T 5267.3 Fasteners - Hot dip galvanized coatings (GB/T 5267.3-2008, idt ISO

10684.2004)

GB/T 5276 Fasteners - Bolts, screws, studs and nuts - Symbols and descriptions of

dimensions (GB/T 5276-2015, ISO 225.2010, MOD)

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 16938 Fasteners - General requirements for bolts, screws, studs and nuts

(GB/T 16938-2008, ISO 8992.2005, IDT)

3 Terms and definitions

This document does not contain any terms or definitions that need to be defined.

4 Types and dimensions

The types of bolts shall be as shown in Figures 1 and 2, and the dimensions shall be as

shown in Table 1~Table 4.

Symbols and descriptions of dimensions shall conform to GB/T 5276.

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