GB/T 70.6-2020 in English

《GB/T 70.6-2020内六角圆柱头螺钉 细牙螺纹》由TC85（全国紧固件标准化技术委员会）归口，主管部门为中国机械工业联合会。

ChinaStandards.net is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.

GB/T 70 is one of the national standards series of Inner Wrenching Screws (Hexagon Part), which consists of the following standards:

— GB/T 70.1 Hexagon Socket Head Cap Screws;

— GB/T 70.2 Hexagon Socket Button Head Screws;

— GB/T 70.3 Hexagon Socket Countersunk Head Screws;

— GB/T 70.4 Hexagon Socket Button Head Screws with Collar;

— GB/T 70.6 Hexagon Socket Head Cap Screws — Fine Pitch Thread;

— GB/T 5281 Hexagon Socket Head Shoulder Screws.

This part is Part 5 of GB/T 70.

This part is drafted in accordance with the rules given in the GB/T 1.1-2009.

This part has been redrafted and modified adoption of International Standard ISO 12474:2010 Hexagon Socket Head Cap Screws with Metric Fine Pitch Thread.

The technical deviations between this part and ISO 12474:2010, together with their justifications, are as follows:

— In Normative References, international standards are replaced with corresponding national standards of China (see Clause 2); addition of the normative references GB/T 70.5 (see Table 1), GB/T 90.2 (see Table 2) and GB/T 1237 (see 5.1), which are consistent with the basic fastener standards of China;

— addition of the non-ferrous metal CU2 and CU3 (see Table 2) to expand the scope of products used;

— addition of the packaging technical requirements (see Table 2), which is consistent with the basic fastener standards of China;

— modification of the corresponding specification of stainless steel product performance grade to "d ≤ 24 mm" and "24 mm < d ≤ 36 mm” (see Table 2);
— for the purpose of comply with the requirements of GB/T 1237, modification of the designation example to the simplified designation example (see 5.2);

— deletion of the “If specifications other than those listed in this International Standard are required, they should be selected from existing International Standards, for example ISO 261, ISO 888, ISO 898-1, ISO 965-2, ISO 3506-1, ISO 4759-1 and ISO 8839.” in Clause 6 Other Specification of ISO 12474:2010, , which are not included in this part.

For the purposes of this part, the following editorial changes have also been made:

— modification of the standard name;

— deletion of the bibliography of ISO 12474:2010.

This part was proposed by China Machinery Industry Federation.

This part is under the jurisdiction of SAC/TC 85 (National Technical Committee 85 on Fasteners of Standardization Administration of China).

The explanation of this part is in the charge of the National Technical Committee 85 on Fasteners of Standardization Administration of China.


Hexagon Socket Head Cap Screws — Fine Pitch Thread


1 Scope

This part of GB/T 70 specifies the types and dimensions, specifications and designations of hexagon socket head cap screws with fine pitch thread.

This part is applicable to the hexagon socket head cap screws with fine pitch thread with nominal thread diameters, d, from 8 mm up to 36 mm, with property classes 8.8, 10.9, 12.9/12.9, A2-50, A2-70, A3-50, A3-70, A4-50, A4-70, A5-50, A5-70, CU2 and CU3 and product grade A.

For approximate masses of screws, see Annex A.

2 Normative References

The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

GB/T 2 Fasteners — Ends of Parts with External Thread (GB/T 2-2016, ISO 4753:2011, MOD)
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 193 General Purpose Metric Screw Threads — General Plan (GB/T 193-2003, ISO 261:1998, MOD)
GB/T 1237 Designation System for Fasteners (GB/T 1237-2000, eqv ISO 8991:1986)
GB/T 2516 General Purpose Metric Screw Threads — Limit Deviations (GB/T 2516-2003, ISO 965-3:1998, MOD)
GB/T 3098.1 Mechanical Properties of Fasteners — Bolts, Screws and Studs (GB/T 3098.1-2010, ISO 898-1:2009, MOD)
GB/T 3098.6 Mechanical Properties of Fasteners — Stainless Steel Bolts, Screws and Studs (GB/T 3098.6-2014, ISO 3506-1:2009, MOD)
GB/T 3098.10 Mechanical Properties of Fasteners — Bolts, Screws, Studs and Nuts Made of Non-ferrous Metals (GB/T 3098.10-1993, eqv ISO 8839:1986)
GB/T 3103.1 Tolerances for Fasteners — Bolts, Screws, Studs and Nuts (GB/T 3103.1-2002, idt ISO 4759-1:2000)
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 5267.2-2017, ISO 10683:2014, MOD)
GB/T 5267.4 Passivation of Corrosion-resistant Stainless-steel Fasteners (GB/T 5267.4-2009, ISO 16048:2003, IDT)
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 5779.3 Fasteners — Surface Discontinuities — Bolts, Screws and Studs for Special Requirements (GB/T 5779.3-2000, idt ISO 6157-3:1988)
GB/T 9145 General Purpose Metric Screw Threads — Limits of Sizes for the Screw Threads of Medium Quality and Preferable Plan (GB/T 9145-2003, ISO 965-2:1998, MOD)
GB/T 16938 Fasteners — General Requirements for Bolts Screws Studs and Nuts (GB/T 16938-2008, ISO 8992:2005, IDT)

3 Types and Dimensions

See Figure 1 and Table 1 for the types and dimensions of screws.

Symbols and descriptions of dimensions are specified in GB/T 5276.

Foreword II
1 Scope
2 Normative References
3 Types and Dimensions
4 Technical Requirements and Reference Standards
5 Designation
Annex A (Informative) Masses of Steel Screws