GB/T 3098.5-2025Mechanical properties of fasteners - Part 5: Tapping screws (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 is Part 5 of GB/T 3098 Mechanical properties of fasteners. GB/T 3098

has already published the following parts.

-- GB/T 3098.1 Mechanical properties of fasteners - Bolts, screws and studs.

-- GB/T 3098.2 Mechanical properties of fasteners - Part 2.Nuts.

-- GB/T 3098.3 Mechanical properties of fasteners - Set screws.

-- GB/T 3098.5 Mechanical properties of fasteners - Part 5.Tapping screws.

-- GB/T 3098.6 Mechanical properties of fasteners - Stainless steel bolts, screws

and studs.

-- GB/T 3098.7 Mechanical properties of fasteners - Thread rolling screws.

-- GB/T 3098.8 Mechanical properties of fasteners - Parts for bolted connections

for use at temperatures from -200 °C~+700 °C.

-- GB/T 3098.9 Mechanical properties of fasteners - Prevailing torque type steel

nuts.

-- GB/T 3098.10 Mechanical properties of fasteners - Bolts, screws, studs and nuts

made of non-ferrous metals.

-- GB/T 3098.11 Mechanical properties of fasteners - Drilling screws with tapping

screw thread.

-- GB/T 3098.12 Mechanical properties of fasteners - Cone proof load test on nuts.

-- GB/T 3098.13 Mechanical properties of fasteners - Torsional test and minimum

torques for bolts and screws with nominal diameters from 1 mm to 10 mm.

-- GB/T 3098.14 Mechanical properties of fasteners - Widening test on nuts.

-- GB/T 3098.15 Mechanical properties of fasteners - Stainless steel nuts.

-- GB/T 3098.16 Mechanical properties of fasteners - Stainless steel set screws.

-- GB/T 3098.17 Mechanical properties of fasteners - Preloading test for the

detection of hydrogen embrittlement - Parallel bearing surface method.

Mechanical properties of fasteners - Part 5.Tapping screws

1 Scope

This document specifies the requirements for materials, mechanical and physical

properties, test methods, inspection, marking and labeling of tapping screws when

tested under ambient temperatures of 10 °C~35 °C.

This document applies to tapping screws made of carburized steel with thread

specifications of ST 2.2~ST 9.5 and threads conforming to GB/T 5280.

Tapping screws are used to create mating threads in metal sheets without deforming

their own threads. Tapping screws are not intended for preload conditions, although

they can withstand low levels of tensile stress after installation.

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 3099.4 Terminology of fasteners - Control, inspection, delivery, acceptance

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

GB/T 4340.1 Metallic materials - Vickers hardness test - Part 1.Test method (GB/T

4340.1-2024, ISO 6507-1.2023, MOD)

GB/T 5280 Tapping screws thread (GB/T 5280-2002, idt ISO1478.1999)

GB/T 39310 Fasteners - Types of inspection documents (GB/T 39310-2020, ISO

16228.2017, MOD)

3 Terms and definitions

The following terms and definitions apply to this document.

3.1

tapping screw

sheet metal screw

Screws with threads conforming to GB/T 5280 form mating threads on the material of

the clamped part (usually a thin metal sheet) when screwed into the bottom hole without

deforming their own threads.

4 Materials

Tapping screws shall be made of cold-heading steel that can be surface carburized (e.g.,

GB/T 6478, ISO 4954, EN 10263-3, ASME B18.6.3, JIS G 3507).

5 Mechanical and physical properties

10 °C~35 °C, tapping screws shall meet the mechanical and physical properties

specified in Chapter 5, as shown in Table 1.

The requirements of this chapter shall apply to tapping screws delivered by the supplier,

i.e., without changes to the delivery conditions. If the buyer makes changes or further

processing, the buyer shall be responsible for all changes in consistency of

characteristics caused by the changes or processing.

Table 1 -- Section numbers for mechanical and physical properties and related

test methods

Performance and clause Clause of the test method

Materials 4 --

Surface hardness 5.2 6.2

Depth of carburized layer 5.3 6.3

Core hardness 5.4 6.4

Microstructure 5.5 6.5

Screwing-in performance 5.6 6.6

Torsional strength 5.7 6.7

Ductility a 5.8 6.8

a It is only used as a routine test for process control.

6 Test methods