BS EN ISO 3506-4:2009 Mechanical properties of corrosion-resistant stainless steel fasteners. Tapping screws
BS EN ISO 3506-4 specifies the mechanical properties of tapping screws made of austenitic, martensitic and ferritic steel grades of corrosion-resistant stainless steels, when tested over an ambient temperature range of 10 °C to 35 °C. Properties vary at higher or lower temperatures.
It applies to tapping screws with threads from ST2,2 up to and including ST8, in accordance with ISO 1478.
It does not apply to screws with special properties, such as weldability.
The aim of BS EN ISO 3506-4 is the classification of corrosion-resistant stainless steel tapping screws into hardness classes. Corrosion and oxidation performances and mechanical properties for use at elevated or sub-zero temperatures can be agreed on between the user and the manufacturer in each particular case. Annex D shows how the risk of intergranular corrosion at elevated temperatures depends on the carbon content.
All austenitic stainless steel fasteners are normally non-magnetic in the annealed condition; after cold working, some magnetic properties can be evident.
Contents of BS EN ISO 3506-4:
Foreword
Introduction
1 Scope
2 Normative references
3 Designation, marking and finish
3.1 Designation
3.2 Marking
3.3 Finish
4 Chemical composition
5 Mechanical properties
5.1 General
5.2 Surface hardness
5.3 Core hardness
5.4 Torsional strength
5.5 Thread forming capability
6 Test methods
6.1 Surface hardness test
6.2 Core hardness test
6.3 Torsional strength test
6.4 Drive test
Annex A (normative) Description of the groups and grades of stainless steels
Annex B (informative) Stainless steel for cold heading and extruding
Annex C (informative) Austenitic stainless steels with particular resistance to chloride induced stress corrosion
Annex D (informative) Time-temperature diagram of intergranular corrosion in austenitic stainless steels, grade A2 (18/8 steels
Annex E (informative) Magnetic properties for austenitic stainless steels
Bibliography
