This part of ISO 3506 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.
| Stael group |
Steel grade |
Chemical Composition,a mass fraction, % | Footnotes | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| c | Si | Mn | p | s | Cr | Mo | Ni | Cu | |||
| Austenitic | A2 | 0.10 | 1 | 2 | 0.05 | 003 | 15 to 20 | _b | 8 to 19 | 4 | od |
| A3 | 0.08 | 1 | 2 | 0.045 | 003 | 17 to 19 | _b | 9 to 12 | 1 | e | |
| A4 | 0.08 | 1 | 2 | 0.045 | 003 | 16 to 18.5 | 2 to 3 | 10 to 15 | 4 | df | |
| AS | 0.08 | 1 | 2 | 0.045 | 003 | 16 to 18.5 | 2 to 3 | 10,5 to 14 | 1 | ef | |
| Martensitic | C1 | 0,09 to 0.15 | 1 | 1 | 0.05 | 003 | 11,5 to 14 | - | 1 | - | f |
| C3 | 0,17 to 0.25 | 1 | 1 | 0.04 | 003 | 16 to 18 | - | 1,5 to 2,5 | - | - | |
| Ferritic | F1 | 0.12 | 1 | 1 | 0.04 | 003 | 15 to 18 | _g | 1 | - | hi |
a. Values are maximum, unless otherwise indicated.
b. Molybdenum may be present at the discretion of the manufacturer. However, if for some applications limiting of the molybdenum
content is essential, this shall be stated at the time of ordering by the purchaser.
c. If the chromium content is below 17 %, the minimum nickel content should be 12 %.
d. For austenitic stainless steels having a maximum carbon content of 0,03 %, nitrogen may be present to a maximum of 0,22 %.
e. This shall contain titanium W 5 × C up to 0,8 % maximum for stabilization and be marked appropriately as specified in this table, or
shall contain niobium (columbium) and/or tantalum W 10 × C up to 1,0 % maximum for stabilization and be marked appropriately as
specified in this table.
f.
At the discretion of the manufacturer, the carbon content may be higher where required in order to obtain the specified mechanical
properties at larger diameters, but shall not exceed 0,12 % for austenitic steels.
g. Molybdenum may be present at the discretion of the manufacturer.
h. This may contain titanium W 5 × C up to 0,8 % maximum.
i.
This may contain niobium (columbium) and/or tantalum W 10 × C up to 1 % maximum.