| 摘要 |
The invention relates to a screw having a head, an adjoining retaining section and a functional tip for use as a self-tapping screw. The functional tip is of greater hardness than the retaining section. The entire screw is made of hardened low-alloy carbon steel. The special feature of this screw is that its functional tip has a higher carbon and/or nitrogen content than its retaining section. |
