Material bulge in rolled screw 12.9
Chemical designation | Schraube 12.9 |
---|---|
State | rolled screw with Material bulge |
Etching | 3 % Nital |
The screw was quenched and tempered after the thread was rolled, therefore, the deformation can only be recognized by the bulges in the profile. The bulge in the tip makes 1/3 of the thread height up and is not permissible, since according to DIN EN 26157-3, bulges in the thread tip may only amount to a maximum of a quarter of the height. The edge decarburization at the thread tip also extends along the bulg.