In an Assembly document, click Tools tab→Model group→Weldment Assembly
On the Weldment Assembly dialog box, set the Mark This Assembly as a Weldment option.
On the Weldment Assembly dialog box, set the bead options you want, then click OK.
Tip:
When you specify that an assembly document is marked as a weldment, you can add weldment-specific features to the assembly. For example, you can add fillet weld, groove weld, and stitch weld features, and add weld labels to edges on the parts in the assembly.