By doing so, weld current and force is focused into the small area of the projection, and heat is obtained from the resistance to the flow of the welding current. Due to this heat, the projections collapse and the parts are weld together. Another successful welding technique is capacitor discharge stud welding, which uses weld studs or specially formed bolts for welding instead of projections.
Definition of inert. 1  1 : lacking the power to move. 2  2 : very slow to move or act : sluggish. 3  3 : deficient in active properties; especially : lacking a usual or anticipated chemical or biological action.
An inert gas is any gas that is not reactive with elements. Like the noble gases an inert gas is not necessarily elemental and are often compound gases. Like the noble gases the tendency for non-reactivity is due to the valence, the outermost electron shell, being complete in all the inert gases.