Abstract: A method of making a low distortion frame construction, the construction having joint regions formed by first and second overlapping members defining a lapped interface, the joint regions being comprised of material that can be converted to a solid state deformable plastic condition by friction heat, comprising: (a) providing a stir friction welding tool having (i) a rotatable thermally conductive body presenting a shoulder to engage the joint region for storing friction-generated heat, and (ii) a friction generating pin rotatable with said body about a pin axis and selectively extendable from the shoulder to progressively penetrate the overlapping members as the joint region in contact with the pin becomes plastic; (b) placing the tool shoulder against the joint region with the pin axis transverse to the lapped interface and spinning the body while progressively extending the pin at a rotational speed effective to generate friction heat that converts the adjacent material of the joint to a plastic condition

Abstract: Method of one side spot welding of a metallic auto body construction containing vaporizable coatings or ingredients, the construction having overlapping metal plys, comprising: impinging a plasma column on a selected spot of one side of the construction, the plasma column being generated by passing a plasma gas at a predetermined flow rate through an electrical arc created by a predetermined electrical current path; shielding the plasma column in an inert gas containing at least 5-35% by volume of oxygen, the shielded plasma column melting at least the metal on one ply at the spot while the oxygen increases the fluidity and wetablility of the melted metal and reduce its surface tension allowing any vaporization of the ingredients to quiescently escape through the molten metal; and ceasing plasma arc impingement for allowing the molten metal to solidify and complete the spot weld.