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Conductive heat resistance seam welding (CHRSEW) is a new process developed at Edison Welding Institute for creating butt joints on aluminum sheet. The process uses conventional resistance seam welding equipment, and takes advantage of steel cover sheets on either side of the intended joint. Resulting joints are fusion in character, and can be manufactured at very high welding speeds (∼ 3 to 4 m/min). In this study, the conductive heat resistance seam welding process was extended to some new applications. These included joining a 7075-T6 alloy, and a dissimilar thickness 1- to 2-mm 5754 configuration. The former is generally considered unweldable by fusion methods, and is of considerable interest for aerospace applications. The latter is representative of a tailor welded blank for automotive applications. Resulting welds were evaluated using metallurgical examinations and mechanical testing.

Laser welding has long been evaluated as a joining technique for galvanized steels in a lap-joint configuration in the automotive industry. However, a problem associated with the low boiling point of zinc limits the application of the laser process in a lap-joint configuration. Zinc-coatings at the interface of the two coated sheets vaporize during welding and the volume of the zinc vapor expands rapidly. The venting of the zinc vapor from the weld pool causes expulsion of the molten metal during welding and a portion of zinc vapor remains in the weld as porosity after welding. To improve the weld quality of galvanized steel, many efforts have been attempted worldwide, but limited success has been reported. Edison Welding Institute (EWI) investigated the laser weldability of galvanized steel in a lap-joint configuration with no gap using a dual beam laser welding technique.

An experimental evaluation to systematically study a hot air cold stake joining process was conducted with injection molded samples. Twelve material combinations consisting of six stud plate materials were matched with two hole plate materials (GDT 6400 and 18% talc filled PP). Seven stud designs with variations in size and geometry were used for each material combination. A proper heating temperature was first determined by heat characterization trials. Different heating times and stake heights were studied in the staking experiments. Pull tests were conducted to determine the strength of the joints and their failure mode. Results showed that material characteristics, material combinations, and process parameters all could contribute to variations in pull strength and different failure modes.