The Influence of Thermal and Mechanical Effects on the Bond Formation During Impact Welding

Impact welding, usually applied as explosion welding or electromagnetic pulse welding, is a highly transient joining process. Strain rates in orders of magnitude far above 104 1/s and resultant thermal effects occur and influence the formation of the joint significantly. Experimental and microscopic investigations as well as analytical estimations are carried out and presented in this paper in order to gain a more comprehensive understanding of the effective mechanisms and their relevance. In addition to electromagnetic pulse welding, a specially built test rig is used to identify the process window and its change due to modified parameters. The test rig allows to change both impact parameters, angle β and velocity v_c , independently. It will be shown that the actual formation of the joint and its characteristics are greatly affected by the surrounding gaseous media. Strength and size of the joint can be influenced as well as the location of the process window. Theories will be developed to explain these results and to make them usable for the practical application. Furthermore, experimental results indicate that the compression of the ambient atmosphere in the closing gap between the two specimens evokes highly elevated temperature, which is in good accordance with earlier findings