The effect of surface oxides on the properties of welded joints in different methods of surface preparation and parameters of pressure welding

摘要

In the examination of different conditions of pressure welding, which determine the quality of welded joints (welding deformation and welding temperature, the duration and rate of welding deformation, etc), a special role is played by the condition of the contacting surfaces. In this case, it is important to stress the significance of the surface finish of preliminary treatment of the surfaces which determines the relief of the surfaces and, consequently, the area of physical contact of the welded joints. The factor of the condition of the welded surfaces, associated with the presence of oxide films on the surface, is also very important or even controlling. In order to reduce the negative effect of these films, it is necessary to use different methods of cleaning the surface to remove oxides, in particular, deformation of the metal in the welding zone, which should remove the surface oxides. Possibly, for the conditions of cold welding, in which welding strains usually equal at least 70-80 percent, the high-intensity plastic flow of the metal in the welding zone is sufficient for fracturing strong oxide films in the contacting surfaces and displacing them into the flash. This results in the formation of clean surfaces with no oxide films. However, in other welding methods, in which the welding deformation is not so high, the cleaning of the welded surfaces to remove all of the oxides is associated with difficulties.