The fatigue properties of welded components can be improved by means of post-weld treatments, like TIG dressing or hammering. This article describes the results obtained in the research project “DURIMPROVE”, in which the effects of post-weld treatments on welds in high strength steel were investigated.
The main objective is to investigate and develop a non-destructive quality control for friction spot welds by using acoustic emission monitoring. The influence of several welding parameters on the acoustic emission result was investigated and a standard setup with a minimum of background noise was developed. To get a better understanding of the acoustic emission technique, a second welding technique namely MIG/MAG robotic welding was investigated.
Ultrasonic welding is a ‘solid-state’ welding process that can be used to join similar or dissimilar materials, by applying high frequency vibration and normal pressure to the weld interface. The major advantage of this method is the low heat input at the weld interface. Because of the cold welding technique, ultrasonic welding can be used to join thin foils to thick sheets and the properties related to the heat at the weld interface are less significant. So welds such as aluminium to copper, aluminium to steel, etc. can be made.
Acoustic emission monitoring is an important technique for surveillance of industrial processes, especially for defining the process parameters or determining whether a machine or structure needs repair. For example, acoustic emission is particularly useful as a means to locate and characterise cracks and other defects in steel bridges.
Global trends force the industry to manufacture lighter, safer, more environmentally friendly, more performant and cheaper products. Combining conventional metals with others or even new materials, offers designers solutions where a design consisting out of one material fails. A multi-material design exploits the material with desired properties for each part of the component or product. Multi-material design is however hindered by challenges in the field of joining technology. The prerequisite for the production of such multi-material components is the availability of suitable joining technologies. New developments for a range of welding processes has however provided the possibility to join dissimilar metals. The project “INNOJOIN” provides insight in new modern welding technologies for welding of dissimilar sheet metals and helped companies to identify the most suitable welding technology for their products.
In the context of the project "SOUNDWELD", the Belgian Welding Institute has invested in an acoustic emission measurement system, which can be used as a non-destructive technique for monitoring the weld quality during welding. In the research project SOUNDWELD, this new non-destructive in-line testing technique is evaluated for different welding processes.