Characterization of welding and metal additive manufacturing processes

E. Bertrand, L.Couturier, P. Paillard, P. Dahéron

Welding is a relatively complex process of materials shaping. Indeed, it is a so-called multiphysical process. It calls on knowledge in physics, fluid mechanics, chemistry, metallurgy and mechanics.
The same goes for the metal additive manufacturing processes that we are studying within our team.
It is therefore important to quantify the various parameters related to welding and metal additive manufacturing operations:

• The electrical welding parameters: welding current and voltage (PicoScope oscilloscope);
• Observation of the molten bath, of the electric arc, of the detachment of the droplets of filler metal (KEYENCE very high speed camera);
• Recording of thermal fields (FLIR Orion Multispectral Infra Red camera);
• Fine temperature measurements by thermocouple.

Keywords : Electrical measurements, thermal measurements, high speed visualization

 

We have developed coupled instrumentation means that allows us to synchronize a number of characterizations of welding and metal additive manufacturing processes (Figure 1).

Figure 1 : instrumented welding bench

 

The data collected by the different characterization systems allow us to highlight the influence of welding processes and welding parameters on the behavior of the welding electric arc (Figure 2a), on the deposit of the metal and on movements in the molten bath (Figure 2b). It also allows us to see the influence of welding processes on thermal fields in welded assemblies (Figure 3). Finally, it is possible for us to study the influence of the welding parameters and of the resulting thermal field on the working properties (mainly mechanical properties) in relation to the obtained microstructures (Figure 4). These infrared camera measurements are often coupled with more traditional thermocouple measurements (Figure 4).

Within our team, we mainly work on arc welding processes (TIG, MIG, MAG), which are also our additive manufacturing processes, and resistance welding processes. As part of collaborations, we study other welding processes such as rotary or linear friction welding, friction stir welding, Laser welding and hybrid Laser welding. Finally, the very varied experimental data that we collect allow us to validate numerical welding simulations (SNS).

a	b
Figure 2 : synchronization of the electrical parameters of high-speed imaging, a) influences of electrical parameters on the arc, b) influence of electrical parameters on the detachment of filler metal’s droplets.
	c
Figure 3 : influence of the welding parameters and welding processes on the thermal fields in the parts to be assembled: a) IR thermography of the MIG CMT® Pulsed process, b) IR thermography of the MIG CMT® process and c) temperature gradient as a function of the processes welding.
Figure 4 : thermocouple measurements of thermal fields during a WAAM additive manufacturing operation.

 

Collaborations

Institut de Recherche Dupuy de Lomes (IRDL)