For certain additive manufacturing technologies the choice of available materials is currently limited. The development of process parameters is especially elaborate for powder bed technologies. Currently, there is no common approach concerning the procedure and documentation. This work proposes a methodology for the initial development of process parameters for new L-PBF (laser powder bed fusion) alloys. Key elements are the examination of the laser–powder-bed interaction by single laser track experiments and an iterative design of experiment (DoE) approach for the development of volumetric parameters. Two types of single laser track experiments are presented and provide information regarding the laser track width and depth as well as the resulting surface roughness and melt pool classification. Based on the information gained, suitable process windows for a DoE study can be defined by avoiding parameter settings unsuitable for production or measurement. Gradually, input variables are identified and iterative steps reduce the process window in order to optimize the desired target values. Near-surface exposure parameters are developed by a one-dimensional parameter variation and metallographic investigations. The approach is primarily designed for the initial development of process parameters for new L-PBF alloys. However, the information gained can also be used to optimize established parameter sets regarding new target values (productivity, mechanical properties), optimize process parameters for specific components or for a microstructural design.

Ultrasonic metal welding is an energy-efficient, fast and clean joining technology without the need of additional filler materials. Single spot ultrasonic metal welding of aluminum to steel sheets using automotive materials has already been investigated. Up to now, further studies to close the gap to application-relevant multi-metal structures with multiple weld spots generated are still missed. In this work, two different spot arrangements are presented, each consisting of two weld spots, joined 0.9 mm thick sheets of wrought aluminum alloy AA6005A-T4 with 1 mm sheets of galvannealed (galvanized and annealed) dual-phase steel HCT980X. An anvil equipped with variable additional clamping punches was used for the first time. The tensile shear forces reached 4076 ± 277 N for parallel connection and 3888 ± 308 N for series connection. Temperature measurements by thermocouples at the interface and through thermal imaging presented peak temperatures above 400 °C at the multi-metal interface. Microscopic investigations of fractured surfaces identified the Zn layer of the steel sheets as the strength-limiting factor. Energy-dispersive X-ray spectroscopy (EDX) indicated intermetallic phases of Fe and Zn in the border areas of the weld spots as well as the separation of the zinc layer from the steel within these areas.

Ultrasonic metal welding (USMW) is widely used in assembling lithium-ion (Li-ion) battery packs due to its advantages in joining dissimilar and conductive materials in the solid state. However, the welding process and mechanisms are not yet clearly understood. In this study, dissimilar joints of aluminum alloy EN AW 1050 to copper alloy EN CW 008A were welded by USMW to simulate the tab-to-bus bar interconnects for Li-ion battery assembly. Qualitative and quantitative investigations were carried out on plastic deformation, microstructural evolution, and the correlated mechanical properties. During USMW, the plastic deformation concentrated on the Al side. The thickness of Al was reduced by more than 30%; complex dynamic recrystallization and grain growth occurred near the weld interface. The mechanical performance of the Al/Cu joint was evaluated with the tensile shear test. The failure load gradually increased until a welding duration of 400 ms, and then remained almost constant. The obtained results showed that the mechanical properties were greatly influenced by plastic deformation and microstructure evolution, which provides guidance for improving the weld quality and the process in general.

The thermoplastic polymer polyether ether ketone (PEEK) offers thermal and mechanical properties comparable to thermosetting polymers, while also being thermally re-processable and recyclable as well as compatible with fused filament fabrication (FFF). In this study, the feasibility of joining additively manufactured PEEK in pure and short carbon-fiber-reinforced form (CF-PEEK) is investigated. Coupon-level samples for both materials were fabricated using FFF with tailored integrated welding surfaces in the form of two different energy director (ED) shapes and joined through ultrasonic polymer welding. Using an energy-driven joining process, the two materials were systematically investigated with different welding parameters, such as welding force, oscillation amplitude and welding power, against the resulting weld quality. The strengths of the welded bonds were characterized using lap-shear tests and benchmarked against the monotonic properties of single 3D-printed samples, yielding ultimate lap-shear forces of $2.17$$\mathrm{k}$$\mathrm{N}$ and $1.97$$\mathrm{k}$$\mathrm{N}$ and tensile strengths of $3.24$$\mathrm{M}$$\mathrm{Pa}$ and $3.79$$\mathrm{M}$$\mathrm{Pa}$ for PEEK and CF-PEEK, respectively. The weld surfaces were microscopically imaged to characterize the failure behaviors of joints welded using different welding parameters. Samples welded with optimized welding parameters exhibited failures outside the welded region, indicating a higher weld-strength compared to that of the bulk. This study lays the foundation for using ultrasonic welding as a glue-free method to join 3D-printed high-performance thermoplastics to manufacture large load-bearing, as well as non-load-bearing, structures, while minimizing the time and cost limitations of FFF as a fabrication process.