Impact of a Dynamically Modulated Process Force and Micro- and Nanoscale Intermediate Layers on the Strength of Diffusion-Bonded Joints

Abstract When developing suitable process technologies for joining materials, the focus is on creating the desired property profile of the joint, ensuring process stability and reproducibility, and achieving cost-effectiveness. In view of these considerations, further developments in diffusion-based joining aim to reduce process times, lower temperatures, and reduce force levels to process the materials with minimal damage and to achieve joint strengths that are comparable to those of conventional processes. The study presents an innovative engineering concept for the application of dynamically modulated process forces. The influence of a pulsating process force and micro- and nanoscale intermediate layers on the joint strength is demonstrated using the example of unalloyed heat-treatable steel C45 (1.0503), as well as austenitic chromium-nickel-molybdenum stainless steel X2CrNiMo17-12-2 (1.4404). The highest tensile strength values were achieved at a joining temperature of 950 °C, a surface pressure of 10 N/mm 2 , and a holding time of 600 seconds, with a percentage value greater than 90% in comparison with the heat-treated base material. The application of a dynamically modulated process force enabled the attainment of tensile strengths exceeding 80% of the base material at a joining temperature reduced to 750 °C, a surface pressure of 30 N/mm 2 , and an identical holding time. This resulted in significantly elevated values compared to those obtained with a statically applied process force.