Ultrasonic additive manufacturing (UAM) and diffusion treatment of Steel-Ni multilayered parts

Ultrasonic additive manufacturing (UAM) is an innovative method for the fabrication of 3D products by adding thin metal strips one on top of the other and applying ultrasonic vibrations, combined with compressive normal force. An adequate solid state joining between the layers may be achieved during UAM for relatively soft materials, such as Cu, Al and Ti. It is very attractive to apply UAM to fabricate laminated steel parts due to their low cost and the possibility to achieve required properties. However, UAM of 316L stainless steel and 4130 steel did not provide a sufficient bond quality. It was suggested to use an interlayer of soft metal (for instance, Ni) to improve bond quality and mechanical properties of UAM parts. UAM multilayer parts of 4130 steel (200µm) with Ni interlayers (50µm) were successfully fabricated. In order to improve mechanical properties of the parts prolonged diffusion thermal treatment was conducted at 1000°C. Inter-diffusion in the Fe-Ni system was analyzed and investigated experimentally. The comparison of the calculated and experimentally obtained concentration profiles will be discussed.