Manufacturing conditions of bimetallic samples based on iron and copper alloys by wire-feed electron beam additive manufacturing

Introduction. Wire-feed electron beam additive manufacturing (EBAM) is a promising production technology, offering unprecedented control over interface design in composite materials, which is challenging to achieve using conventional methods. The ability to control localized metallurgical processes within the melt pool is a key advantage of EBAM technology. This study investigates the influence of key EBAM parameters (wire feed configuration, scanning strategies, and linear energy input) on achieving diverse interface designs in bimetallic samples composed of copper and iron-based alloys. Establishing the relationship between microstructure evolution and 3D printing parameters is of great importance for the development of EBAM. The purpose of this study is to elucidate the effects of fundamental EBAM process parameters (beam current, wire feed rate, heat input, scanning strategy, and intrinsic material properties) on the fabrication of high-quality copper-iron bimetallic samples exhibiting both sharp and smooth interfaces, as well as heterogeneous material distributions. Research Methods. This study heavily emphasizes experimental investigations to optimize the EBAM process. Bimetallic samples featuring sharp interfaces, smooth interfaces, and heterogeneous microstructures, based on copper and iron alloys, were fabricated using wire-feed EBAM. The study analyzed the values of heat input depending on the layer being deposited; the wire feed rate depending on the material used, and the types of printing strategies depending on the ratio of dissimilar materials in bimetallic samples. A Pentax K-3 digital camera, equipped with a 100 mm focal length lens, was employed for high-resolution visual inspection and quality assessment of the fabricated bimetallic samples with varying interface designs. Results and discussion. Based on an in-depth understanding of the factors governing electron beam-material interactions, this work systematically details the potential for creating components with controlled sharp or smooth interfaces, as well as heterogeneous material architectures. Furthermore, the study briefly outlines process control methodologies aimed at minimizing defects, considering factors influencing melt pool dynamics, including the precise regulation of thermal conditions during 3D printing process. A fixed heat input was prescribed for each material to achieve a sharp interface morphology: specifically, 0.09 kJ/mm for the deposition of M1 copper layers, which is 2.5 times lower than the heat input used for depositing Cu-9 Al-2 Mn copper alloy layers. Similarly, a heat input of 0.17 kJ/mm was used for 0.12 C-18 Cr-9 Ni-Ti stainless steel layers, which is 1.5 times lower than that for 0.09 C-2 Mn-Si steel alloy layers. In contrast, the fabrication of smooth interfaces relied on dynamically adjusting the heat input and wire feed rates as a function of the layer being deposited and the target composition. The formation of heterogeneous structures required the use of tailored scanning strategies during EBAM, depending on the volume fraction of dissimilar alloys deposited via the wire feedstock. The successful fabrication of defect-free copper-iron bimetallic samples was achieved through careful control of the EBAM process.

Additive manufacturing, wire-feed electron beam additive manufacturing (EBAM), sharp interface, smooth interface, heterogeneous structure, heat input, Macrostructure