Interfacial Characteristics and Mechanical Properties of 316L and S214 Bimetals Fabricated by Wire-Arc Additive Manufacturing

Cold metal transition wire-arc deposition of S214 bronze/316 L stainless steel bimetals is investigated, and the effects of heat input and deposited sequence on the interfacial behavior of bimetallic structure are systematically characterized. It is demonstrated that 316 L and S214 bimetals are defect-free, with no penetrating cracks or porosity, and that satisfactory metallurgical bonding at the interface is obtained. The interface thickness with low heat input is greater than that with high heat input, and the microstructure of the interface has a honeycomb pattern. The interfacial zone presents the highest microhardness due to the formation of Fe-based solid solutions with high copper content and intermetallic compounds such as AlCrFe2 and AlNi3. As increasing heat input, microstructure of S214 deposited layer in the S214/316 L transforms from alpha-Cu+gamma + Fe-rich phase to alpha-Cu + Fe-rich phase + K phase, and 316 L deposited layer changes from lath ferrite to skeletal ferrite with the determinations of copper and cooling rate. The tensile strength of S214/316 L specimen is substantially higher than that of 316 L/S214. Both 316L and S214 are free of cracking and pitting and have honeycomb joints. At greater heat input, the S214 layer in S214/316L shifts from alpha-Cu + gamma + Fe-rich phase to alpha-Cu + Fe-rich phase + K phase, while 316L layer shifts from lattice ferrite to skeletal ferrite based on copper and cooling rate measurements. The S214/316L sample shows significantly higher tensile strength than 316L/S214.image (c) 2023 WILEY-VCH GmbH