Xiang Cai

Southeast University, China

Title: Investigation of mechanical and corrosion behavior in multi-pass nickel-aluminum bronze and steel composite structures fabricated through wire?arc additive manufacturing

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Biography

Xiang Cai, Ph.D. in Materials Science and Engineering, currently studying at Southeast University, Nanjing, Jiangsu Province, China. He received undergraduate and master's degrees from Jiangsu University of Science and Technology in Zhenjiang, Jiangsu Province, China. Currently, he is engaged in the study of corrosion behavior of 3D printed copper alloys in service under marine environment. Up to now, he have been involved in publishing 11 SCI papers in the field of metallic materials.

Abstract

To replace the traditional cast nickel-aluminum bronze (NAB) parts, this work prepared a NAB/steel composite structure with 316L stainless steel as the inner core using wire-arc additive manufacturing technology. When preparing large-size parts for multi-pass printing, some overlaps between adjacent passes were required to avoid spacing between passes. For the alloy layer printed in the previous pass, the adjacent overlapping area became the heat affected zone. In general, the peak temperatures experienced in each region within the heat affected zone vary, as do the organization as well as the properties within the region. In this experiment, SEM, TEM and other characterization methods were used to investigate the differences in microstructure between the overlap and the substrate of the composite structure, and the mechanical properties and corrosion resistance of the overlap location and the substrate part were tested. The results showed that the grain size at the overlap joint was smaller and the precipitated phase was different from the matrix, almost all of which was ?? (NiAl) phase. The overlaps were mechanically anisotropic and had lower strength and plasticity than the substrate, with tensile strengths 121 and 136 MPa lower than the substrate for vertical and horizontal orientations, and 154 MPa lower strength along 45° orientation; plasticity decreased by 1%, 4% and 7%, respectively. By comparing the results of electrochemical tests and the corrosion morphology of the samples immersed in artificial seawater for a long period, the corrosion resistance of the overlap position was higher than that of the substrate.