Effect of B and Si on Microstructure and Corrosion Resistance of 316L Stainless Steel Brazed Joints

Abstract

The corrosion behavior of 316L stainless steel joints brazed with three commercial nickel-based filler metals (Ni-7Cr-2.8B-4.5Si, Ni-14.3Cr-3.5B, and Ni-18.5Cr-9.8Si) was comparatively investigated. The B-containing joints form dispersed CrB-type borides, while the Si-only joint develops continuous band-like Ni3Si intermetallics along the seam center. Electrochemical measurements show that the Ni-Cr-B joint exhibits the highest polarization resistance, whereas the Ni-Cr-Si joint shows the most compact passive film. However, cross-sectional corrosion morphology reveals that the Ni-Cr-Si joint suffers the deepest localized attack due to the continuous Ni3Si phase acting as preferential corrosion channels. In contrast, the Ni-Cr-B joint exhibits shallow and uniform corrosion with minimal strength degradation (0.45% loss), while the Ni-Cr-B-Si joint shows the most severe reduction (47% loss) due to preferential attack along boride boundaries, which is facilitated by pre-existing solidification pores in the non-isothermal solidification zone. These findings demonstrate that corrosion resistance is governed by the distribution and continuity of second phases, providing guidance for filler metal selection in corrosive environments.

The authors' abstract, as published at the source. Coatings, 2026 · DOI ↗