Microstructure and Electrochemical Corrosion Behavior of Fe-Cr System Alloys as Substitutes for Ni-Based Brazing Filler Metal
来源期刊：Acta Metallurgica Sinica2016年第8期
论文作者：Kangdao Shi Takahiro Tsunoda Ikuo Shohji
文章页码：697 - 706
摘 要：Two new Fe-Cr system alloys,Fe-20Cr-43Ni-10P（mass%）and Fe-20Cr-20Ni-8P-5Si-2Mo（mass%）,have been developed as substitutes for the expensive Ni-based brazing filler metal used in brazing exhaust gas recirculation coolers.The microstructures and melting properties of the alloys were analyzed by electron probe X-ray microanalyzer and differential scanning calorimetry.The electrochemical characteristics of the alloys were investigated by potentiodynamic polarization testing in an electrolyte solution made in accordance with the standards of the Automobile Manufacturers Association of Germany.Furthermore,the corrosion behaviors of the alloys were investigated by constant-potential polarization testing and surface characterization.It is found that both alloys are composed of solid-solution phases and phosphide phases.The solid-solution phases serve as the anode,and the phosphide phases serve as the cathode in the corrosion reaction for both alloys.Fe-20Cr-43Ni-10 P exhibits galvanic corrosion on the entire surface.In contrast,Fe-20Cr-20Ni-8P-5Si-2Mo is attacked at a few localized areas so that the cavities form on the surface.The corrosion potential(Ecorr) is lower than that of Ni-29Cr-6P-4Si（mass%）for both alloys.This means that the Fe-Cr system alloys are more easily corroded than Ni-29Cr-6P-4Si.The corrosion rate and corrosion resistance cannot be investigated by the corrosion current density(icorr) and polarization resistance（Rp）,respectively,because of localized corrosion of the two alloys.
Kangdao Shi1，Takahiro Tsunoda2，Ikuo Shohji2
1. Graduate School of Engineering,Gunma University2. Graduate School of Science and Technology,Gunma University
摘 要：Two new Fe-Cr system alloys,Fe-20Cr-43Ni-10P（mass%）and Fe-20Cr-20Ni-8P-5Si-2Mo（mass%）,have been developed as substitutes for the expensive Ni-based brazing filler metal used in brazing exhaust gas recirculation coolers.The microstructures and melting properties of the alloys were analyzed by electron probe X-ray microanalyzer and differential scanning calorimetry.The electrochemical characteristics of the alloys were investigated by potentiodynamic polarization testing in an electrolyte solution made in accordance with the standards of the Automobile Manufacturers Association of Germany.Furthermore,the corrosion behaviors of the alloys were investigated by constant-potential polarization testing and surface characterization.It is found that both alloys are composed of solid-solution phases and phosphide phases.The solid-solution phases serve as the anode,and the phosphide phases serve as the cathode in the corrosion reaction for both alloys.Fe-20Cr-43Ni-10 P exhibits galvanic corrosion on the entire surface.In contrast,Fe-20Cr-20Ni-8P-5Si-2Mo is attacked at a few localized areas so that the cavities form on the surface.The corrosion potential(Ecorr) is lower than that of Ni-29Cr-6P-4Si（mass%）for both alloys.This means that the Fe-Cr system alloys are more easily corroded than Ni-29Cr-6P-4Si.The corrosion rate and corrosion resistance cannot be investigated by the corrosion current density(icorr) and polarization resistance（Rp）,respectively,because of localized corrosion of the two alloys.
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