Effect of Electromagnetic Stirring Frequency on Inconel625-High Strength Low Alloy Steel Functionally Graded Material Fabricated by Wire Arc Additive Manufacturing

The influences of electromagnetic stirring (EMS) at different frequencies on the formability, microstructure, mechanical properties and corrosion behavior of Inconel625-HSLA (high-strength low-alloy) steel functionally graded materials (FGMs) were studied. A wire arc additive manufacturing (WAAM) system with EMS at different frequencies was applied to fabricate the Inconel625-HSLA steel FGMs. The ratio of the maximum effective area (R-max) was used to illustrate the formability of the FGMs. The R-max of the FGMs was increased from 54.7 to 84.8% after EMS at a frequency of 4 Hz with an excitation current of 2 A. The tensile strength and microhardness were tested, and electrochemical tests were conducted to study the corrosion resistance of the FGMs. Compared to the FGM without EMS, the FGM fabricated in EMS at a frequency of 4 Hz and excitation current of 2 A had a primary dendrite spacing that was an average of 13.7% lower, an increased average tensile strength and microhardness (12.5 and 6.7%, respectively), and an increased the corrosion potential (E-corr), pitting potential (E-p) and passive region (Delta E); these values increased from - 186 to - 139 mV(SCE), from 299 to 477 mV(SCE) and from 113 to 338 mV(SCE), respectively.