Microstructure and Corrosion Resistance of Arc Additive Manufactured 316L Stainless Steel

Abstract

The gas tungsten arc welding based additive manufacturing (GTAW-AM) was carried out by printing 316L austenitic stainless steel on carbon steel substrate with different arc currents (140, 160, 180 A). Microstructure and corrosion resistance of additive manufactured components were investigated. The results show that the microstructure of the GTAW-AM austenitic stainless steel is obviously changed by the arc current. With arc current increasing from 140 to 180 A, the austenite grains become coarse due to the effect of welding heat input. Meanwhile, the quantity of ferrites in the austenite matrix is decreased and the morphology transforms from lath to skeleton. Moreover, a phases are finally formed under the arc currents of 180 A owing to high welding heat input. Therefore, as the microstructure transform into coarse-grained austenites, low-quantity ferrites and new-generated a phases, the GTAW-AM austenitic stainless steel presents a significantly decrease in corrosion resistance. And the reduction of corrosion resistance is mainly due to the formation of a phase as a result from consuming the large amounts of Cr element from the matrix.

Keywords

austenitic stainless steel / additive manufacturing / microstructure / corrosion resistance

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