Tension and Charpy V-Notch Impact Properties of Wire Arc Additively Manufactured ER70S-6

Abstract

Wire arc additively manufactured (WAAM) steels cannot be adopted into civil structures until knowledge of their material behaviors is expanded. American Welding Society (AWS) ER70S-6 is a common welding wire feedstock compatible with ASTM A992 and ASTM A709 Grade 50 steel, grades regularly used in building and bridge construction. The objective of this study was to show that WAAM ER70S-6 can attain suitable tensile and impact properties for structural applications. Two material characterization walls were fabricated using ER70S-6 feedstock at two interpass temperatures. Tension and Charpy V-notch (CVN) impact tests were conducted on specimens from each wall, oriented in several different directions with respect to the build direction (BD) of the wall, to evaluate the degree of anisotropy and the effects of the interpass temperature in WAAM ER70S-6. The results were compared to the requirements of the American Association of State Highway and Transportation Officials (AASHTO) and AWS standards. Substantial anisotropy was not observed in yield and ultimate stress. However, low levels of anisotropy were observed for elongation at fracture of the tension specimens and impact energies of the CVN specimens. Yield and tensile strength generally increased with lower interpass temperature, while elongation typically decreased with lower interpass temperature. The AWS minimum requirements were met by the average yield and tensile stresses of the lower interpass temperature wall, while the higher interpass temperature wall did not meet the AWS minimum requirement. The average elongation at fracture of specimens from both walls exceeded the minimum value required by AWS. The CVN specimens fabricated at the higher interpass temperature generally had higher upper-shelf impact energies. However, all CVN specimens tested surpassed the AASHTO requirements across all temperature zones. These results suggest that WAAM ER70S-6 has promise as a structural material.