WAAM Technique: Process Parameters Affecting the Mechanical Properties and Microstructures of Low-Carbon Steel

Abstract

This study surveys the influences of travel speed, voltage, and intensity on the characteristics of low-carbon steel samples generated by the Wire Arc Additive Manufacturing (WAAM) technique. The results indicated that the WAAM samples have isotropy grain shape, with grain size number values varying from about 8 to 12. Interestingly, the WAAM sample achieves better mechanical properties with a higher ultimate tensile strength (UTS) value and higher elongation at break value than the original wire. The UTS value of the WAAM sample is 21–40% higher than the original steel wire. The WAAM sample with a travel rate of 350 mm·min−1, a voltage of 24 V, and an electrical intensity of 120 A reaches the highest UTS value of 694 MPa. The WAAM sample with a travel rate of 400 mm·min−1, a voltage of 22 V, and an electrical intensity of 170 A gains the lowest UTS value of 599 MPa. Moreover, the elongation values oscillate around 41–57%, two or three times higher than the original steel wire. SEM microstructure reveals a ductile fracture surface with dimples of the samples after the tensile test, indicating the toughness of the samples. The fracture surface also shows the equiaxial shape and grain size of the WAAM samples. According to Taguchi analyses, the travel rate factor greatly impacts grain size. The voltage factor has the highest effect on the UTS value. The intensity factor has the most significant impact on the elongation value.