Mechanical properties of carbon steel by compound arc and vibration shock forging-rolling

To solve problems of coarse grains and low mechanical performance in low carbon steel parts fabricated by wire and arc additive manufacturing (WAAM), a novel compound arc and vibration shock forging-rolling (CAVSFR) method was proposed in this study. Carbon steel components were fabricated by the proposed method. And results showed that the total deformation of 28.3 % was obtained and the average grain size was reduced from 9.6 mu m of WAAM to 6.4 mu m. Grain refining was attributed to the static-force rolling, vibration-shock forging and micro self-forging of the molten pool. The large deformation in the medium-high-temperature zone, which provided more nucleation sites, accounted for grain refining in both static-force rolling and vibration-shock forging. Vibration shock greatly promoted dendrite fragmentation and more dendrite fragments were obtained as nuclei for new grains. Besides, the larger constitutional supercooling helped these nuclei survive and induced more nucleation, which could refine grains. These two factors were responsible for the grain refining in micro self-forging of the molten pool. What's more, the refined grains enhanced the strength and plasticity of the material. The ultimate tensile strength (UTS), yield strength (YS) and elongation of the optimized component manufactured using the proposed method were increased to 555 MPa, 391 MPa and 38.9 %, which were enhanced by 14.2 %, 8.6 % and 1.8 % respectively and exceeded that of the wrought low alloy steel with the UTS of 550 MPa. Compared with other methods, small load and simple equipment could obtain components with the high performance through the proposed method.