Residual stress and microstructure properties by trailing cooling of argon gas of wire and arc additive manufacturing

To reduce the large residual stress and refine the coarse grains of the deposited layers caused by excessive heat input in the wire and arc additive manufacturing (WAAM), a trailing cooling of argon gas-based WAAM method was proposed. A finite element model of stress field in WAAM with and without cooling source is established. The influence of the cooled gas on the stress and deformation of the additively manufactured parts is analyzed in detail. The results show that, compared with additive manufacturing without cold source, the application of cold source can effectively reduce the longitudinal stress level in the deposited layer area and improve the dimensional accuracy of the deposited layers under the condition of cold source additive manufacturing, the maximum joint displacement is reduced by 24%. Analysis of the microstructure and properties of the deposited layers shows that the cooled trailing gas can refine the grain size of the deposited metal and improve the tensile strength and elongation of the deposited metal, which may be increased by 10% and 8%, respectively.