Wire arc additive manufacturing Al-5.0 Mg alloy: Microstructures and phase composition

Wire arc additive manufacture is well applied in the fabrication of Al-5.0 Mg products. The investigation of microstructure morphology and phase composition in different regions is not enough. Therefore, the factors of microstructure morphology, dislocations densities and phase composition are worthy to study. Investigations of microstructure morphology demonstrated that the cross-section along the deposition direction has diversified grain size and the diversity increases the dislocation density and decreases the residual stress. The preferred orientation of grain growth analyzed by XRD explained that the decreasing intensity of (200) could improve the homogeneity. EDS results revealed that Al and Al 3 Mg 2 were the main phases. TEM results demonstrated that there was Al 2 Mg formed inside grains and the irregular shapes of precipitations. The temperature gradient in the two regions is the main factor causing the differences in dislocation density, precipitations formation and microstructure diversity • Diversity in preferred orientation and microstructure is affected by the temperature gradient in different regions. • Al and Al 3 Mg 2 are the main phases and the Al 2 Mg is detected. • High dislocation density resulting from uneven microstructure could reduce the residual stress.