As a rapidly evolving advanced digital manufacturing technology, additive manufacturing (AM) has its advantages including short manufacturing cycle, material saving, and complexity for free. It has great potential for application in marine and offshore engineering. However, stress corrosion damage will be a big threat for the additively manufactured metal parts in the ocean environment due to large residual stresses generated in the building process. This paper focuses on the effect of ultrasonic peening treatment (UPT) on stress corrosion resistance of AlSi10Mg components fabricated using Selective Laser Melting (SLM). Firstly, AlSi10Mg specimens were prepared using an SLM machine, and UPT was conducted on the specimen’s top surface. Then, a series of measurements and analyses were carried out for the specimens before and after the UPT process. The residual stresses and hardness of the specimens were measured, and the surface morphology was observed using a scanning electron microscope (SEM). The resistance of stress corrosion was evaluated by the electrochemical corrosion test. The experimental results show that UPT can significantly improve stress corrosion resistance of SLM-fabricated specimens.

Wire and arc additive manufacturing (WAAM) is a novel technique for fabricating large and complex components applied in the manufacturing industry. In this study, a low-carbon high-strength steel component deposited by WAAM for use in ship building was obtained. Its microstructure and mechanical properties as well as fracture mechanisms were investigated. The results showed that the microstructure consisted of an equiaxed zone, columnar zone, and inter-layer zone, while the phases formed in different parts of the deposited component were different due to various thermal cycles and cooling rates. The microhardness of the bottom and top varied from 290 HV to 260 HV, caused by temperature gradients and an inhomogeneous microstructure. Additionally, the tensile properties in transversal and longitudinal orientations show anisotropy characteristics, which was further investigated using a digital image correlation (DIC) method. This experimental fact indicated that the longitudinal tensile property has an inferior performance and tends to cause stress concentrations in the inter-layer areas due to the inclusion of more inter-layer zones. Furthermore, electron backscattered diffraction (EBSD) was applied to analyze the difference in Taylor factor between the inter-layer area and deposited area. The standard deviation of the Taylor factor in the inter-layer area was determined to be 0.907, which was larger than that in the deposited area (0.865), indicating nonuniform deformation and local stress concentration occurred in inter-layer area. Finally, as observed from the fracture morphology on the fractured surface of the sample, anisotropy was also approved by the comparison of the transversal and longitudinal tensile specimens.

A bulk specimen and two different lattice sandwich structures composed of 316L stainless steel were fabricated via selective laser melting. This study analysed the acoustic properties, including sound insulation and sound absorption, of the three kinds of structures, which were produced via selective laser melting under the same process parameters. The results showed that the difference in the unit structures, rather than microstructural difference, was the main reason for the difference in acoustic properties between the samples. Under the same process parameters, the microstructure of the different structures had the same cell structure. However, the sound absorption properties of the lattice sandwich structures were better than those of the bulk sample in the measured frequency range of 1–6.3 kHz. The lattice sandwich structure with 2.5 × 2.5 × 2.5 mm³ unit structures exhibited excellent sound insulation properties in the frequency range of 1–5 kHz.