Wire + Arc Additive Manufacturing (WAAM) can be used to create large free-form components out of specialist materials such as nickel-base superalloys. Inconel (IN) 718 is well suited for the WAAM process due its excellent weldability. However, during deposition, IN718 susceptible micro-segregation, leading undesirable Laves phase formation in interdendritic regions. Further, encourages columnar grain growth and development a strong fibre texture, anisotropy structure. This unfavourable...

The manufacture of structural components made from nickel-based super alloys would benefit the commercial advantages Wire + Arc Additive Manufacturing (WAAM), as it is commonly expensive to process using other conventional techniques. two major challenges WAAM are residual stress and undesired microstructure. Residual causes part distortion build failures, while as-deposited microstructure does not allow common heat-treatment be effective in achieving desired mechanical properties. This...

Nickel Aluminium Bronzes (NAB) are copper-based multi-phase alloys used extensively in marine applications. NAB is vulnerable to seawater corrosion, however the interaction between its corrosion mechanisms and real-world factors including biofouling, weld microstructure residual stress poorly understood. Seawater tests were performed on plasma-welded laboratory environments, demonstrating that retained β' phase Heat Affected Zone (HAZ) experiences Selective Phase Corrosion (SPC), whereas...

The fabrication of large components using a high deposition rate, near-net shape process like Wire + Arc Additive Manufacturing (WAAM) is promising option for many industries, due to the potential reduction in material wastage and shorter lead times comparison conventional methods. Specialist materials nickel-base superalloys, which are typically used temperature corrosive environments, particularly attractive options their raw costs. Although Alloy 718 seems well suited its good...

The mechanisms of post-weld rolling and how it reduces eliminates residual stress distortion are poorly understood. Finite element analysis was applied to two different methods rolling: the weld bead directly with a single roller beside dual flat roller. models showed that both techniques were able induce compressive into region, which increased load. distribution sensitive coefficients friction between workpiece backing bar. High concentrated plastic deformation within centre bead....

Steel components in advanced gas-cooled reactors (AGRs) are subject to multiaxial deformation at high temperatures. Neutron diffraction has been used study the {111}, {200}, {220} and {311} grain family, also known as lattice plane, response during in-situ loading relaxation of notched bars 316H stainless steel 550 ºC. These experimental conditions have modelled using a multiscale approach that employs finite element models continuum, component, scale boundary for crystal plasticity model....

Residual stresses in materials affect their resistance to the initiation of fracture and subsequent crack growth. Using full-field strain measurements finite element analysis we demonstrate that effect residual stress on a material's growth curve can be understood using elastic-plastic mechanics. It is shown Lei's modified J-integral formulation (Jmod) good predictor load vs extension behaviour an material containing stresses.

Smooth semi-ellipsoids are typically used to simulate the effect of corrosion pits on stress, however, this does not account for pit geometry. Three were identified Nickel Aluminium Bronze samples. These scanned and converted finite element models. The linear elastic stress concentration factor (Kt) FE models was 1.32–1.65 times larger than an equivalent smooth semi-ellipsoid. This suggests that detailed consideration geometry is needed calculate accurate values Kt assumption a...

Updated understanding on the effect of biofouling corrosion rate is needed to protect marine structures as climate change altering seawater physiochemistry and organism distribution. Multi-disciplinary techniques can improve development associated rates metals immersed in natural (NSW). In this study, welded Nickel Aluminium Bronze (NAB) was investigated through long-term immersion tests NSW, simulated (SSW) air. Biofouling affected by geographic location within marina influenced extent. The...

Self-equilibrating residual stresses may occur in materials the absence of external loading due to internal strain inhomogeneity. While favourable distributions stress can bestow an object with appearance superior material properties, most welding processes leave behind particularly unfavourable patterns, causing a greater susceptibility fracture based failure mechanisms and unintended deformation. Currently, heat treatment is primary means removing these stresses, but since formation...

The formation of large residual stresses continues to be a problematic side effect all common welding processes. In this work, localised high pressure rolling gas metal arc welds relieve these has been investigated using strain gauging and neutron diffraction. Rolling was found remove undesirable tensile even induce compressive ones, though only when applied after rather than during welding. Strain measurements taken combined operations show that is because material at the weld line yield as...

AISI Type 304L austenitic stainless steels are extensively used in industries, and welding is an indispensable tool for joining these materials. In a multi-pass weld, the development of residual stress to large extent depends on response weld metal, heat affected zone parent material complex thermo-mechanical cycles during welding. Earlier researchers this area either mechanical tensioning or treatment modify distribution around weld. research, microstructural refinement with modification...

Procedures for structural integrity assessment normally contain criteria to predict the significance of interaction between neighbouring defects in a structure. Here, elastic coplanar semi-elliptical surface cracks is examined detail by considering large number dissimilar crack pairs with different depths and aspect ratios. Surface defect from several procedures are critically assessed found be satisfactory loaded uniform tension. The criterion used R6 Rev. 4 BS 7910:2013 least inherently...

Detrimental residual stresses that occur in welded joints can be removed by rolling the weld seam. In this study we show could applied to much thicker-section welds than has previously been attempted. A stress field introduced localised of an aluminium alloy specimen was studied establish whether plastic deformation caused would sufficient treat thick-section welds. It modelled using finite element analysis and characterised detailed neutron diffraction measurements. During rolling, occurs...

Octet-truss lattice structures can be used for lightweight structural applications due to their high strength-to-density ratio. In this research, octet-truss specimens were fabricated by stereolithography additive manufacturing with a photopolymer resin. The mechanical properties of structure have been examined in three orthogonal orientations under the compressive load. Detailed comparison and description carried out on deformation mechanisms failure modes different orientations. Finite...

Octet-truss lattices printed by photopolymer have been used in this research to investigate the orientation effects on fracture behaviours. were into CT samples three orthogonal orientations. The resistances and crack paths for different orientations obtained compared. finite element method with beam was present study simulate response of structure. Both load reaction simulations compared experimental results. numerical results agree well test