Corrosion behaviour of point‐by‐point wire and arc additively manufactured steel bars

Abstract

Robot‐assisted point‐by‐point wire and arc additive manufacturing is considered a promising technology for optimising the production of metallic connections used in complex nodes, space trusses or grid shells. While mechanical properties of such elements were proved suitable for structural applications, a lack of knowledge exists concerning their durability. We investigate the corrosion performance of low carbon steel bars produced by point‐by‐point wire and arc additive manufacturing. Metallurgical analyses show uniform microstructure along the length of the steel bars. Corrosion initiation tests in simulated atmospheric exposure reveal the influence of geometry on corrosion, in particular, the presence of concave areas. The surface state and postprinting cleaning processes were investigated with microscopy and electrochemical techniques. These experiments indicate a detrimental effect of oxide scales due to the wire and arc additive manufacturing process on the corrosion behaviour of the steel. The results of the study show that special care must be given to the geometry and surface state of wire and arc additively produced low carbon steel components in case of long‐term use.

Automated local electrochemical characterization on metals with complex shape and practice-related surface state

“…It is worth to mention that no ohmic drop compensation method was used during polarization procedures. This was justified on the basis of results presented in a previous contribution [18], where with a test solution similar as the one used in the present experiment, namely 0.01 M NaOH and NaCl and 0.1 M NaOH and NaCl, the apparent tip resistance was found to be around 25 -50 kΩ. This value was 2 -3 order of magnitude lower than the polarization resistance of comparable electrodes being studied.…”

“…Many parameters of the setup can be adjusted and offer the opportunity to use the setup in the future in different domains. As an example, the setup was recently used in the characterization of point-by-point wire and arc additively manufactured steel bars [18]. Fig.…”

Ductility and Buckling Behaviour of Point‐by‐Point Wire Arc Additively Manufactured Steel Bars

“…Detailed results for the bars printed with other angles and tested under tensile loading can be found in [9]. Furthermore, the corrosion behaviour of such bars was investigated in [23]. The results of the WAAM steel bars printed with different angles and tested under compressive loading are being evaluated at the moment of writing this paper and will be presented in a later journal publication.…”

Mechanical and microstructural features of wire-and-arc additively manufactured carbon steel thick plates

“…Recent applications of WAAM for large-scale structures exploited two different deposition strategies: (i) a "continuous" strategy, i.e., layer-by-layer deposition, suitable for planar and shell elements [6][7][8] and (ii) a "dot-by-dot" strategy to realize lattice and diagrid structures, such as the awarded WAAM diagrid column designed by the research group at University of Bologna (see, e.g., [9]). Specific considerations must be made when dealing with WAAM elements: (i) the inherent surface roughness, which could influence the mechanical properties [10][11][12][13][14], (ii) the marked mechanical anisotropy due to the specific microstructure [15][16][17][18][19][20][21], (iii) the influence of process parameters in both geometrical and mechanical response [22][23][24]. Hence, specific knowledge in advanced manufacturing technology should be combined with structural design competences to efficiently fabricate high-performance WAAM elements [25].…”