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Aluminum alloys are widely used in automotive construction, and since the introduction of biogenic ethanol into fuels, the issue of nonaqueous alcoholate corrosion has become an important topic. In this paper, the kinetics of AA1050 temperature‐induced alcoholate pitting corrosion are examined experimentally with a specially constructed microreactor. The generated data are utilized to create a phase field model for the pit growth phase. The effects of ethanol‐blend composition and water content are quantitatively assessed and simulated. Phase field simulations allow for the first time the mechanistic characterization of the chemical corrosion process with a water content of up to 0.3% and an estimation of relevant reaction parameters at temperatures of up to 150°C. The approach can further be utilized to develop strategies for minimizing corrosion risk in‐service. [ABSTRACT FROM AUTHOR]

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Hot-dip galvanized steel structures are well-established and state of the art for public and industrial buildings. They can achieve a corrosion protection period in the magnitude of the lifetime of the structures (≥100 years). The application of this corrosion protection system would also have great potential in bridge construction. Economic efficiency and sustainability in bridge construction are, in addition to the cost of new building, determined by the incurred maintenance costs. A prior research project had demonstrated hardly any losses on the fatigue strength compared with the nongalvanized steel components. Large bridge structures must be designed with assembly joints. Welded field joints of hot-dip galvanized components require a complex pretreatment and posttreatment of the corrosion protection. Nevertheless, onsite applied corrosion protection cannot reach the protection durability of a hot-dip galvanizing. This technological restriction can be avoided by the use of hot-dip galvanized bolted connections. Slip-resistant pretensioned connections with pretensioned bolts have been proven successful in steel bridge construction. Major scientific investigations are not yet available for the use of slip-resistant connections for hot-dip galvanized joints. Technical and scientific foundations for the application of hot-dip galvanized bolted connections in cyclically loaded steel and composite bridge constructions, based on the European standard for steel constructions are investigated within the scope of this research project. Construction and design recommendations are provided. [ABSTRACT FROM AUTHOR]

The microstructural anisotropy caused by the highly oriented solidification of the metal Laser Powder Bed Fusion (PBF-LB/M) process affects mechanical short- and long-term properties. Component build orientation influences grain morphology and orientation, and thus, mechanical properties. While the creep behaviour of samples manufactured parallel and perpendicular to the build direction are studied intensively, the 45° build orientation remains uncharacterised. In this study, IN738LC creep samples are manufactured via PBF-LB/M in three build orientations (0°, 45° and 90°). While the results of 90° and 0° are as expected, where 90° achieves the longest time to rupture and largest rupture strain, the 45° specimen shows the least fracture time. Differences in microstructure and twinning behaviour are identified as one of the root causes for this unexpected behaviour. This study discusses the correlation between microstructure, twinning and build orientation and their effect on creep behaviour, with special focus on the 45° build orientation. [ABSTRACT FROM AUTHOR]

Precise determination of the remaining service life of technical components requires sufficient knowledge of fatigue crack growth behaviour and the growth rate of defects. Cracks in real components often experience multiaxial far field stresses due to their complex geometry and composite loadings acting on it. Digital image correlation (DIC) is well established for crack length and displacement measurements, but it usually requires sample preparation with speckle paint and interferes with mechanical extensometers. To overcome these limitations, we use a novel 2D DIC system combining a graphics processing unit (GPU) with a CoaXPress 2.0 camera, acquiring up to 3 GB/s of image data. It enables real‐time evaluation of both integral strain like an extensometer and full‐field DIC on images selected automatically in real‐time. This combination enables the use of one single sensor for strain‐controlled testing and fatigue crack growth characterisation. The full‐field displacement is compared to a finite‐element model (FEM) simulating the actual crack contour measured by the DIC system. The results show that high‐performance DIC has the potential to simultaneously simplify crack‐growth experiments and provide comprehensive fracture mechanical information. [ABSTRACT FROM AUTHOR]

In present work, the monotonic and cyclic properties of a novel Al‐Mg‐Zn‐Cu‐Si compositionally complex alloy (CCA) are investigated. Microstructural studies reveal that a eutectic phase and fishbone‐type structures are embedded in the Al‐matrix. The mechanical properties of this CCA obtained under compressive loading are found to be promising. However, low ultimate strength and brittle behavior are seen under tension. The fatigue performance of the alloy in the low‐cycle fatigue (LCF) regime is poor. Microstructural features and fracture surface analysis point to the fact that the presence of brittle intermetallic phases and shrinkage defects are responsible for the poor tensile properties and inferior LCF behavior. Homogenization at 460 and 465 °C for 3 h, 6 h, and 24 h results in spheroidization of all coarse precipitates. However, the heat treatment used is unsuitable to enhance the mechanical properties of this CCA. [ABSTRACT FROM AUTHOR]

Components manufactured with Metal Laser Powder Bed Fusion (PBF-LB/M) are built in a layerwise fashion. The PBF-LB/M build orientation affects grain morphology and orientation. Depending on the build orientation, microstructures from equiaxed to textured grains can develop. In the case of a textured microstructure, a clear anisotropy of the mechanical properties affecting short- and long-term mechanical properties can be observed, which must be considered in the component design. Within the scope of this study, the IN738LC tensile and creep properties of PBF-LB/M samples manufactured in 0° (perpendicular to build direction), 45° and 90° (parallel to build direction) build orientations were investigated. While the hot tensile results (at 850 °C) are as expected, where the tensile properties of the 45° build orientation lay between those of 0° and 90°, the creep results (performed at 850 °C and 200 MPa) of the 45° build orientation show the least time to rupture. This study discusses the microstructural reasoning behind the peculiar creep behavior of 45° oriented IN738LC samples and correlates the results to heat-treated microstructures and the solidification conditions of the PBF-LB/M process itself. [ABSTRACT FROM AUTHOR]

Copyright of Materialwissenschaft und Werkstoffechnik is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Friction stir welding enables joining of high‐strength, lightweight aluminum alloys, e.g., EN‐AW‐7075, below the melting point by induced plastic deformation. Therefore, heat transfer into the adjacent regions beneath the weld seam is significantly reduced as compared to fusion welding processes such as laser beam welding. However, specific zones along the weld seam area are susceptible to localized corrosion due to grain growth and the precipitation of intermetallic phases. Thus, several approaches toward lowering the corrosion susceptibility of the heat‐affected zone are presented. Special interest is given to increasing the plastic deformation by the use of novel multipin welding tools that eventually facilitate reduced heat input during welding as a result of substantially lower tool revolutions. The corrosion behavior is tested by means of full material immersion tests and electrochemical measurements which provide insight into the corrosion kinetics. Using pre‐ and postmortem microstructural analysis, the mechanisms influencing the initiation of corrosion can be identified. Supported by in‐operando temperature measurements, the varied welding parameters and their interrelationships to corrosion resistance can be derived. Furthermore, recommendations on optimal welding parameters to obtain enhanced corrosion resistance can be deduced. [ABSTRACT FROM AUTHOR]