Study on corrosion fatigue behavior and mechanism of 6005A aluminum alloy and welded joint

Purpose The purpose of this paper is to determine the corrosion fatigue behavior and mechanism of 6005A aluminum alloy and welded joint. Design/methodology/approach Electron back-scattered diffraction (EBSD) were adopted to characterize the microstructure of 6005A aluminum alloy and welded joint. Through potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and corrosion fatigue experiments, the corrosion fatigue behavior and mechanism of 6005A aluminum alloy base metal and welded joint were studied. Findings The results show that the corrosion fatigue crack initiation of 6005A aluminum alloy base metal and welded joint is mainly caused by the preferential anodic dissolution and hydrogen concentration in the areas with inclusions and welding defects. Originality/value The research is an originality study on the corrosion fatigue behavior and mechanism of 6005A aluminum alloy and welded joint.

A Test on the Potential of a Low Cost Unmanned Aerial Vehicle RTK/PPK Solution for Precision Positioning

This paper investigated the achievable accuracy from a low-cost RTK (Real Time Kinematic)/PPK (Post Processing Kinematic) GNSS (Global Navigation Satellite Systems) system installed on board a UAV (Unmanned Aerial Vehicle), employing three different types of GNSS Bases (Alloy, RS2 and RING) working in PPK mode. To evaluate the quality of the results, a set of seven GCPs (Ground Control Points) measured by means of the NRTK (Network Real Time Kinematic) technique was used. The outcomes show a RMSE (Root Mean Square Error) of 0.0189 m for an ALLOY Base, 0.0194 m for an RS2 Base and 0.0511 m for RING Base, respectively, on the vertical value of DEMs (Digital Elevation Models) obtained by a photogrammetric process. This indicates that, when changing the Base for the PPK, the solutions are different, but they can still be considered adequate for precision positioning with UAVs, especially when GCPs could be used with some difficulty. Therefore, the integration of a RTK/PPK GNSS module on a UAV allows the reconstruction of a highly detailed and precise DEM without using GCPs and provides the possibility to carry out surveys in inaccessible areas.

The Effect of Dissolved Nitrogen on the Fatigue Behavior of Ti-6Al-4V

The effect of nitrogen additions on fatigue behavior has been examined in near-equiaxed, rolled Ti-6Al-4V bar. This is the first-time nitrogen content that has been systematically explored with respect to monotonic and cyclic properties in a Ti-6Al-4V alloy base composition. Nitrogen additions were found to increase the $$\beta $$ β -transus temperature and strength, but they decreased ductility, even in microstructures where some $$\beta $$ β phase remained. This carried across into both the low- and high cycle fatigue behavior; even small contents of 240 and 560 ppmwN caused reductions in both low cycle fatigue life and high cycle fatigue strength. In samples containing 240 and 560 ppmwN, a conventional striated fractographic appearance was observed, but a dramatic change to a macroscopically brittle fracture surface was observed at 1800 and 3600 ppmwN, but still with substantial evidence of plasticity at the microscale. Therefore, neither microstructure or fractographic examination, nor EDX-based compositional analysis in the electron microscope are necessarily a reliable indicator of an absence of deleterious nitrogen contamination. This is significant for the investigation of potentially nitrogen-contaminated surface-initiated cracks, either due to service or processing exposures.

Studies on structural, mechanical and erosive wear properties of ZA-27 alloy-based micro-nanocomposites

Metal matrix nanocomposites represent a relatively new class of material, which is still being extensively investigated. Most of the studies, however, are devoted to aluminium- or magnesium-based nanocomposites. A limited number of studies focus on zinc alloy base nanocomposites, with fewer still concentrating on zinc alloy base micro-nanocomposites. In addition, most of the tribological studies investigate adhesive or abrasive wear resistance, whereas studies of erosive wear resistance lag well behind. It was previously shown that the presence of nanoparticles in ZA-27 alloy-based nanocomposites led to a slight increase in erosive wear resistance. Upon discovering that, the aim became to produce micro-nanocomposites that would retain the positive effect of nanoparticles, while further elevating performance, by combining microparticles with nanoparticles. The ZA-27 alloy-based micro-nanocomposites were reinforced with 3 wt. % Al2O3 microparticles (particle size approx. 36 μm) and with four different amounts (0.3, 0.5, 0.7 and 1 wt. %) of Al2O3 nanoparticles (particle size 20–30 nm). Tested materials were produced by the compocasting process, with mechanical alloying pre-processing. Solid particle erosive wear testing, with particle impact angle of 90°, showed that all micro-nanocomposites had significantly increased wear resistance in comparison to the reference material.

Assessment of Mechanical, Chemical, and Biological Properties of Ti-Nb-Zr Alloy for Medical Applications

The purpose of this work is to obtain comprehensive reference data of the Ti-13Nb-13Zr alloy base material: its microstructure, mechanical, and physicochemical properties. In order to obtain extensive information on the tested materials, a number of examination methods were used, including SEM, XRD, and XPS to determine the phases occurring in the material, while mechanical properties were verified with static tensile, compression, and bending tests. Moreover, the alloy’s corrosion resistance in Ringer’s solution and the cytotoxicity were investigated using the MTT test. Studies have shown that this alloy has the structure α’, α, and β phases, indicating that parts of the β phase transformed to α’, which was confirmed by mechanical properties and the shape of fractures. Due to the good mechanical properties (E = 84.1 GPa), high corrosion resistance, as well as the lack of cytotoxicity on MC3T3 and NHDF cells, this alloy meets the requirements for medical implant materials. Ti-13Nb-13Zr alloy can be successfully used in implants, including bone tissue engineering products and dental applications.

Reduction of distortion by using the low transformation temperature effect for high alloy steels in electron beam welding

Residual stress and distortion of welded specimens are issues when it comes to geometrical requirements. The surrounding material prevents the dilatation associated with transformation in the area of heat input resulting in residual stress and distortion due to thermal contraction. In the past few years, low transformation temperature (LTT) material was successfully used as filler wire to reduce residual stress as well as distortion in the weld seam in arc welding processes. High alloy Fe-based filler materials with levels of chromium and nickel ensure a martensitic transformation at reduced temperatures in a low alloy base material. The LTT properties counteract the accumulation of stresses due to thermal contraction with compressive stresses that develop within the transformed region. This work used a high alloy base material in combination with a low alloy filler wire resulting in a microstructure that shows the same properties as LTT weld metals. This in situ alloying allows for an alloy composition tailored to the process. In order to provide a point of reference, comparable welds were made using conventional high alloy filler wire. As a result, the distortion and longitudinal residual stress was significantly reduced compared to welding with conventional filler wire.

Processing and Mechanical Characterization of ADC12 alloy-B4C-RHA Hybrid Composites

The effects of dual particulates addition on the mechanical behaviour of ADC12 alloy composites were studied. Boron carbide (B4C) and rice husk ash (RHA) particulates were used as the reinforcements in the ADC12 alloy base matrix. Hybrid composites were prepared by using liquid melt method, keeping 5 wt. % of B4C reinforcement constant and varying rice husk ash particles in steps of 3 and 6 wt. % in the ADC12 alloy. Samples were tested for microstructural characterization by using SEM and EDS. Mechanical behaviour like hardness, ultimate tensile strength; yield strength, percentage elongation and compression strength were evaluated as per ASTM standards. SEM photographs revealed the uniform distribution of B4C and RHA particulates in the ADC12 alloy and these particles were confirmed by EDS analysis. Further, hardness, tensile and compression properties of base matrix ADC12 alloy was enhanced with the addition of B4C and RHA particulates. Ductility of ADC12 alloy decreased after the incorporation of B4C and RHA particles.

On the Effect of Glassy Coatings on the Wear of a Sliding Contact via Multiphysics Modeling

A recently developed multiphysics computational framework is exercised to predict the wear behavior of two deformable and heat conducting bodies under conditions of sliding contact. This framework enables the solution of a high dimensional thermo-mechanical problem simultaneously and tightly coupled with the associated wear evolution models for each of the wear pair bodies, thus enabling predictions of wear for both of them. Two distinct slider-base pairs are modeled. The first involves an aluminum alloy slider and a copper alloy base. The second is a pair identical to the first except it contains a thin strip of soda lime glass embedded in the surface of the base. The objective of this effort is to establish the effects of this glass layer on the wear of all participating bodies in comparison to the pair that does not contain this layer. The results indicate that while the glass layer has a wear mitigation effect for the stationary base it slightly increases the wear of the slider when compared with the respective bodies when the glass is not present.