Reduction in Fatigue Strength of Arc Welded Aluminium 5083-H111 on Immersion in NaCl

2014 ◽  
Vol 891-892 ◽  
pp. 1469-1475
Author(s):  
Madeleine du Toit ◽  
Kalenda Mutombo
Keyword(s):  
Sea Water ◽  
Base Material ◽  
Fatigue Loading ◽  
Ambient Air ◽  
Fatigue Behaviour ◽  
Design Codes ◽  
Corrosive Environment ◽  
Nacl Solution ◽  
Fatigue Design ◽  
Reference Curves

The design of welded aluminium structures subjected to fatigue loading is usually carried out on the basis of reference fatigue curves published in design codes. The reference curves are usually relevant to dynamic loading in ambient air and make provision for the presence of a corrosive environment by downgrading the detail category for a particular joint type. This investigation studied the corrosion-fatigue behaviour of Al 5083-H111 welded using ER5356 wire. Comparison between experimentally determined fatigue curves and reference fatigue design curves published in Eurocode 9 confirms that 5083-H111 welds display significantly lower reference fatigue strengths than unwelded base material. Immersion in a NaCl solution during testing reduced the reference fatigue strengths even further. The reduction in detail category number recommended in Eurocode 9 for aluminium butt welds on immersion in sea water appears suitable (or even marginally conservative) for the 5XXX series Al-Mg-Mn welds examined in this investigation.

Comparison of Epoxy Coating Degradations Under Impingement Flow and Stationary Immersion

2020 ◽  
Author(s):  
Amin Vedadi ◽  
M. Subbir Parvej ◽  
Xinnan Wang ◽  
Yechun Wang
Keyword(s):  
Wind Turbines ◽  
Sea Water ◽  
Electrochemical Impedance ◽  
Epoxy Coating ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Corrosive Environment ◽  
Nacl Solution ◽  
Offshore Wind Turbines ◽  
The Impact

Abstract Offshore wind turbines are considered as a reliable source of electricity generation. However, due to the large cost of the construction and installation of offshore wind turbines, most wind turbines are designed to operate for more than 20 years. One of the biggest issues which causes a severe damage to the construction of wind turbines is the existence of a very corrosive environment including large mechanical loads applied to the construction by the waves and the high concentration of salt and other chemicals in the sea water. The construction of offshore wind turbine can be divided into four main regions based on the types of exposure to the water and the corrosive environment, including submerged zone, tidal zone, splash zone, and atmospheric zone. In this study, experiments were conducted to compare the impact of impingement flow of 3.5 w.t.% NaCl solution on the epoxy coating samples to the exposure of the same type of samples to a stationary 3.5 w.t.% NaCl solution. Those two exposure conditions correspond to the environments at the top and the bottom part of the submerged zone of offshore wind turbines respectively. Electrochemical Impedance Spectroscopy (EIS) method was used to monitor the degradation of organic coatings. The surface roughness was measured by Atomic Force Microscope (AFM). The roughness of the coated surfaces before and after the exposure was compared. For the two different flow conditions, i.e. impingement flow and stationary immersion, significant differences have been discovered from the EIS results and AFM results. We observed a more severe degradation in the epoxy coatings in impingement flow, and a rougher surface is formed for coating samples subjected to impingement flow.

Evaluation of Fatigue Design Curves for a Double-Side Welded Connection Used in Offshore Applications

2018 ◽  
Author(s):  
José A. F. O. Correia ◽  
Miguel Correia ◽  
Mads Holm ◽  
Julle Ekeborg ◽  
Grzegorz Lesiuk ◽  
...  
Keyword(s):  
Hot Spot ◽  
Fatigue Cracks ◽  
Base Material ◽  
Fatigue Curve ◽  
Offshore Structures ◽  
Design Codes ◽  
Fatigue Design ◽  
Fatigue Model ◽  
Welded Connection ◽  
Fatigue Failures

One of the major concerns in offshore structures are the welded connections where fatigue failures are highly relevant. In many cases of offshore welded connections, the fatigue cracks initiated may grow from the weld to the base material, but also from the root of the weld. In this study, the evaluation of design S-N curves for a double-side welded connection made of S355J2 steel used in offshore applications is proposed. The characteristic fatigue curve of the double-side welded connection is obtained using statistical analyses based either in the ASTM E739 standard as well as the probabilistic fatigue model proposed by Castillo & Fernández-Canteli. This study concludes with a comparison between the experimental fatigue curves obtained and the design S-N curves proposed in design codes for offshore structures. Existing code recommendations are very conservative when comparing the design S-N curves with the proposed new characteristic S-N curves. For the joint under investigation the hot spot and nominal stress approaches yield very similar S-N results.

Fatigue Behaviour of Friction Stir Welded Steel Joints

2014 ◽  
Vol 891-892 ◽  
pp. 1488-1493 ◽  
Author(s):  
José Azevedo ◽  
Virgínia Infante ◽  
Luisa Quintino ◽  
Jorge dos Santos
Keyword(s):  
Base Material ◽  
Welding Process ◽  
Steel Structures ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Welded Steel ◽  
Shipbuilding Industry ◽  
Friction Stir ◽  
Steel Joints

The development and application of friction stir welding (FSW) technology in steel structures in the shipbuilding industry provide an effective tool of achieving superior joint integrity especially where reliability and damage tolerance are of major concerns. Since the shipbuilding components are inevitably subjected to dynamic or cyclic stresses in services, the fatigue properties of the friction stir welded joints must be properly evaluated to ensure the safety and longevity. This research intends to fulfill a clear knowledge gap that exists nowadays and, as such, it is dedicated to the study of welded steel shipbuilding joints in GL-A36 steel, with 4 mm thick. The fatigue resistance of base material and four plates in as-welded condition (using several different parameters, tools and pre-welding conditions) were investigated. The joints culminate globally with defect-free welds, from which tensile, microhardness, and fatigue analyses were performed. The fatigue tests were carried out with a constant amplitude loading, a stress ratio of R=0.1 and frequency between 100 and 120 Hz. The experimental results show the quality of the welding process applied to steel GL-A36 which is reflected in the mechanical properties of joints tested.

Effect of Cr and Zr Addition on the Corrosion Behaviour of Copper in the Chloride Solution

2011 ◽  
Vol 194-196 ◽  
pp. 1253-1256
Author(s):  
Ya Ni Zhang ◽  
Mao Sheng Zheng ◽  
Jie Wu Zhu
Keyword(s):  
Corrosion Resistance ◽  
Chloride Solution ◽  
Corrosion Behaviour ◽  
Pure Copper ◽  
Base Material ◽  
Nacl Solution ◽  
Corrosion Performance ◽  
Zr Addition ◽  
Corrosion Scales ◽  
Better Than

The corrosion behavior of CuCr, CuZr and CuCrZr alloys in NaCl solution is reported in this paper. The corrosion performance has been evaluated in NaCl solution atmosphere. The results show the corrosion resistance of pure copper decrease with the addition of the alloying elements initially. However, in the later exposure stages, the corrosion resistance of CuZr and CuCrZr alloy deteriorates significantly while the corrosion resistance of CuCr alloy is slightly better than that of pure copper. In addition, the results of the electrochemical experiments indicate that the different behavior for the element Cr and Zr in the base material and corrosion scales lead to the change of the corrosion resistance.

Comparison of the Fatigue Performance of Galvanised M72 Bolts With Design Standard Recommendations

2021 ◽  
Author(s):  
Carol Johnston ◽  
Matthew Doré
Keyword(s):  
Fatigue Performance ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Design Codes ◽  
Design Standards ◽  
Threaded Fasteners ◽  
Fatigue Design ◽  
Standard Design ◽  
Wind Turbine Towers ◽  
Thickness Correction

Abstract Now that bolted flanges rather than grouted connections are used to join the transition piece to the monopile in offshore wind turbine towers, many large bolts are being used in applications which subject them to fatigue loads. The bolts in these ring flanges are typically M64 or M72 in size (ie 64mm of 72mm nominal diameter). The fatigue design codes, BS 7608, DNVGL-RP-C203 and Eurocode 3 do provide S-N curves for threaded fasteners, but the reference diameter in those documents is 25mm or 30mm. A thickness correction is provided, to account for larger diameter bolts, but this was originally derived by analysis of the performance of welded joints. It is unclear whether the S-N curves and the recommended thickness correction are appropriate for larger diameter threaded fasteners. The offshore wind industry usually specifies hot dip galvanised bolts, to provide some corrosion protection in the offshore environment. Again, there is uncertainty over whether the S-N curves in fatigue design standards apply to bolts with a galvanised coating. Since the fatigue design codes provide S-N curves for air, free corrosion or seawater with cathodic protection, it is also unclear which of these should be used to predict the fatigue performance of bolts with a galvanised coating. In order to provide data to address these uncertainties, hot-dip galvanised, grade 10.9, M72 bolts from two manufacturers were tested in both air and a seawater environment. In order to represent the conditions experienced by bolts in internal ring flanges, the artificial seawater was sprayed onto the bolts during testing. Tests were conducted with a mean stress corresponding to 70% of the specified minimum 0.2% proof strength of the bolts. Tests were also performed in air, on uncoated M72 bolts, and uncoated M64 bolts for comparison. The results suggest that the current thickness correction in DNVGL RP C203 and BS 7608 is appropriate for M72 bolts. The results in air from the galvanised bolts were below those from uncoated bolts. Although the galvanised results were above the thickness corrected in-air standard design curves (BS7608 Class X -20%, DNVGL Class G and DNVGL ST 0126 FAT 50), they were below the mean curves, suggesting that the performance of galvanised bolts is slightly lower than the existing recommendations.

Chain Out of Plane Bending (OPB) Fatigue Joint Industry Project (JIP) Static Test Program and OPB Interlink Stiffness

2016 ◽  
Author(s):  
Lucile Rampi ◽  
Fata Dewi ◽  
Michel Francois ◽  
Arnaud Gerthoffert ◽  
Pedro Vargas
Keyword(s):  
Fatigue Loading ◽  
Time Frame ◽  
Small Time ◽  
Static Test ◽  
Fatigue Design ◽  
Out Of Plane ◽  
Bending Stresses ◽  
Plane Bending ◽  
Mooring Chain ◽  
Fatigue Mechanism

In 2002, several mooring chains of a deepwater offloading buoy failed prematurely within a very small time frame. These chains were designed according to conventional offshore fatigue assessment using API recommendations. With this first deepwater buoy application, a new mooring chain fatigue mechanism was discovered. High pretension levels combined with significant mooring chain motions caused interlink rotations that generated significant Out of Plane Bending (OPB) fatigue loading. Traditionally, interlink rotations are relatively harmless and generate low bending stresses in the chain links. The intimate mating contact that occurs due to the plastic deformation during the proof loading and the high pretension of the more contemporary mooring designs have been identified as aggravating factors for this phenomenon. A Joint Industry Project (JIP), gathering 26 different companies, was started in 2007 to better understand the Out of Plane Bending (OPB) mooring chain fatigue mechanism and to propose mooring chain fatigue design recommendations. This paper summarizes the quasi static OPB stiffness measurement campaign and the post processing work to derive the OPB interlink stiffness.

scholarly journals Evaluating the Performance of Aluminum Sacrificial Anodes with Different Concentration of Gallium in Artificial Sea Water

Coatings ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 53
Author(s):  
Yuntao Xi ◽  
Mao Jia ◽  
Jun Zhang ◽  
Wanli Zhang ◽  
Daoyong Yang ◽  
...  
Keyword(s):  
Sea Water ◽  
Electrochemical Techniques ◽  
Mg Alloy ◽  
Nacl Solution ◽  
Discharge Performance ◽  
Sacrificial Anodes ◽  
Microstructure Observation ◽  
Discharge Activity ◽  
Anodic Efficiency ◽  
Gallium Content

In this manuscript, the influence of gallium content additions of Al-Zn-In-Mg alloy was investigated through electrochemical techniques and microstructure observation in 3.5 wt% NaCl solution. The results indicated that Al-Zn-In-Mg-0.03Ga alloy has the best discharge performance among all alloys. We propose that this is due to the fact that gallium addition to the Al-4Zn-In-Mg alloy improves the discharge activity of the alloy as well as elevating its anodic efficiency. In particular, the effect of gallium addition to improve discharge activity tends to be a parabolic curve, in which there is an increase when the gallium is first added that rises to the maximum anode current efficiency of about 98.25% whenever gallium content is 0.03 wt%.

scholarly journals THE EFFECT OF BEACH ENVIRONMENT AND SEA WATER ON NICKEL CORROSION RATE AS A COLLIMATOR MATERIAL FOR THE APPLICATION OF BORON NEUTRON CAPTURE THERAPY

2019 ◽  
Vol 21 (3) ◽  
pp. 127
Author(s):  
Hardi Hidayat ◽  
Budi Setyahandana ◽  
Yohannes Sardjono ◽  
Yulwido Adi
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Rate ◽  
Boron Neutron Capture Therapy ◽  
Neutron Capture ◽  
Sea Water ◽  
Base Material ◽  
Coastal Environment ◽  
Corrosion Testing ◽  
Neutron Capture Therapy ◽  
Boron Neutron Capture

The purpose of this study is to determine the value of corrosion rate influenced by coastal environment and seawater to nickel as a collimator base material for the application of boron neutron capture therapy (BNCT). In this research, the authors used 99.9% pure nickel as the reference material. Corrosion testing was carried out to determine the rate of corrosion of nickel as a base material for BNCT. After the specimens were formed, the test specimens were then corroded for 12 weeks, with various conditions such as indoor, outdoor environment, static seawater, and moving seawater. The results of this study indicated that in corrosion testing with indoor condition, the corrosion rate values are 0.61-1.00 mpy. For outdoor condition, the corrosion rate is 0.89-1.34 mpy. Meanwhile, at static seawater conditions, the corrosion rate is 0.97-1.24 mpy. Lastly, for moving seawater condition, the corrosion rate is 1.64-1.91 mpy. The results showed that corrosion resistance was relatively the same for all nickel exposed to corrosion in the coastal environment. Therefore, in regards to corrosion resistance, using nickel as a collimator base material for BNCT applications is considered as safe.Keywords: BNCT, Nickel, Corrosion, Coastal Environtment, Sea Water

scholarly journals A Method for Comparing the Fatigue Performance of Forged AZ80 Magnesium

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1290
Author(s):  
Andrew Gryguć ◽  
Seyed Behzad Behravesh ◽  
Hamid Jahed ◽  
Mary Wells ◽  
Bruce Williams ◽  
...  
Keyword(s):  
Base Material ◽  
Fatigue Behaviour ◽  
Fatigue Properties ◽  
Closed Die Forging ◽  
Geometry Configuration ◽  
Automotive Suspension ◽  
Process Structure ◽  
Durability Performance ◽  
Strength And Ductility ◽  
Structure Properties

A closed die forging process was developed to successfully forge an automotive suspension component from AZ80 Mg at a variety of different forging temperatures (300 °C, 450 °C). The properties of the forged component were compared and contrasted with other research works on forged AZ80 Mg at both an intermediate forging and full-scale component forging level. The monotonic response, as well as the stress and strain-controlled fatigue behaviours, were characterized for the forged materials. Stress, strain and energy-based fatigue data were used as a basis for comparison of the durability performance. The effects of the starting material, forging temperature, forging geometry/configuration were all studied and aided in developing a deeper understanding of the process-structure-properties relationship. In general, there is a larger improvement in the material properties due to forging with cast base material as the microstructural modification which enhances both the strength and ductility is more pronounced. In general, the optimum fatigue properties were achieved by using extruded base-material and forging using a closed-die process at higher strain rates and lower temperatures. The merits and drawbacks of various fatigue damage parameters (FDP’s) were investigated for predicting the fatigue behaviour of die-forged AZ80 Mg components, of those investigated, strain energy density (SED) proved to be the most robust method of comparison.

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