scholarly journals A Comparative Study of Corrosion AA6061 and AlSi10Mg Alloys Produced by Extruded and Additive Manufacturing

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5793
Author(s):  
Francisco Estupiñan-López ◽  
Citlalli Gaona-Tiburcio ◽  
Jesús Jáquez-Muñoz ◽  
Patricia Zambrano-Robledo ◽  
Erick Maldonado-Bandala ◽  
...  
Keyword(s):  
Time Series ◽  
Statistical Analysis ◽  
Additive Manufacturing ◽  
Spectral Density ◽  
Corrosion Behavior ◽  
Room Temperature ◽  
Electrochemical Noise ◽  
Laser Melting ◽  
Hilbert Huang Transform ◽  
Density Analysis

The aim of this work was to evaluate the corrosion behavior of the AA6061 and AlSi10Mg alloys produced by extruded and additive manufacturing (selective laser melting, SLM). Alloys were immersed in two electrolytes in H2O and 3.5 wt. % NaCl solutions at room temperature and their corrosion behavior was studied by electrochemical noise technique (EN). Three different methods filtered EN signals, and the statistical analysis was employed to obtain Rn, the localization index (LI), Kurtosis, skew, and the potential spectral density analysis (PSD). The Energy Dispersion Plots (EDP) of wavelets method was employed to determine the type of corrosion and the Hilbert–Huang Transform (HHT), analyzing the Hilbert Spectra. The result indicated that the amplitude of the transients in the time series in potential and current is greater in the AlSi10Mg alloy manufactured by additive manufacturing. The amplitude of the transients decreases in both alloys (AA6061 and AlSi10Mg) as time increases.

scholarly journals Characteristics of extreme heavy precipitation events occurring in the area of Cracow (Poland)

2014 ◽  
Vol 9 (No. 4) ◽  
pp. 182-191 ◽  
Author(s):  
A. Walega ◽  
B. Michalec
Keyword(s):  
Time Series ◽  
Probability Distribution ◽  
Spectral Density ◽  
Autocorrelation Function ◽  
Heavy Precipitation ◽  
Botanical Garden ◽  
Maximum Precipitation ◽  
Density Analysis ◽  
Increasing Precipitation ◽  
Precipitation Events

The variability of extremely heavy precipitation events with duration of 120 min occurring in the area of Cracow, southern Poland was assessed. The analysis was performed using time series of maximum annual precipitation events with durations t = 5, 10, 15, 30, 60, and 120 min, recorded at the Botanical Garden station at the Jagiellonian University in the period of 1906–1990. The periodicity of precipitation was analyzed using the autocorrelation function and Fourier spectral density analysis. The Probable Maximum Precipitation (PMP) was calculated by Hershfield’s statistical method. The analysis of the autocorrelation function of sequences and the Fourier spectral density revealed a clear periodicity of the maximum precipitation. For precipitation with t = 60 min, the maximum values occur every 9 years, but also shorter periods (3-year) may be observed. The PMP values calculated for Cracow differ significantly from the values calculated using the probability distribution, as well as from the ones observed and they increase with increasing precipitation duration. The differences between the PMP and probable as well as observed precipitation tend to decrease with increasing duration of precipitation.

scholarly journals Electrochemical Noise Analysis of the Corrosion of Titanium Alloys in NaCl and H2SO4 Solutions

Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 105
Author(s):  
Jesús Manuel Jáquez-Muñoz ◽  
Citlalli Gaona-Tiburcio ◽  
Jose Cabral-Miramontes ◽  
Demetrio Nieves-Mendoza ◽  
Erick Maldonado-Bandala ◽  
...  
Keyword(s):  
Titanium Alloys ◽  
Electrochemical Noise ◽  
Noise Analysis ◽  
Passive Layer ◽  
Polynomial Method ◽  
Nacl Solution ◽  
Hilbert Huang Transform ◽  
Ti Alloys ◽  
Density Analysis ◽  
Corrosive Environments

Titanium alloys have been used in aerospace, aeronautic, automotive, biomedical, structural, and other applications because titanium alloys have less density than materials like steel and support higher stress than Al-alloys. However, components made of titanium alloys are exposed to corrosive environments, the most common being industrial and marine atmospheres. This research shows the corrosion behavior of three titanium alloys, specifically Ti-CP2, Ti-6Al-2Sn-4Zr-2Mo, and Ti-6Al-4V with α, near α, and α + β alloys phases. Alloys were exposed in two electrolytes to a 3.5 wt. % H2SO4 and NaCl solution at room temperature, and their electrochemical behavior was studied by electrochemical noise technique (EN) according to ASTM ASTM-G199 standard. EN signal was filtered by three different methods, and the polynomial method was employed to obtain Rn, kurtosis, skew, and the potential spectral density analysis (PSD). The wavelets method was used, from which energy dispersion plots were obtained. The last method was Hilbert–Huang Transform (HHT), where Hilbert Spectra were analyzed. Results indicated that Rn compared with PSD showed that Ti-6Al-2Sn-4Zr-2Mo presented less dissolution in both electrolytes. Statistical methods showed that the passive layer created on Ti alloys’ surfaces is unstable; this condition is notable for Ti-6Al-2Sn-4Zr-2Mo in NaCl solution.

scholarly journals Studying the Microstructural Effect of Selective Laser Melting and Electropolishing on the Performance of Maraging Steel

2021 ◽  
Author(s):  
D. Ahmadkhaniha ◽  
H. Möller ◽  
C. Zanella
Keyword(s):  
Surface Roughness ◽  
Additive Manufacturing ◽  
Maraging Steel ◽  
Selective Laser Melting ◽  
Cross Section ◽  
Corrosion Behavior ◽  
Main Role ◽  
Laser Melting ◽  
Heat Treated ◽  
Manufacturing Technologies

AbstractSelective laser melting is one of the additive manufacturing technologies that have been known for building various and complicated shapes. Despite numerous advantages of additive manufacturing technologies, they strongly influence the microstructure and typically show a relatively high surface roughness. In this study, maraging steel was produced by selective laser melting (SLM), and its microstructure, hardness and corrosion behavior before and after heat treatment were studied and compared to traditionally manufactured ones (wrought, forged samples). In addition, the effect of electropolishing on the surface roughness was evaluated. The microstructural study was carried out by scanning electron microscopy equipped with electron backscattered diffraction in three different sections: parallel to the top surface (xy), transverse cross section (xz) and longitudinal cross section (yz). The same characterization was applied to heat-treated samples, austenitized and quenched as well as the aged ones. The results showed that selective laser melting produced a fine grain martensitic structure (in the as-printed condition) with a surface roughness (Ra) of about 10 µm. There was no sign of preferred texture or anisotropy in the microstructure of as-print SLM materials. The SLM microstructure was similar in all 3 sections (xy, xz and yz). Despite finer microstructure, nano-hardness and corrosion behavior of SLM and conventional wrought maraging steel in heat-treated conditions were similar. Aging resulted in the maximum nano-hardness and the minimum corrosion potential values. Precipitation has the main role in both hardness and corrosion behavior. Electropolishing was optimized and reduced the surface roughness (Ra) by 65%.

scholarly journals Improving surface quality in selective laser melting based tool making

2021 ◽  
Author(s):  
Filippo Simoni ◽  
Andrea Huxol ◽  
Franz-Josef Villmer
Keyword(s):  
Surface Roughness ◽  
Additive Manufacturing ◽  
Surface Quality ◽  
Selective Laser Melting ◽  
Melting Process ◽  
Laser Remelting ◽  
Laser Melting ◽  
Great Cost ◽  
Starting Point ◽  
Processing Techniques

AbstractIn the last years, Additive Manufacturing, thanks to its capability of continuous improvements in performance and cost-efficiency, was able to partly replace and redefine well-established manufacturing processes. This research is based on the idea to achieve great cost and operational benefits especially in the field of tool making for injection molding by combining traditional and additive manufacturing in one process chain. Special attention is given to the surface quality in terms of surface roughness and its optimization directly in the Selective Laser Melting process. This article presents the possibility for a remelting process of the SLM parts as a way to optimize the surfaces of the produced parts. The influence of laser remelting on the surface roughness of the parts is analyzed while varying machine parameters like laser power and scan settings. Laser remelting with optimized parameter settings considerably improves the surface quality of SLM parts and is a great starting point for further post-processing techniques, which require a low initial value of surface roughness.

scholarly journals Proposal for Tower Crane Productivity Indicators Based on Data Analysis in the Era of Construction 4.0

Buildings ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 21
Author(s):  
Thomas Danel ◽  
Zoubeir Lafhaj ◽  
Anand Puppala ◽  
Sophie Lienard ◽  
Philippe Richard
Keyword(s):  
Time Series ◽  
Data Analysis ◽  
Statistical Analysis ◽  
Data Collection ◽  
Structural Phase ◽  
Sampling Technique ◽  
Construction Site ◽  
Data Logger ◽  
Tower Crane ◽  
Productivity Indicators

This article proposes a methodology to measure the productivity of a construction site through the analysis of tower crane data. These data were obtained from a data logger that records a time series of spatial and load data from the lifting machine during the structural phase of a construction project. The first step was data collection, followed by preparation, which consisted of formatting and cleaning the dataset. Then, a visualization step identified which data was the most meaningful for the practitioners. From that, the activity of the tower crane was measured by extracting effective lifting operations using the load signal essentially. Having used such a sampling technique allows statistical analysis on the duration, load, and curvilinear distance of every extracted lifting operation. The build statistical distribution and indicators were finally used to compare construction site productivity.

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