Research

12 pages, 7419 KiB

Open AccessArticle

Study on the Effects of Multiple Laser Shock Peening Treatments on the Electrochemical Corrosion Performance of Welded 316L Stainless Steel Joints

by Yuqin Li, Jinyu Fan, Jianzhong Wen, Xiangfan Nie and Liucheng Zhou

Metals 2022, 12(7), 1215; https://doi.org/10.3390/met12071215 - 19 Jul 2022

Cited by 8 | Viewed by 1575

Abstract

To study the influence of laser shock peening on the electrochemical corrosion resistance of welded 316L stainless steel joints, welded 316L stainless steel joints are treated with different laser shock peening treatments (i.e., one, two, and three times). Our analysis employs electron backscattering [...] Read more.

To study the influence of laser shock peening on the electrochemical corrosion resistance of welded 316L stainless steel joints, welded 316L stainless steel joints are treated with different laser shock peening treatments (i.e., one, two, and three times). Our analysis employs electron backscattering diffraction (EBSD), scanning electron microscopy (SEM), X-ray diffraction (XRD), an X-ray stress meter, and electrochemical corrosion tests to observe and analyze the microstructure, structural composition, residual stress, and corrosion resistance in different areas of the surface of 316L before and after the laser shock peening. The results show that the residual stress distribution of the welded joints is optimized after laser shock peening, with a maximum residual compressive stress near the matrix of 171 MPa. When the number of laser shock peening treatments is two, the corrosion current reaches a minimum of 9.684×10⁻⁷ A/cm², and optimal pitting resistance is obtained. However, when the number of laser shock peening treatments is further increased to three, the corrosion current increase and the pitting resistance decreases. In summary, the electrochemical corrosion resistance of the welded joints effectively improves after laser shock peening, but its performance begins to decline after three repeated shocks, which is related to the combined effects of stress change and microstructure phase transformation. Full article

(This article belongs to the Special Issue Investigations on Mechanical Properties and Corrosion Resistance of Alloys and Compounds)

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15 pages, 4123 KiB

Open AccessArticle

Alternative Liquid-Assisted Sintering of Al/Cu Composites Using Selected Powders of As-Cast Al-Zn Alloy

by Eder L. Ortiz, Wislei R. Osório, Ausdinir D. Bortolozo and Giovana S. Padilha

Metals 2022, 12(6), 962; https://doi.org/10.3390/met12060962 - 03 Jun 2022

Cited by 1 | Viewed by 1618

Abstract

Al and its alloys constitute one of the most versatile, economical, and attractive materials for a wide range of applications. The 7xxx and 2xxx series alloys achieve the highest mechanical strength among the aluminum alloys. In this investigation, powder metallurgy is used to [...] Read more.

Al and its alloys constitute one of the most versatile, economical, and attractive materials for a wide range of applications. The 7xxx and 2xxx series alloys achieve the highest mechanical strength among the aluminum alloys. In this investigation, powder metallurgy is used to characterize the microstructural and mechanical properties of a noncommercial Al6Cu5Zn alloy. Initial powder sizes are determined, and the best conditions are obtained for distribution between 75 and 106 μm. The samples are sintered at 585 °C, 600 °C and 615 °C for 0.5, 1.5 h and 3 h. Similar mechanical behavior to that of the as-cast Al-Cu-based alloys is attained (~125 MPa) for the samples sintered at 615 °C for 3 h. In terms of a reduction in energy consumption and in the metal fumes commonly evidenced by foundry applications, Al-Zn powders have the potential to be associated with Al and Cu powders in an Al6Cu5Zn composite constitution. Full article

(This article belongs to the Special Issue Investigations on Mechanical Properties and Corrosion Resistance of Alloys and Compounds)

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Graphical abstract

31 pages, 6813 KiB

Open AccessEditor’s ChoiceArticle

The Holes of Zn Phosphate and Hot Dip Galvanizing on Electrochemical Behaviors of Multi-Coatings on Steel Substrates

by Thiago Duarte, Yuri A. Meyer and Wislei R. Osório

Metals 2022, 12(5), 863; https://doi.org/10.3390/met12050863 - 18 May 2022

Cited by 26 | Viewed by 2390

Abstract

The aim of this investigation is focused on the evaluation of distinctive coatings commonly applied in the automotive industry. The resulting corrosion behavior is analyzed by using electrochemical impedance spectroscopy (EIS), equivalent circuit (EC) and potentiodynamic polarization curves. The novelty concerns a comparison [...] Read more.

The aim of this investigation is focused on the evaluation of distinctive coatings commonly applied in the automotive industry. The resulting corrosion behavior is analyzed by using electrochemical impedance spectroscopy (EIS), equivalent circuit (EC) and potentiodynamic polarization curves. The novelty concerns a comparison between tricationic phosphate (TCP), cataphoretic electrodeposition (CED) of an epoxy layer, TCP + CED and HDG (hot-dip galvanized) + TCP + CED multi-coatings. Both the naturally deposited and defect-induced damage (incision) coatings are examined. The experimental impedance parameters and corrosion current densities indicate that multi-coating system (HDG + TCP + CED layers) provides better protection. Both planar and porous electrode behaviors are responsible to predict the corrosion mechanism of the majority of samples examined. Although induced-damage samples reveal that corrosion resistances decreased up to 10×, when compared with no damaged samples, the same trend of the corrosion protection is maintained, i.e., TCP < CED < TCP + CED < HDG + TCP + CED. It is also found that the same trend verified by using electrochemical parameters is also observed when samples are subjected under salt spray condition (500 h). It is also found that porous electrode behavior is not a deleterious aspect to corrosion resistance. It is more intimately associated with initial thickness coating, while corrosion resistance is associated with adhesion of the CED layer on TCP coating. The results of relative cost-to-efficiency to relative coating density ratios are associated with fact that a CED coating is necessary to top and clear coating applications and the TCP + CED and the HDG/TCP + CED coating systems exhibit the best results. Full article

(This article belongs to the Special Issue Investigations on Mechanical Properties and Corrosion Resistance of Alloys and Compounds)

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8 pages, 5218 KiB

Open AccessEditor’s ChoiceArticle

Electrochemical Corrosion Resistance of Mg Alloy ZK60 in Different Planes with Respect to Extrusion Direction

by G. Keerthiga, Dandapani Vijayshankar, MJNV Prasad, Mirco Peron, Jafar Albinmousa and RK Singh Raman

Metals 2022, 12(5), 782; https://doi.org/10.3390/met12050782 - 30 Apr 2022

Cited by 6 | Viewed by 1895

Abstract

The electrochemical corrosion resistance of a Mg-Zn-Zr alloy, ZK60, in different planes with respect to the extrusion direction was investigated in 3.5 wt% NaCl. The motivation of this study lies in the influence of extrusion on the grain size, texture and precipitation characteristics [...] Read more.

The electrochemical corrosion resistance of a Mg-Zn-Zr alloy, ZK60, in different planes with respect to the extrusion direction was investigated in 3.5 wt% NaCl. The motivation of this study lies in the influence of extrusion on the grain size, texture and precipitation characteristics of magnesium alloys, and the profound role of these characteristics in the corrosion resistance of the alloys. Corrosion resistance was found to be considerably superior in the plane transverse to the extrusion direction (TD) than in the extrusion direction (ED) or normal to the extrusion direction (ND). The difference in the corrosion resistance was attributed to the variations in microstructural features in the TD, ED and ND directions. Full article

(This article belongs to the Special Issue Investigations on Mechanical Properties and Corrosion Resistance of Alloys and Compounds)

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16 pages, 6055 KiB

Open AccessArticle

The Laser Deposited Nickel-Aluminum Bronze Coatings on SUS630 Stainless Steel and Its Corrosion Resistance in 3.5 wt.% NaCl Solution

by Lu Zhao, Kailun Li, Jun Yao, Yixiang Yuan and Baorui Du

Metals 2022, 12(5), 781; https://doi.org/10.3390/met12050781 - 30 Apr 2022

Cited by 2 | Viewed by 1753

Abstract

In this work, three composite structures of nickel-aluminum bronze (NAB) bonded with SUS630 stainless steel with different intermediate layers were fabricated by laser deposition. The microstructure and corrosion behavior of NAB in 3.5 wt.% NaCl solution were studied. The NAB coating directly deposited [...] Read more.

In this work, three composite structures of nickel-aluminum bronze (NAB) bonded with SUS630 stainless steel with different intermediate layers were fabricated by laser deposition. The microstructure and corrosion behavior of NAB in 3.5 wt.% NaCl solution were studied. The NAB coating directly deposited on steel substrate contains a large number of Fe-rich dendrites due to the dilution by laser energy and the Cu-Fe liquid phase separation characteristics. The microstructures of NAB were independent and isolated well from the steel substrate when the nickel intermediate layer was applied. Immersion corrosion and electrochemical tests indicated that the composite structure with the nickel intermediate layer presented better corrosion resistance than direct deposited the NAB coating, especially with the NiCr alloy intermediate layer, which led to a shallower corrosion depth and formed a denser layer of protective corrosion products. Full article

(This article belongs to the Special Issue Investigations on Mechanical Properties and Corrosion Resistance of Alloys and Compounds)

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32 pages, 7463 KiB

Open AccessArticle

EIS Investigation of the Corrosion Behavior of Steel Bars Embedded into Modified Concretes with Eggshell Contents

by Yuri Alexandre Meyer, Izabella Menezes, Rodrigo Silva Bonatti, Ausdinir Danilo Bortolozo and Wislei Riuper Osório

Metals 2022, 12(3), 417; https://doi.org/10.3390/met12030417 - 26 Feb 2022

Cited by 28 | Viewed by 2810

Abstract

This investigation is focused on evaluation of the corrosion behavior of embedded steel bars (SB) into concretes. Conventional and modified concretes with eggshell are prepared. Although the effect of calcium carbonate on mechanical behavior is recognized and reported, their effects as eggshell (ES) [...] Read more.

This investigation is focused on evaluation of the corrosion behavior of embedded steel bars (SB) into concretes. Conventional and modified concretes with eggshell are prepared. Although the effect of calcium carbonate on mechanical behavior is recognized and reported, their effects as eggshell (ES) particles replacing portions of sand and cement contents are reasonably scarce. Corrosion behavior is evaluated by electrochemical impedance spectroscopy (EIS) and the potentiodynamic polarization technique. Equivalent circuit and porous electrode behavior are also considered. The novelty concerns a promising use of concrete with ES content to maintain corrosion resistance concatenated with reasonable structural properties. For this purpose, three distinct concrete mixtures are proposed, i.e., a reference and two modified concretes. One replaces 10 wt.% with cement and another 10 wt.% with sand content. It is found that porous electrode behavior helps to predict the corrosion mechanism. Finer ES particles in concrete mixture provides a rapidly passivation on rebar. This reflects positively in corrosion current density after long-term immersion. Additionally, an environmentally friendly aspect associated with economical factor constitutes a promise use of the concrete. Full article

(This article belongs to the Special Issue Investigations on Mechanical Properties and Corrosion Resistance of Alloys and Compounds)

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17 pages, 19688 KiB

Open AccessFeature PaperArticle

Recrystallization and Grain Growth of AISI 904L Super-Austenitic Stainless Steel: A Multivariate Regression Approach

by Giulia Stornelli, Matteo Gaggiotti, Silvia Mancini, Giuseppe Napoli, Claudia Rocchi, Chiara Tirasso and Andrea Di Schino

Metals 2022, 12(2), 200; https://doi.org/10.3390/met12020200 - 21 Jan 2022

Cited by 24 | Viewed by 3134

Abstract

AISI 904L is a super-austenitic stainless steel that is remarkable for its mechanical properties and high corrosion resistance, which strictly depend on its chemical composition and microstructural features. The recrystallization process and grain growth phenomena play key roles in achieving high levels of [...] Read more.

AISI 904L is a super-austenitic stainless steel that is remarkable for its mechanical properties and high corrosion resistance, which strictly depend on its chemical composition and microstructural features. The recrystallization process and grain growth phenomena play key roles in achieving high levels of material quality, as often requested by customers for specific applications. In this paper, the evolution of the microstructure and hardness values after cold rolling and subsequent annealing is reported, with the aim of optimizing the thermomechanical treatment conditions and improving the efficiency of the production process. The investigation was focused on three different cold reduction ratios (50%, 70% and 80%), while combining different annealing temperatures (950, 1050 and 1150 °C) and soaking times (in the range of 20–180 s. The test results were organized using a data analysis and statistical tool, which was able to show the correlation between the different variables and the impacts of these on recrystallization and grain growth processes. For low treatment temperatures, the tested soaking times led to partial recrystallization, making this condition industrially unattractive. Instead, for the higher temperature, full recrystallization was achieved over a short time (20–40 s), depending on the reduction ratio. Regarding the grain growth behavior, it was found to be independent of the reduction ratio; for each treatment temperature, the grain growth showed a linear trend as a function of the soaking time only. Moreover, the static recrystallization kinetics were analyzed using a statistical analysis software program that was able to provide evidence indicating the most and least influential parameters in the process. In particular, taking into consideration the hardness values as output data, the temperature and soaking time were revealed to have major effects as compared with the reduction ratio, which was excluded from the statistical analysis. The prediction approach allowed us to formulate a regression equation in order to correlate the response and terms. Moreover, a response optimizer was used to predict the best solution to get as close as possible to the hardness target required by the market. Full article

(This article belongs to the Special Issue Investigations on Mechanical Properties and Corrosion Resistance of Alloys and Compounds)

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19 pages, 22388 KiB

Open AccessEditor’s ChoiceArticle

Corrosion Behavior of CW6MC Nickel Cast Alloy (Inconel 625) Welded by Shielded Metal Arc Welding

by Guilherme dos Santos Vacchi, Rodrigo Silva, Cristie Luis Kugelmeier, Claudio Beserra Martins Júnior, Isabela Dainezi, José Henrique Alano, Anibal de Andrade Mendes Filho, Wislei Riuper Ramos Osório and Carlos Alberto Della Rovere

Metals 2021, 11(8), 1286; https://doi.org/10.3390/met11081286 - 15 Aug 2021

Cited by 2 | Viewed by 3467

Abstract

The aim of this study concerns the effect of multi-pass shielded metal arc welding (SMAW) on the corrosion behavior of CW6MC cast nickel alloy. Using optical and SEM techniques the welded joint is analyzed. Vickers microhardness mapping and potentiodynamic polarization in NaCl and [...] Read more.

The aim of this study concerns the effect of multi-pass shielded metal arc welding (SMAW) on the corrosion behavior of CW6MC cast nickel alloy. Using optical and SEM techniques the welded joint is analyzed. Vickers microhardness mapping and potentiodynamic polarization in NaCl and H₂SO₄ solutions are also evaluated. Both the Laves phase and NbC-type carbides are identified in the base metal (BM) and weld metal (WM) regions. The main microstructural difference observed between these regions is the morphology aspect and fineness of the dendritic arrays. The welding process promotes the finer columnar grains formation with refined intermetallic particles in the WM than equiaxed grains of the BM, which in turn results in higher microhardness values in the former region. However, no substantial changes were observed in the corrosion behavior between the BM and WM regions, considering both acid and saline media. Nevertheless, during the multi-pass SMAW process, some non-metallic micrometric inclusions (Mo and S-rich regions) can be constituted to occur in the WM region. This is associated with a significant drop in the corrosion performance of this region when the electrochemical tests are evaluated. Full article

(This article belongs to the Special Issue Investigations on Mechanical Properties and Corrosion Resistance of Alloys and Compounds)

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