Effects of Heat Treatments on Corrosion Behavior of Mg AT72 Alloy

2013 ◽  
Vol 747-748 ◽  
pp. 230-237 ◽  
Author(s):  
Zhi Qin Wang ◽  
De Jiang Li ◽  
Xiao Qin Zeng ◽  
Xiao Mei Wu ◽  
Wen Jiang Ding
Keyword(s):  
Heat Treatment ◽  
Hydrogen Evolution ◽  
High Vacuum ◽  
Treatment Method ◽  
Optical Microscope ◽  
Heat Treatments ◽  
Open Circuit ◽  
Second Phase ◽  
Corrosion Properties ◽  
Phase Phase

The effects of heat treatments, including T4, T5, T6 treatments, on corrosion behaviors of Mg-7Al-2Sn (AT72) alloy processed by high vacuum die casting have been investigated. The optical microscope, scanning electron microscope observations were used to analyze the microstructures, especially the distribution of second phase, phase contents and grain size. The hydrogen evolution tests, electrochemical methods including open circuit potential curves and polarization curves were used to describe the corrosion properties as well. The results indicated that different heat treatments had influence on microstructures, especially distribution of second phase, phase contents and grain sizes. The existence of second phase had a relationship with corrosion properties, in which the as-cast samples showed low corrosion rate in hydrogen evolution tests while the heat treatment methods had little impact on improving corrosion resistance. The electrochemical analyses also agreed with this observation. Based on these results, the optimized heat treatment method for corrosion resistant AT72 magnesium alloy has been established.

Experimental study of the mechanical and corrosion properties of ethyl silicate resin applied on low carbon steel

2021 ◽  
Vol 2 (108) ◽  
pp. 68-74
Author(s):  
M. Ali ◽  
J.H. Mohmmed ◽  
A.A. Zainulabdeen
Keyword(s):  
Heat Treatment ◽  
Carbon Steel ◽  
Open Circuit Potential ◽  
Low Carbon Steel ◽  
Open Circuit ◽  
Treatment Temperature ◽  
Ethyl Silicate ◽  
Low Carbon ◽  
Corrosion Properties ◽  
Mixture Ratio

Purpose: This work aimed at evaluating the properties of the ethyl silicate-based coating that can be applied on low carbon steel. Design/methodology/approach: Two mixture ratio types (2:1, and 3:2) of resin and hardener respectively were used to prepared two specimen models (A and B). Findings: It found that some mechanical properties (tensile, hardness, and impact strength) of ethyl silicate resin were evaluated according to standard criteria. Research limitations/implications: The effect of heat treatments at various temperatures (100, 150, and 200°C) and holding at different times (10, 20 & 30) min on hardness was investigated. Practical implications: Moreover, an open circuit potential corrosion test with a solution of 3.5% Sodium Chloride at room temperature and 60°C was used to determine the corrosion resistance of low carbon steel specimens coated with the two mixture types. Originality/value: The effects of mixture ratios (for resin and hardener) and heat treatment conditions on properties of ethyl silicate-based coating were studied. From obtained results, acceptable values of tensile, hardness, and toughness were recorded. Increasing heat treatment temperature and holding time leads to enhance hardness for both model types. An open circuit potential (OCP) tests show that there is an enhancement of protective properties of ethyl silicate coatings with mixture type B in comparison with type A was achieved. Generally, the results indicate that specimen model B has higher properties as compared with specimen model A.

scholarly journals Corrosion Behavior of As-Cast Binary Mg-Dy Alloys

2011 ◽  
Vol 690 ◽  
pp. 417-421 ◽  
Author(s):  
Lei Yang ◽  
Frank Feyerabend ◽  
Karl Ulrich Kainer ◽  
Regine Willumeit ◽  
Norbert Hort
Keyword(s):  
Corrosion Rate ◽  
Optical Microscope ◽  
Direct Chill ◽  
Second Phase ◽  
Alloying Element ◽  
High Solubility ◽  
Corrosion Properties ◽  
Corrosion Morphology ◽  
Filiform Corrosion ◽  
Very High

The addition of rare earth elements (REE) is an effective way to improve the corrosion properties of magnesium alloys. Dysprosium has a very high solubility in Mg (25.3 wt.% at 561 °C) and could therefore be a promising alloying element for Mg based implants. In this study, four binary Mg-xDy (x=5, 10, 15 and 20 in wt.%) alloys were prepared by permanent mould direct chill casting. Microstructure and Dy distribution were investigated using optical microscope and EDX analysis. Corrosion rate was measured with hydrogen evolution method and corrosion morphology was observed after immersion for different time in 0.9 wt% NaCl solution with optical and SEM. The results show that with the increase of Dy, the amount of Dy in Mg matrix and area of Dy segregation are both increased. At the same time, the amount of second phase is also increased. Filiform corrosion is reduced while pitting corrosion is increased with the increment of Dy. As a result, lowest corrosion rate is obtained at Mg-10Dy alloy.

Alkaline corrosion properties of laser-clad aluminum/titanium coatings

2015 ◽  
Vol 62 (1) ◽  
pp. 37-47
Author(s):  
Martin Aggerbeck ◽  
Alexis Herbreteau ◽  
Marleen Rombouts ◽  
Jo Verwimp ◽  
Rajan Ambat
Keyword(s):  
Heat Treatment ◽  
Automobile Industry ◽  
Aluminum Matrix ◽  
Optical Microscope ◽  
Titanium Concentration ◽  
Corrosion Properties ◽  
Content Type ◽  
X Ray ◽  
Alkaline Conditions ◽  
Alkaline Corrosion

Purpose – The purpose of this paper is to study the use of titanium as a protecting element for aluminum in alkaline conditions. Design/methodology/approach – Aluminum coatings containing up to 20 weight per cent Ti6Al4V were produced using laser cladding and were investigated using light optical microscope, scanning electron microscope – energy-dispersive X-ray spectroscopy and X-Ray Diffraction, together with alkaline exposure tests and potentiodynamic measurements at pH 13.5. Findings – Cladding resulted in a heterogeneous solidification microstructure containing an aluminum matrix with supersaturated titanium (<1 weight per cent), Al3Ti intermetallics and large partially undissolved Ti6Al4V particles. Heat treatment lowered the titanium concentration in the aluminum matrix, changed the shape of the Al3Ti precipitates and increased the degree of dissolution of the Ti6Al4V particles. Corrosion testing showed significant localized dissolution of the aluminum matrix. Research limitations/implications – Increased titanium concentration and heat treatment gave improved alkaline corrosion properties. At pH 13.5, the Al3Ti phases were protected, while the aluminum matrix corroded. Practical implications – For alkaline corrosion-protection of aluminum in the automobile industry, titanium might be useful at pH values below 13.5 or by using other coating techniques. Originality/value – This is the first study testing the use of titanium as a protective element of aluminum in stringent alkaline conditions.

Effects of Surface Oxide Coating on Corrosion Behavior of Ti-1023/LY12 Galvanic Couple

2013 ◽  
Vol 668 ◽  
pp. 880-884 ◽  
Author(s):  
Jun Xiu Shi ◽  
Jian Hua Liu
Keyword(s):  
Corrosion Behavior ◽  
Galvanic Corrosion ◽  
Oxide Coating ◽  
Optical Microscope ◽  
Open Circuit ◽  
Localized Corrosion ◽  
Corrosion Attack ◽  
Corrosion Properties ◽  
Corrosion Morphology ◽  
Galvanic Couple

Galvanic corrosion behavior of Ti-1023 titanium alloy coupled to LY12 aluminum alloy was investigated in 3.5% NaCl solution. Particular attention was given to the effect of anodized coatings on corrosion behaviors of Ti-1023/LY12 galvanic couple. Galvanic test was conducted on the following couples: Ti-1023/LY12, Ti-1023/anodized LY12 and anodized Ti-1023/anodized LY12, respectively. Corrosion properties including open circuit potential (Eoc) of each material, galvanic corrosion potential (Eg) and galvanic corrosion current (Ig) of the couples were monitored. Corrosion morphology was observed by optical microscope (OM) and corrosion mechanisms were analyzed and discussed. It was showed that anodized coatings significantly decreased Eg and Īg of the couples and provide effective protection of the anode from suffering corrosion attack. Only slight localized corrosion was detected on anodized LY12 alloy in the two anodized couples and the LY12 in anodized Ti-1023/anodized LY12 couple was found to be least susceptible to galvanic corrosion. The LY12 alloy in the bare couple: Ti-1023/LY12, was found to be highly susceptible to galvanic corrosion and suffered severe uniform and localized corrosion attack

Heat Treatment, Mechanical Properties and Microstructure of T-Joint Steel Arc Welded

2018 ◽  
Vol 876 ◽  
pp. 36-40
Author(s):  
Yustiasih Purwaningrum ◽  
Dwi Darmawan ◽  
Panji Lukman Tirta Kusuma
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Tensile Strength ◽  
Weld Metal ◽  
Testing Machine ◽  
Optical Microscope ◽  
Heat Treatments ◽  
Tensile Testing Machine ◽  
Weld Metals ◽  
Quenching Process

Heat treatment of T-Joint’s steel arc welded are performed are investigated in this research. The heat treatment process that used were annealing and quenching. The microstructure was investigated by optical microscope. The mechanical behavior of the samples was investigated using universal tensile testing machine for tensile test and Microvickers hardness method for hardness testing. The microstructure of welding zone of welding metals with various heat treatments is grain boundary ferrite, Widmanstatten ferrite and acicular ferrite. The weld metal with quenching treatment has a highest tensile strength with tensile strength 197.97 Mpa. The quenching process increases the tensile strength by 49.58 %. The distortion value in weld metal without heat treatment, quenching and annealing is 0.11mm; 0.04 mm and 0.08 mm respectively. The hardness number of weld metals with quenching process have a highest number base metal, HAZ and weld metals. Results showed that the mechanical properties of T-joints steel arc welded can be improved by various heat treatments.

scholarly journals Heat Treatments Extend Shelf-life of Tomato Fruit

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 786D-786 ◽  
Author(s):  
R.E. McDonald ◽  
T.G. McCollum ◽  
E.A. Baldwin
Keyword(s):  
Heat Treatment ◽  
Tomato Fruit ◽  
Chilling Injury ◽  
Treatment Method ◽  
Heat Treatments ◽  
Internal Quality ◽  
Color Development ◽  
Lycopene Content ◽  
Ripe Stage ◽  
Heat Treatment Method

Mature, green tomatoes were either gassed or not gassed with C2H4 for 24 h, immersed in 42C water for 60 min, or held in 38C air for 48 h or not treated, and then stored at either 2C or 13C for 14 days before ripening at 20C. During ripening, the fruit were evaluated for color development, internal quality, and decay and for volatiles when full ripe. Both high-temperature treatments reduced chilling injury and inhibited decay. Days to ripen after removal from storage at 2C or 13C was not influenced by heat treatment method. Color development, lycopene content, and internal quality characteristics of fruit were similar at the ripe stage, irrespective of heat treatment. Of 15 volatiles analyzed, seven showed decreased levels of concentrations as a result of C2H4 gassing, nine showed decreased levels when stored at 2C prior to ripening, and most were unaffected by the heat treatments. Heat treatments appear to be beneficial for maintaining tomato fruit quality.

Effects of Ti-1023 Anodized Coating on Corrosion Behavior of Ti-1023/30CrMnSiA and Ti-1023/LY12 Galvanic Couples

2007 ◽  
Vol 546-549 ◽  
pp. 1821-1826
Author(s):  
Jian Hua Liu ◽  
Jun Xiu Shi ◽  
Song Mei Li ◽  
Jun Lan Yi
Keyword(s):  
Corrosion Potential ◽  
Galvanic Corrosion ◽  
Corrosion Current ◽  
Optical Microscope ◽  
Open Circuit ◽  
Corrosion Properties ◽  
Corrosion Morphology ◽  
Average Value ◽  
Galvanic Couples ◽  
Corrosion Mechanisms

Galvanic properties were evaluated on bare and anodized Ti-1023 titanium alloy which coupled to Ni-electroplated, Zn-electroplated, Cd-electroplated 30CrMnSiA and anodized LY12, respectively. Corrosion properties including open circuit potential (Eoc) of each material, galvanic corrosion potential (Eg), and corrosion current (Ig) of the couples were monitored in conjunction with a Model 263A potentiostat system. Corrosion current density (Īg) and average value of corrosion potential (Ēg) were calculated from Ig-time and Eg-time curves, respectively. Corrosion morphology was observed on a optical microscope (OM) and corrosion mechanisms were analyzed and discussed. The corrosion resistance of Ti-1023/LY12 couple was significantly improved by Ti-1023 anodized coating. However, the coating accelerated the dissolve of the three electroplated coatings in the other galvanic couples, resulting in a heavy corrosion attack on 30CrMnSiA steel.

Influence of heat treatment on the corrosion properties of CuAlMn shape memory alloys

2019 ◽  
Vol 37 (6) ◽  
pp. 579-589 ◽  
Author(s):  
Ladislav Vrsalović ◽  
Ivana Ivanić ◽  
Stjepan Kožuh ◽  
Borut Kosec ◽  
Milan Bizjak ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Photoelectron Spectroscopy ◽  
Manganese Oxides ◽  
Cast Alloy ◽  
Microscopic Analysis ◽  
Corrosion Current ◽  
Open Circuit ◽  
Solution Ph ◽  
Corrosion Properties ◽  
X Ray

AbstractThis paper reports on the influence of heat treatment on the corrosion properties of CuAlMn alloy in 0.1%, 0.9% and 1.5% NaCl solution (pH = 7.4). Heat treatment of alloy samples was performed by samples annealing at 900°C for 30 min. Electrochemical methods of investigations included measuring the open circuit potential (Eoc) and linear and potentiodynamic polarisation. Optical microscopy, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) were used to study the morphology and composition of the corroded surfaces, along with X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Heat-treated samples have slightly more positive values of Eoc, slightly lower values of corrosion current density and higher values of polarisation resistance compared with the as-cast alloy. The microscopic analysis showed the rough surfaces due to corrosion processes. Increasing the electrolyte concentration leads to an increase in alloy surface damage. AFM and SEM examinations showed that the surface was covered with interlaced layers of corrosion products, as well as cracks and ducts formed by their dissolution. EDX and XPS analyses showed that corrosive products consist mainly of aluminium and manganese oxides and chlorides. Annealed CuAlMn alloy samples have significantly lower copper content compared with the as-cast CuAlMn alloy.

Improvement of corrosion resistance of maraging steel manufactured by selective laser melting through Intercritical heat-treatment

CORROSION ◽  
10.5006/3972 ◽  
2022 ◽  
Author(s):  
Hamaid Khan ◽  
Gökhan Özer ◽  
Mustafa Safa Yilmaz ◽  
Gürkan Tarakçı
Keyword(s):  
Heat Treatment ◽  
Corrosion Rate ◽  
Maraging Steel ◽  
Corrosion Current ◽  
Open Circuit ◽  
Reversed Austenite ◽  
Corrosion Properties ◽  
Pitting Potential ◽  
Intercritical Heat Treatment ◽  
The Impact

Existing studies suggest that martensite-to-austenite reversion can increase the overall mechanical strength of maraging steel. Their effect on corrosion properties, however, is unclear. Selective laser melted (SLM) specimens were tempered near austenite finish temperatures to investigate the electrochemical effect of reversed austenite. X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectrometry (EDS) were used to characterize their microstructure. To define and test pitting performance, potentiodynamic polarization and open-circuit potential were performed in a 3.5 wt. % NaCl solution. The reversed austenite precipitated mainly along the martensite lath boundaries during the Intercritical heat treatment at 720°C. The nucleation of reversed austenite is allowed by the local Ni enrichment caused by the dissolution of intermetallic particles. As a result, the tempered 720°C specimens reported a higher pitting potential, lowest corrosion current density, and lowest corrosion rate than the as-printed, aged, and homogenized specimens. No investigations have been performed to date that demonstrate the impact of austenite reversion on the corrosion susceptibility of SLM maraging steel. Other than being nobler, austenite is lighter than martensite due to reduced precipitant density, accounting for fewer galvanic cells and a lower corrosion rate.

Principles of Low-Vacuum SEM

1992 ◽  
Vol 50 (2) ◽  
pp. 1304-1305
Author(s):  
Klaus-Ruediger Peters
Keyword(s):  
New Technologies ◽  
High Vacuum ◽  
Optical Microscope ◽  
Specimen Surface ◽  
Electrical Field ◽  
Gaseous Environment ◽  
New Information ◽  
Gas Molecules ◽  
New Interactions ◽  
Gas Pressures

Only recently it became possible to expand scanning electron microscopy to low vacuum and atmospheric pressure through the introduction of several new technologies. In principle, only the specimen is provided with a controlled gaseous environment while the optical microscope column is kept at high vacuum. In the specimen chamber, the gas can generate new interactions with i) the probe electrons, ii) the specimen surface, and iii) the specimen-specific signal electrons. The results of these interactions yield new information about specimen surfaces not accessible to conventional high vacuum SEM. Several microscope types are available differing from each other by the maximum available gas pressure and the types of signals which can be used for investigation of specimen properties.Electrical non-conductors can be easily imaged despite charge accumulations at and beneath their surface. At high gas pressures between 10-2 and 2 torr, gas molecules are ionized in the electrical field between the specimen surface and the surrounding microscope parts through signal electrons and, to a certain extent, probe electrons. The gas provides a stable ion flux for a surface charge equalization if sufficient gas ions are provided.

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