Effect of Shot Peening on Microstructure and Properties of 34CrMo4 Alloy

2018 ◽  
Vol 934 ◽  
pp. 105-110 ◽  
Author(s):  
Ke Jian Li ◽  
Qiang Zheng ◽  
Yue Lin Qin ◽  
Xiao Wei Liu
Keyword(s):  
Plastic Deformation ◽  
Corrosion Resistance ◽  
Shot Peening ◽  
Electrochemical Impedance ◽  
Corrosion Current ◽  
Optical Microscope ◽  
Microstructure And Properties ◽  
Before And After ◽  
Sever Plastic Deformation ◽  
Evolution Of Microstructure

Plastic deformation can induce surface modification, such as shot peening (SP) on workpiece surface is the hot issue of recent scientific research. SP is the efficient way to improve mechanical behavior of specimens by inducing sever plastic deformation on their surface. Nevertheless, this surface treatment induced complex microstructural evolutions such as grain refinement, will enhance the corrosion resistance of specimens. In this work, the microstructure and properties of 34CrMo4 alloy of before and after SP for 20 min have been investigated. The evolution of microstructure and properties were analyzed from the surface and cross-section. The microstructure morphology at the different depth was determined by optical microscope. The results show grain size is increasing with the depth, and the microhardness and compressive residual stress decrease gradually. In terms of corrosion resistance, the 50 μm depth specimen has the best property than other depth, which the potential and corrosion current density are-0.484 V and-5.72 Acm-2, respectively. The maximum polarization resistance is 2055 Ωcm2by capacitive arc radius of electrochemical impedance spectroscopy.

Role of Aluminium on the Microstructure and Corrosion Behaviour of Magnesium Prepared by Powder Metallurgy Method

2020 ◽  
Vol 17 (3) ◽  
pp. 8206-8213
Author(s):  
J. Alias
Keyword(s):  
Corrosion Resistance ◽  
Powder Metallurgy ◽  
Corrosion Behaviour ◽  
Corrosion Current ◽  
Optical Microscope ◽  
High Reactivity ◽  
Aluminium Content ◽  
Powder Metallurgy Method ◽  
X Ray Diffraction ◽  
Promising Development

Much research on magnesium (Mg) emphasises creating good corrosion resistance of magnesium, due to its high reactivity in most environments. In this study, powder metallurgy (PM) technique is used to produce Mg samples with a variation of aluminium (Al) composition. The effect of aluminium composition on the microstructure development, including the phase analysis was characterised by optical microscope (OM), scanning electron microscopy (SEM) and x-ray diffraction (XRD). The mechanical property of Mg sample was performed through Vickers microhardness. The results showed that the addition of aluminium in the synthesised Mg sample formed distribution of Al-rich phases of Mg17Al12, with 50 wt.% of aluminium content in the Mg sample exhibited larger fraction and distribution of Al-rich phases as compared to the 20 wt.% and 10 wt.% of aluminium content. The microhardness values were also increased at 20 wt.% and 50 wt.% of aluminium content, comparable to the standard microhardness value of the annealed Mg. A similar trend in corrosion resistance of the Mg immersed in 3.5 wt.% NaCl solution was observed. The corrosion behaviour was evaluated based on potentiodynamic polarisation behaviour. The corrosion current density, icorr, is observed to decrease with the increase of Al composition in the Mg sample, corresponding to the increase in corrosion resistance due to the formation of aluminium oxide layer on the Al-rich surface that acted as the corrosion barrier. Overall, the inclusion of aluminium in this study demonstrates the promising development of high corrosion resistant Mg alloys.

Effect of pH of coating solution on the adhesion strength and corrosion resistance of hydroxyapatite and octacalcium phosphate coated WE43 alloy

2021 ◽  
pp. 088532822110125
Author(s):  
Tuyet Thi Anh Ngo ◽  
Sachiko Hiromoto ◽  
Linh Chi Do ◽  
Hanh Hong Pham ◽  
Le Hanh
Keyword(s):  
Corrosion Resistance ◽  
Adhesion Strength ◽  
Corrosion Current ◽  
Xrd Analysis ◽  
Octacalcium Phosphate ◽  
Solution Deposition ◽  
Chemical Solution Deposition Method ◽  
Before And After ◽  
Coating Layers ◽  
We43 Alloy

Hydroxyapatite (HAp) and octacalcium phosphate (OCP) layers were formed on Mg- 4mass% Y- 3mass% rare earth (WE43) alloy by a chemical solution deposition method at various pH values of pH 5.5, 6.2, 7.5, and 8.6. Adhesion strength of HAp and OCP layers was evaluated before and after immersing in a medium for 14 days by a pull-off test. The corrosion resistance of these coatings was measured by polarization tests performed in a simulated body fluid (SBF). XRD analysis demonstrated that HAp coating layers were formed at pH 7.5 and 8.6, while OCP coating layers were formed at pH 5.5 and 6.2. Adhesion test results showed that the as-coated pH7.5-HAp layer had the highest adhesion strength of 8.6 MPa, which was attributed to the very dense structure of the coating layer. The as-coated pH8.6-HAp layer showed the adhesion strength of 6.5 MPa. The adhesion strength of the as-coated pH5.5- and pH6.2-OCP layers was 3.9 and 7.1 MPa, respectively, that was governed by the thick and fragile property of the layers. After immersing in the medium for 14 days, the adhesion strength of pH7.5- and pH8.6-specimens decreased to 5.8 and 5.6 MPa, respectively. The pitting corrosion and formation of Mg(OH)2 under the HAp layers were responsible for the decrease of adhesion strength. The polarization tests in SBF at 37 °C showed that the corrosion current density decreased with the HAp and OCP coatings, indicating the improvement of the corrosion resistance of WE43 alloy. The HAp coatings improved the corrosion resistance more efficiently than the OCP coatings.

Effects of potassium silicate on corrosion behavior of dacromet coating

2019 ◽  
Vol 66 (6) ◽  
pp. 819-826
Author(s):  
Khashayar Tabi ◽  
Mansour Farzam ◽  
Davood Zaarei
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Automobile Industry ◽  
Electrochemical Impedance ◽  
Salt Spray ◽  
Corrosion Current ◽  
Potassium Silicate ◽  
Coated Steel ◽  
Content Type ◽  
New Information

Purpose Potassium silicate sealer was applied on solvent-cleaned, acid-pickled, dacromet-coated steel to improve its corrosion resistance. The purpose of this paper is to study the corrosion behavior of dacromet-coated steel. Design/methodology/approach Potassium silicate sealer was applied on solvent-cleaned, acid-pickled, dacromet-coated steel to improve its corrosion resistance. Electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and salt spray were carried out. SEM was used to study the morphological appearance of the surface. Findings The EIS behavior indicated that solvent-cleaned dacromet-coated steel sealed with potassium silicate showed that the corrosion current density was 2.664E − 5 A.cm2 which was reduced to 8.752E − 6 A.cm2 and the corrosion rate, which was 2.264E − 2 mm.year−1, was reduced to 7.438E − 3 mm.year−1 in NaCl 3.5 wt.per cent. EIS was used in NaCl 3.5 wt.%, and the Bode plot characteristics showed that the corrosion protection of solvent-cleaned, dacromet-coated steel was enhanced when sealed with potassium silicate. The EDS results of salt-sprayed, solvent-cleaned samples after 10 days indicated that the main corrosion products are composed of SiO2, ZnO and Al2O3. Research limitations/implications The detection of Li element in EDS was not possible because of the device limitation. Originality/value The current paper provides new information about the sealing properties of potassium silicate and its effects on the corrosion resistance of dacromet coating, which is widely used in many industries such as the automobile industry.

The passive properties of TA10 in Coca-Cola containing oral environment

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ming Liu ◽  
Jun Li ◽  
Danping Li ◽  
Lierui Zheng
Keyword(s):  
Corrosion Resistance ◽  
Passive Film ◽  
Photoelectron Spectroscopy ◽  
Electrochemical Impedance ◽  
Artificial Saliva ◽  
Corrosion Current ◽  
Content Type ◽  
Passive Behavior ◽  
Tooth Demineralization ◽  
Oral Environment

Purpose At present, carbonated drinks such as cola are especially favored by the younger generation. But because of its acid, it often leads to tooth demineralization, resulting in “cola tooth”. However, the influence of cola on the corrosion resistance of passive film of TiA10 alloy restorative materials is rarely reported. The purpose of this study was to analysis the corrosion resistance, composition of the passive film of TA10 alloy in different concentrations of Cola. Design/methodology/approach The passive behavior of TA10 alloy in artificial saliva (AS) and Cola was studied by means of potentiodynamic polarization, electrochemical impedance spectroscopy, cyclic voltammetry, Mott-Schottky techniques and combined with X-ray photoelectron spectroscopy and Auger electron spectroscopy (AES) surface analysis. Findings With the increase of cola content, the self-corrosion current density of the alloy increases sharply, and the corrosion resistance of the passive film is the best in AS, while Rp in cola is reduced to half of that in AS. The thickness of the passive film in AS, AS +cola and cola is about 9.5 nm, 7.5 nm and 6 nm, respectively. The passive film in cola has more defects and the carrier density is 1.55 times as high as that in AS. Cola can weaken the formation process of the protected oxide, promote the formation of high valence Ti-oxides and increase the content of Mo-oxides in the passive film. Originality/value These results have important guiding significance for the safe use of the alloy in the complex oral environments.

Corrosion resistance and characterization studies of calcium series chemical conversion film via green pretreatment on magnesium alloy

2016 ◽  
Vol 63 (6) ◽  
pp. 508-512
Author(s):  
Fengjing Wu ◽  
Xiaojuan Liu ◽  
Xin Xiao
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Electrochemical Impedance ◽  
Chemical Conversion ◽  
Corrosion Current ◽  
Organic Coating ◽  
Hazardous Substances ◽  
Surface Pretreatment ◽  
Content Type ◽  
Az80 Magnesium Alloy

Purpose Magnesium alloys, although valuable, are reactive and require protection before its application in many fields. The purpose of this study was to evaluate a novel anticorrosive chemical conversion film on AZ80 magnesium alloy by environmental-friendly calcium series surface pretreatment. Design/methodology/approach The corrosion resistance of the film was evaluated by potentiodynamic polarization and electrochemical impedance spectroscopy in 3.5 Wt.% NaCl solution. The surface morphologies, microstructure and composition of the film were investigated by scanning electron microscopy and energy-dispersive spectroscopy. Findings The corrosion current density of the calcium series film decreased by more than one order of magnitude as compared to that of the AZ80 magnesium alloy. The conversion film presented dry-mud morphology, and its thickness was estimated to be approximately 4 μm. The conversion film was highly hydrophilic, and the organic coating adhesion on treated AZ80 surface was approximately 13.5 MPa. Originality/value Excellent performance of the calcium-based chemical conversion film on Mg alloy was obtained, which does not contain heavy metals or fluorides and completely conforms to European RoHS (Restriction of Hazardous Substances) standard.

Study of Microstructure and Corrosion Resistance of Zinc Electrodeposits before and after Black Chromating

2017 ◽  
Vol 751 ◽  
pp. 119-124
Author(s):  
Kanokwan Saengkiettiyut ◽  
Pranee Rattanawaleedirojn ◽  
Adisak Thueploy ◽  
Jumpot Wanichsampan ◽  
Yuttanant Boonyongmaneerat
Keyword(s):  
Corrosion Resistance ◽  
Electrochemical Impedance ◽  
Salt Spray ◽  
Alkaline Electrolyte ◽  
Corrosion Properties ◽  
Electrochemical Testing ◽  
Before And After ◽  
Coat Layer ◽  
Zinc Coatings ◽  
Salt Spray Testing

In this work, microstructure and corrosion properties of zinc electroplated steel before and after black chromating was investigated. The test samples were prepared by electrodeposition process, using a commercially-available alkaline electrolyte. Subsequently, the galvanized samples were applied with a black chromate-based passivation layer and a clear top-coat layer. Their microstructures were examined using X-ray diffractometry and scanning electron microscopy. The corrosion resistance of the samples was assessed with the salt spray test, following the ASTM B117, electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization in 5 wt.% NaCl solutions. The study showed that zinc electroplated steels exhibit (110) crystallographic orientation. The passivation and top-coat layers did not affect the microstructure of the zinc layer, and covered uniformly on the zinc layer for all sets of samples. The corrosion resistant results obtained from salt spray testing and electrochemical testing revealed that the microstructure of zinc coatings prepared by using different applied current did not influence on their corrosion resistance markedly. While black passivation followed by top coating provided a significant improvement on corrosion resistance of the coatings.

Corrosion Behavior of Zr53.5Cu26.5Ni5Al12Ag3 Bulk Amorphous Alloy in 3.5% NaCl Solution

2011 ◽  
Vol 299-300 ◽  
pp. 427-431
Author(s):  
Yun Li ◽  
Shi Zhi Shang ◽  
Ming Cheng ◽  
Liang Xu ◽  
Shi Hong Zhang
Keyword(s):  
Corrosion Resistance ◽  
Amorphous Alloy ◽  
Passive Film ◽  
Corrosion Behavior ◽  
Electrochemical Impedance ◽  
Corrosion Current ◽  
Bulk Amorphous Alloy ◽  
Nacl Solution ◽  
Current Densities ◽  
Resistance Decrease

The corrosion behavior of Zr53.5Cu26.5Ni5Al12Ag3 bulk amorphous alloy in 3.5% NaCl solution was investigated by using potentiodynamic polarization experiments and electrochemical impedance spectroscopy (EIS). The results show that Zr53.5Cu26.5Ni5Al12Ag3 bulk amorphous alloy has the better corrosion resistance than its corresponding crystal alloy. During the bath in the 3.5% NaCl solution at 25°C, Zr53.5Cu26.5Ni5Al12Ag3 alloy has the lower corrosion current density than the corresponding crystal alloy. After 100h, the corrosion current densities of Zr53.5Cu26.5Ni5Al12Ag3 and the corresponding crystal alloy are 3.8415×10-8A/cm2 and 5.2827×10-7A/cm2, respectively. The results of EIS test indicate that Zr53.5Cu26.5Ni5Al12Ag3 bulk amorphous alloy has the excellent corrosion resistance because passive film with stable structure formed on the surface in 3.5% NaCl solution. With an increase in the immersion time, the passive film becomes thicker. It leads to impedance resistance and corrosion resistance decrease. The surface of Zr53.5Cu26.5Ni5Al12Ag3 bulk amorphous alloy in 3.5% NaCl solution for 100h was analyzed by SEM and EDS. The results show that the corrosive pitting can be found at both the amorphous alloy and the corresponding crystal alloy. However, the amorphous alloy has the better corrosive pitting resistance than the crystal one because the corrosion products formed by selective dissolving of Zr and Al elements. Moreover, the addition of Ag element helps to improve the corrosion resistance of the amorphous alloy greatly.

An Effective Method to Fabricate 5083 Aluminum Alloy with Excellent Corrosion Resistance

2017 ◽  
Vol 898 ◽  
pp. 1300-1304
Author(s):  
Peng Fei Wang ◽  
Chen Bin Liu ◽  
Jin Chuan Jie ◽  
Ting Ju Li
Keyword(s):  
Aluminum Alloy ◽  
Aluminum Alloys ◽  
Corrosion Behavior ◽  
Corrosion Current ◽  
Optical Microscope ◽  
Electrochemical Test ◽  
Cryogenic Rolling ◽  
Before And After ◽  
Room Temperature Rolling ◽  
5083 Aluminum Alloy

The 5083 aluminum alloy was prepared and subjected to cryogenic rolling (CR) after heat treatment. The samples were reduced from 15mm to 1.5 mm in the thickness direction and the amount of deformation was 90%. For comparison, samples with the same deformation amount were obtained by room temperature rolling (RTR). The corrosion behavior of CR and RTR samples was measured by electrochemical test, and their microstructures before and after corrosion had been studied through electron scanning microscopy (SEM) and optical microscope (OM). The influence of cryogenic rolling on the corrosion behavior of 5083 aluminum alloys was explored. The experiment results suggested that anti-corrosion ability of 5083 aluminum alloys could be enhanced through cryogenic rolling. The corrosion potential elevated and the corrosion current density reduced according to the electrochemical test. The primary reasons and corresponding mechanism were also discussed.

Alumina Sol-Gel Films and Alodine Films on Al 2024 Alloy

2011 ◽  
Vol 356-360 ◽  
pp. 364-367
Author(s):  
Qi Zhou ◽  
Xuan Xiao ◽  
Da Li Zhao ◽  
En Jun Song
Keyword(s):  
Corrosion Resistance ◽  
Aluminium Alloy ◽  
Electrochemical Impedance ◽  
Sol Gel ◽  
Film Surface ◽  
Corrosion Current ◽  
Promising Alternative ◽  
Gel Film ◽  
Alumina Sol ◽  
Sol Gel Films

Development of the sol-gel films for painting pretreatment of aluminium alloy is to replace bichromate conversion films such as Alodine. Corrosion resistance of Alodine film and sol-gel film were evaluated through potentiodynamic polarization curves, electrochemical impedance spectroscopy, salt spraying and acidic dropping solution. Sol-gel film is almost the same as Alodine film at the film surface density, salt spraying resistance and adhesion with painting coating. Changing color times of dropping solution on sol-gel film is shorter than Alodine film. But the corrosion current of sol-gel film is lower than Alodine and the impedance value is higher than Alodine in 35g/L NaCl solution. Mechanism of corrosion resistance of alumina sol-gel film is that the cathode reaction and anodic reactions are restrained by sol-gel film in the Cl- corrosive medium. The EIS of sol-gel film consisted of only a single capacitive arc with one time constant. Sol-gel coating can prevent or delay the corrosive solution from infiltrating the substrate for its better isolation function, thus protecting 2024 aluminium alloy from corrosion. Sol-gel films can improve corrosion resistance of aluminum alloy and have the same adhesion as Alodine film. It will be a promising alternative pretreatment for aluminum alloys prior to painting.

scholarly journals Cr3C2-NiCr Coating for the Protection of API Steel Corrosion in Concentrated Sodium Chloride Solution

Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 249
Author(s):  
El-Sayed M. Sherif ◽  
Magdy M. El Rayes ◽  
Hany S. Abdo
Keyword(s):  
Corrosion Resistance ◽  
Sodium Chloride ◽  
Corrosion Rate ◽  
Electrochemical Impedance ◽  
Pipeline Steel ◽  
Protective Layer ◽  
Steel Corrosion ◽  
Corrosion Current ◽  
Cyclic Polarization ◽  
Current Time

In the present work, a layer of 75%Cr3C2−25%NiCr with thickness of 260 ± 15 µm was coated onto the API-2H pipeline steel surface using high-velocity oxy-fuel deposition. The effect of 75%Cr3C2−25%NiCr coating on the corrosion of the API steel after 1 h, 24 h, and 48 h exposure in 4.0% sodium chloride solutions is reported. The corrosion tests were performed using potentiodynamic cyclic polarization, electrochemical impedance spectroscopy, and chronoamperometric current–time techniques along with scanning electron microscopy and energy-dispersive X-ray analyses. The curves of polarization indicated that the presence of the coating increases the corrosion resistance of the steel through decreasing its corrosion current and corrosion rate. Impedance data showed that all resistances recorded higher values for the coated API steel. Chronoamperometric current–time measurements confirmed that the coated API steel has lower absolute current values and thus lower corrosion rate. All results proved that the presence of 75%Cr3C2−25%NiCr coating enhances the corrosion resistance of the API steel via the formation of a protective layer of Cr and Ni oxides, which could lead to decreasing the corrosion rate.

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