Corrosion evaluation of Ti-6Al-4V parts produced with electron beam melting machine

2016 ◽  
Vol 22 (2) ◽  
pp. 322-329 ◽  
Author(s):  
Dana H. Abdeen ◽  
Bruce R. Palmer
Keyword(s):  
Electron Beam ◽  
Corrosion Behavior ◽  
Pitting Corrosion ◽  
Electron Beam Melting ◽  
Saturated Calomel Electrode ◽  
Nacl Solution ◽  
Pitting Potential ◽  
Exterior Surface ◽  
Content Type ◽  
Critical Pitting Temperature

Purpose This paper aims to evaluate the corrosion behavior of Ti-6Al-4V parts produced with electron beam melting (EBM) machine and compare it with wrought Ti-6Al-4V alloy. Design/methodology/approach Potentiodynamic and potentiostatic tests were applied on EBM Ti-6Al-4V in 3.5 per cent mass NaCl solution to determine the pitting potential and critical pitting temperature (CPT). A relation between pitting potential and temperature was established for EBM Ti-6Al-4V alloy by conducting potentiodynamic testing under different temperatures. CPT was also measured for EBM Ti-6Al-4V alloy in 3.5 per cent mass NaCl solution at a standard potential of 800 mV vs saturated calomel electrode (SCE). The same tests were performed on wrought Ti-6Al-4V for comparison purposes. Moreover, CPT for EBM Ti-6Al-4V alloy was measured in 3.5 per cent mass NaCl solution of different pH of 2.0, 5.7 and 10.0 to examine the effect of aggressive conditions on the pitting corrosion of EBM alloy. Findings Potentiodynamic test resulted in a relatively high pitting potential of EBM alloy, which was close to the pitting potential of wrought alloy even at higher temperatures. In addition, EBM samples did not pit when potentiostatic test was performed at 800 mV vs SCE, even at high and low values of pH. Originality/value EBM Ti-6Al-4V alloy has been increasingly playing an important role in aerospace, automobile and industrial fields. The technique and conditions of manufacturing form voids and increase roughness of the exterior surface of EBM objects, which might increase the tendency to initiate pitting corrosion within its holes and surface folds. This article shows that, despite surface variations and porosity in EBM Ti-6Al-4V alloy, the material maintained its corrosion resistance. It was found that the corrosion behavior of EBM alloy was close to that of the conventionally made wrought Ti-6Al-4V alloy.

Effect of processing parameters of electron beam melting machine on properties of Ti-6Al-4V parts

2016 ◽  
Vol 22 (3) ◽  
pp. 609-620 ◽  
Author(s):  
Dana H. Abdeen ◽  
Bruce R. Palmer
Keyword(s):  
Surface Roughness ◽  
Electron Beam ◽  
Process Parameters ◽  
Electron Beam Melting ◽  
Processing Parameters ◽  
Beam Current ◽  
Exterior Surface ◽  
Content Type ◽  
Critical Pitting Temperature ◽  
Model Equations

Purpose This paper aims to study the effect of processing parameters of an electron beam melting (EBM) machine on the surface roughness, critical pitting temperature and density of Ti-6Al-4V parts produced from the EBM machine. Design/methodology/approach In this study, statistically designed experiments were used to manufacture Ti-6Al-4V samples in the EBM machine under different process parameters of beam current, beam speed and offset focus. Surface roughness was measured for as-built samples using a 3D profilometer. Then, a potentiostatic test was conducted under 2.40 V vs saturated calomel electrode to determine the critical pitting temperature (CPT) in 3.5 per cent mass NaCl solution for the samples of different processing parameters. Next, density was measured for these samples. Finally, model equations were established to relate EBM’s process parameters to measured properties of surface roughness, CPT and density. Findings Results showed that offset focus had the main influence on surface roughness more than the beam current and the beam speed. Changing processing parameters did not affect corrosion behavior of EBM Ti-6Al-4V as CPT did not vary widely, although a slight effect on CPT values obtained from the beam current and the beam speed. Density was greatly affected by the offset focus more than the other parameters. It can be concluded that uniform and precise measurements of roughness and density are not achievable through this machine; only a range of these properties can be attained. Originality/value EBM machine produces 3D parts in a layer-based building process under high temperature and vacuum atmosphere. Due to the manufacturing technique and conditions, the resulting object has irregularities on the exterior surface and voids that are formed within the part, both of which affect samples’ properties like surface roughness, CPT and density. This study established model equations that can relate parts’ properties to processing parameters so that parts of specific properties are obtained to fit the application they are used for. For each property, ANOVA fits vs linear energy were also obtained.

The effect of EBM process parameters upon surface roughness

2016 ◽  
Vol 22 (3) ◽  
pp. 495-503 ◽  
Author(s):  
Rebecca Klingvall Ek ◽  
Lars-Erik Rännar ◽  
Mikael Bäckstöm ◽  
Peter Carlsson
Keyword(s):  
Surface Roughness ◽  
Electron Beam ◽  
Surface Properties ◽  
Process Parameters ◽  
Electron Beam Melting ◽  
Design Methodology ◽  
New Materials ◽  
Content Type ◽  
Melt Pool ◽  
Practical Implications

Purpose The surface roughness of products manufactured using the additive manufacturing (AM) technology of electron beam melting (EBM) has a special characteristic. Different product applications can demand rougher or finer surface structure, so the purpose of this study is to investigate the process parameters of EBM to find out how they affect surface roughness. Design/methodology/approach EBM uses metal powder to manufacture metal parts. A design of experiment plan was used to describe the effects of the process parameters on the average surface roughness of vertical surfaces. Findings The most important electron beam setting for surface roughness, according to this study, is a combination of “speed and current” in the contours. The second most important parameter is “contour offset”. The interaction between the “number of contours” and “contour offset” also appears to be important, as it shows a much higher probability of being active than any other interaction. The results show that the “line offset” is not important when using contours. Research limitations/implications This study examined “contour offset”, “number of contours”, “speed in combination with current” and “line offset”, which are process parameters controlling the electron beam. Practical implications The surface properties could have an impact on the product’s performance. A reduction in surface processing will not only save time and money but also reduce the environmental impact. Originality/value Surface properties are important for many products. New themes containing process parameters have to be developed when introducing new materials to EBM manufacturing. During this process, it is very important to understand how the electron beam affects the melt pool.

Processing windows for Ti-6Al-4V fabricated by selective electron beam melting with improved beam focus and different scan line spacings

2019 ◽  
Vol 25 (4) ◽  
pp. 665-671 ◽  
Author(s):  
Christoph R. Pobel ◽  
Fuad Osmanlic ◽  
Matthias A. Lodes ◽  
Sebastian Wachter ◽  
Carolin Körner
Keyword(s):  
Electron Beam ◽  
Electron Beam Melting ◽  
High Energy ◽  
Beam Deflection ◽  
Content Type ◽  
Powder Bed ◽  
Manufacturing Method ◽  
High Speeds ◽  
Selective Electron Beam Melting ◽  
Scan Line

Purpose Selective electron beam melting (SEBM) is a highly versatile powder bed fusion additive manufacturing method. SEBM is characterized by high energy densities which can be applied with nearly inertia free beam deflection at high speeds (<8.000 m/s). This paper aims to determine processing maps for Ti-6Al-4V on an Arcam Q10 machine with LaB6 cathode design. Design/methodology/approach Scan line spacings of 100, 50 and 20 µm in a broad parameter range, focusing on high deflection and build speeds are investigated. Findings There are broad processing windows for dense parts without surface flaws for all scan line spacings which are defined by the total energy input and the area melting velocity. Originality/value The differences and limitations are discussed taking into account the beam properties at high beam energy and velocity as well as evaporation related loss of alloying components.

Effects of Retrogression Treatment Process on the Mechanical Properties and Corrosion Behavior of the Graphene/7075 Aluminum Matrix Composite

2020 ◽  
Vol 993 ◽  
pp. 747-755
Author(s):  
Bing Hui Ren ◽  
Kang Wang ◽  
Ran Wang ◽  
Jin Feng Leng
Keyword(s):  
Electrical Conductivity ◽  
Corrosion Behavior ◽  
Matrix Composite ◽  
Pitting Corrosion ◽  
Aluminum Matrix ◽  
Corrosion Current ◽  
Aluminum Matrix Composite ◽  
Pitting Potential ◽  
Time To Peak ◽  
Peak Aging

The influence of various retrogression and re-ageing (RRA) treatment processes on the hardness, electrical conductivity and corrosion behavior of graphene/7075 aluminum matrix composite were investigated. The results showed that the hardness decreased swiftly at the initial stage and short time to peak value as the retrogression temperature (170 °C, 180 °C, 190 °C, 200 °C) rises. In the RRA 180 °C/120 min process, the electrical conductivity and peak-aging Brinell hardness were 37.9%IACS, 192.8. This RRA treatment possessed excellent pitting corrosion resistance, and the corresponding pitting potential (Epit), the passivation potential (Epit-Ecorr), the pitting corrosion current density (Logicorr) were -0.756V, 0.558V, -1.836A/cm2, respectively. This enhance can attribute that the continuous η phase distributed along the grain boundary became intermittent and coarse in the retrogression stage.

Effect of Passivation on Pitting Corrosion of 316L Stainless Steel in Concentrated Seawater

2012 ◽  
Vol 472-475 ◽  
pp. 127-131
Author(s):  
Feng Jun Lang ◽  
Ying Ma ◽  
Jian Rong Liu ◽  
Xian Qiu Huang ◽  
Mou Cheng Li
Keyword(s):  
Stainless Steel ◽  
Pitting Corrosion ◽  
Anodic Polarization ◽  
316L Stainless Steel ◽  
Pitting Potential ◽  
Critical Pitting Temperature

The influence of passivation on pitting corrosion of 316L stainless steel in concentrated seawater was investigated by using cyclic anodic polarization and critical pitting temperature. The results indicated that the pitting potential of passivated specimen was higher than that of matrix specimen in concentrated seawater at 25°C and 85°C. Critical pitting temperature value of passivated specimen was 56°C, which was much higher than 11°C for matrix specimen. Pitting corrosion occurred in the formed pit of passivated specimen, and metastable pit, lacy cover and new pit were observed in pit morphology.

Electrochemical Testing for Pitting Corrosion Above Ambient Temperatures Using the Syringe Cell

CORROSION ◽  
10.5006/3854 ◽  
2021 ◽  
Author(s):  
Anup Panindre ◽  
Gerald Frankel
Keyword(s):  
Pitting Corrosion ◽  
Specimen Surface ◽  
Hot Plate ◽  
Pitting Potential ◽  
Ambient Temperatures ◽  
Electrochemical Testing ◽  
Different Temperatures ◽  
Critical Pitting Temperature ◽  
Constant Potential ◽  
Passive Alloys

The syringe cell method has been further developed to evaluate the temperature dependence of pitting corrosion in passive alloys having critical pitting temperature above ambient without artifacts associated with crevice corrosion. The pitting potential of commercially available duplex stainless steel type 2205 was measured at different temperatures by using a hot plate to heat the specimen. Breakdown potentials decreased by about 1 V at test temperatures above 50 °C. The critical pitting temperature (CPT) of the alloy was determined to be between 54 °C and 59 °C by scanning the temperature of the specimen surface during a constant potential hold. In all experiments, pits were observed in the area defined by the electrolyte droplet in contact with the specimen surface. The CPT of the alloy determined using a more conventional approach mentioned in ASTM Standard G48 Method C was 55 °C.

Effect of carbides on sensitivity of pitting corrosion in Inconel 718 alloy

2020 ◽  
Vol 67 (2) ◽  
pp. 158-165
Author(s):  
Xianping Wei ◽  
Wen Jie Zheng
Keyword(s):  
Pitting Corrosion ◽  
Inconel 718 ◽  
Design Methodology ◽  
Electrochemical Impedance ◽  
Immersion Test ◽  
Nacl Solution ◽  
Inconel 718 Alloy ◽  
Content Type ◽  
Corrosion Susceptibility ◽  
Dynamic Electrochemical Impedance Spectroscopy

Purpose This paper aims to expand the application area of Inconel 718 alloy in marine environment, the sensitivity of pitting corrosion should be analyzed and discussed, especially the effect of block carbides. Design/methodology/approach Effect of carbides on the sensitivity of pitting corrosion for Inconel 718 alloy was carried out at 30°C in 3.5% NaCl solution using dynamic electrochemical impedance spectroscopy and anodic polarization techniques. In addition, the initiation of pitting corrosion was investigated by immersion test in 0.05 M HCl + 6% FeCl3 solution. Findings As a result, the precipitation of carbides, as the initiation of pitting corrosion, increased pitting corrosion susceptibility, especially the block carbides could lead to deep-spalling. Within that process, temperature and potential acted as the main controlling factors, and the effect of the latter was more distinct. Originality/value The initiation of pitting corrosion was revealed by the immersion test. The mechanism of pitting corrosion was analyzed and discussed.

The corrosion behavior of chromated AA2024 aluminum alloy in 3.5% NaCl solution

2019 ◽  
Vol 66 (6) ◽  
pp. 879-887 ◽  
Author(s):  
Yong Zhou ◽  
Pei Zhang ◽  
Jinping Xiong ◽  
Fuan Yan
Keyword(s):  
Aluminum Alloy ◽  
Grain Boundary ◽  
Corrosion Behavior ◽  
Electrochemical Measurement ◽  
Nacl Solution ◽  
Content Type ◽  
Chromate Conversion Coating ◽  
Chromate Coating ◽  
Corrosion Mechanisms ◽  
Corrosion Pits

Purpose A chromate conversion coating was prepared on the surface of bare AA2024 aluminum alloy by direct immersion in the chromating treatment bath, and the corrosion behavior of chromated AA2024 aluminum alloy in 3.5 per cent NaCl solution was studied by electrochemical measurement and microstructural observation. Design/methodology/approach According to the polarization curve test and the scanning electron microscope observation, the corrosion evolution of chromated AA2024 in 3.5 per cent NaCl solution was divided into the following three stages: coating failure, pitting corrosion and intergranular corrosion (IGC). Findings In the first stage, the chromate coating degraded gradually due to the combined action of chloride anions and water molecules, resulting in the complete exposure of AA2024 substrate to 3.5 per cent NaCl solution. Subsequently, in the second stage, chloride anions adsorbed at the sites of θ phase (Al2Cu) and S phase (Al2CuMg) on the AA2024 surface preferentially, and some corrosion pits initiated at the above two sites and propagated towards the deep of crystal grains. However, the propagation of a pit terminated when the pit front arrived at the adjacent grain boundary, where the initiation of IGC occurred. Originality/value Finally, in the third stage, the corrosion proceeded along the continuous grain boundary net and penetrated the internal of AA2024 substrate, resulting in the propagation of IGC. The related corrosion mechanisms for the bare and the chromated AA2024 were also discussed.

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