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Unique characteristics such as biocompatibility, degradation capability, and mechanical properties have positioned magnesium alloys as highly favorable choices for use in various medical devices and implants. However, their rapid degradation and associated challenges have limited their widespread use. This study conducts a thorough analysis into the corrosion behavior of magnesium alloys when open to various coatings, using both in vitro and in vivo environments. The review focuses on understanding the degradation mechanisms, factors influencing corrosion, and the resulting consequences. Additionally, it explores the composition of coatings and metals as effective means to control degradation, along with surface treatment and corrosion management methods. To enhance the degrading behavior, bioactivity, and biocompatibility of magnesium alloys, a multistep approach involving coating techniques such as HA coating, LDH, CaP, and titanium dioxide coating is recommended. These coatings have shown significant potential in improving the exterior properties of Mg alloys. Furthermore, using multifunctional coatings is extremely effective in creating secure and bioactive substrates for the application of biodegradable implants, demonstrating significant potential in the field of biomedical engineering. [ABSTRACT FROM AUTHOR]

Biodegradable suture anchors based on Mg-Nd-Zn-Zr alloy were developed for ligament-to-bone fixation in rotator cuff surgeries. The Mg alloy anchors were designed with structural features of narrow tooth and wide tooth, and simulated through finite element analysis (FEA). Meanwhile, the corrosion behaviors of the Mg alloy anchors were studied by immersion test and the mechanical properties were investigated by measuring the maximum torque and pull-out force. The simulation result showed that the wide-tooth anchor exhibited more a uniform stress distribution and lower shear stress in the torsion process, suggesting a satisfactory torsional resistance of this structure. Meanwhile, the wide-tooth anchor exhibited a lower Von-Mises stress after applying the same pull-out force in the simulation, indicating a higher resistance to pull-out failure of the anchor. The result of the immersion test indicated that the wide-tooth anchor exhibited a slightly slower corrosion rate in Hank's solution after 14-day immersion, which was beneficial to enhance the structural and mechanical stability of the biodegradable suture anchor. Furthermore, the results of the mechanical properties test demonstrated that the wide-tooth anchor showed superior performance with higher maximum torques and axial pull-out forces before and after corrosion. More importantly, the axial pull-out force and maximum torque for the wide-tooth anchor decreased by 5.86% and 8.64% after corrosion, which were significantly less than those for the narrow-tooth anchor. Therefore, the wide-tooth suture anchor with lower corrosion rate, higher mechanical properties and structural stability is a promising candidate for ligament-bone fixation in the repair of rotator cuff injuries. [ABSTRACT FROM AUTHOR]

In this work, Fe-20Cr-20Mn-0.75N (wt.%) high-nitrogen stainless steel (HNSS) was studied using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and electrochemical testing. The corrosion behaviors of Fe-20Cr-20Mn-0.75N HNSS with different concentrations of NaCl were studied. The composition of a passive film on Fe-20Cr-20Mn-0.75N HNSS was analyzed using X-ray photoelectron spectroscopy (XPS) at an applied potential of 0.2VSCE. The results showed that, with the increase in Cl− concentration, the corrosion tendency and corrosion rate of Fe-20Cr-20Mn-0.75N HNSS get higher. In the solution of a low Cl− concentration, the fraction of Fe and Cr oxides in the passive film is higher, and the passive film is thicker and more stable. By increasing the stability of the passive film and preventing its rupture, the elevated NH4+ concentration can enhance the corrosion resistance of Fe-20Cr-20Mn-0.75N HNSS in a NaCl solution. [ABSTRACT FROM AUTHOR]

Aluminum‐based glassy alloys and composites exhibit more than two times higher tensile and compressive strength and superior corrosion resistance compared to the conventional Al alloys. However, the low glass‐forming ability (GFA) of Al‐based glass‐forming compositions restricts the synthesis of large dimension Al‐based amorphous alloys. In contrast, powder metallurgy route leads to synthesis of higher‐dimension Al‐based metallic glasses and composites. A detailed review on the efforts made to improve the dimension and mechanical properties of the Al‐based glassy alloys and composites is essential to further develop these materials for industrial applications. Researchers aspiring to develop high‐strength light‐weight materials can be benefited from such a detailed review on Al‐based amorphous alloys and composites. In this review article, a holistic approach is made to understand the GFA, crystallization behavior, corrosion resistance, and mechanical and electronic properties of Al‐based glassy alloys and composites. The effects of various alloying elements on GFA and criteria to optimize Al‐based glass‐forming alloy composition are discussed. The crystallization behavior is discussed with phase‐separation and quenched‐in nuclei models. The effects of various crystalline phases in the amorphous matrix on corrosion resistance and mechanical and electronic properties are discussed in detail. [ABSTRACT FROM AUTHOR]

Laser cladding is commonly used to improve the wear and corrosion resistance of the substrate material. However, mechanical machining is necessary, because the surface irregularities and poor surface roughness after laser cladding. It is urgent to investigate the effect of machining on the corrosion resistance of the laser cladded layers, so as to avoid the reduction of corrosion resistance due to the use of inappropriate cutting parameters. In the present study, the influence of turning-induced surface roughness on the corrosion resistance from the viewpoint of corrosion potential was analyzed first. The corrosion potential is the result of the effect of roughness height parameters and functional parameters. Second, the effect of the machining and subsequent burnishing on the corrosion resistance was analyzed by comparing the corrosion behaviors of the turned and burnished surfaces. The polarization resistance is critically increased by subsequent burnishing. Third, the sensitivity of the machined surface on corrosion resistance was analyzed by EIS method. The strengthening mechanism of machining and subsequent burnishing on the corrosion resistance was determined. On the basis of this research, it is expected to be used to guide the selection of appropriate feed parameter in prior turning to improve the strengthening effect of subsequent burnishing, and then, to improve the surface integrity and corrosion resistance of the laser cladded layer. [ABSTRACT FROM AUTHOR]

AlCoCrFeNi2.1 eutectic high entropy alloy (EHEA) has attracted significant interest among researchers due to unprecedented mechanical properties compared with single-phase solid solution high entropy alloys; however, the high content of cobalt element limits its engineering applications. In this paper, the mechanical and corrosion behaviors of cost-effective AlCrFeNi3.1 and AlCrFe2Ni2.1 HEAs were systematically studied by tensile tests and electrochemical methods; meanwhile, the results were compared with AlCoCrFeNi2.1 EHEA. The results indicated that all the studied HEAs showed dual phase microstructure composed of FCC and BCC/B2 phases. Due to the hetero-deformation induced strengthening, all the studied HEAs showed an excellent combination of strength and ductility with fracture strength over 1 GPa and fracture strain exceeding 17%, indicating that substituting the cobalt element of AlCoCrFeNi2.1 EHEA by nickel or iron element is feasible from the perspective of mechanical properties. As for the corrosion behaviors in 3.5 wt.% NaCl solution, AlCrFeNi3.1 HEA exhibited the best corrosion resistance due to the high volume fraction of the corrosion resistant FCC phases and low Al/Cr ratio of BCC/B2 phases, while AlCrFe2Ni2.1 HEA showed the worst corrosion resistance owing to the high Al/Cr ratio of BCC/B2 phases. [ABSTRACT FROM AUTHOR]

Herein, fiber laser welding experiments are performed to evaluate the microstructure, mechanical properties, and corrosion behavior of dissimilar/similar joints between DP980 and QP980 steel. Results show that the fusion zone (FZ) of all joints consists of lath martensite with high microhardness (≈480 HV); the retained austenite content in the subcritical heat‐affected zone (HAZ) in the QP980 side of the dissimilar weld joint (WJ) is less than base metals (BMs). Lower hardness in the subcritical HAZ is found compared with BMs in all joints. The microstructure of softening zones is tempered martensite, and the reduction in hardness is about 8.5−10.8% of BMs, which has a great influence on the tensile fracture position of WJs. All joints fracture at softening zones with a typical feature of ductile fracture, and the joint efficiencies are above 96%. The electrochemical corrosion test reveals that the welded samples exhibit a higher corrosion rate compared with the BMs due to the increase in martensite content and area fraction of grain boundary. [ABSTRACT FROM AUTHOR]

The Selective Laser Melting (SLM) is an effective method to produce highly corrosion resistant Oral Alveolar Implants (OAI) by changing the scanning speed. Nevertheless, the long-term corrosion behavior of SLM 316L orthodontic bracket alloys in artificial saliva is overlooked in previous studies. In this study, 316L SS samples fabricated by SLM at different scanning speeds (800 mm/s, 1200 mm/s, and 1600 mm/s) were conducted a long-term (90 days) immersion test by being put into artificial saliva with three different pH values (pH 1.5, pH 4, and pH 6). The morphology, XRD and especially corrosion behavior of the samples fabricated by SLM and forging were investigated. The XRD results exhibit that highspeed scanning accelerates the cooling rate and inhibits the δ → γ phase transformation proceeding. Corrosion results show that the corrosion attack induced by pre-existing pores will expand through the crevices and break down the surface structure around the pores, leading to corrosion damage area to expand to several times of the original pore area. Besides, the mean corrosion rate of the sample at a scanning speed of 800 mm/s shows better corrosion resistance in artificial saliva of pH 4 and pH 6. Compared with wrought 316L SS samples, the SLM 316L SS samples had an obvious difference in the performance of corrosion rate and corrosion behaviors. [ABSTRACT FROM AUTHOR]

Dissoluble magnesium alloys for fabrication of fracturing tools have received increasing attention in recent years. However, most of the existing research is focused on the small-sized samples prepared in the laboratory, and there is almost no report on the industrial dissoluble magnesium alloys. In this study, large-scale Mg-Al-Zn-Mn-Ca-Ni alloys with a diameter of 110 mm were prepared by a semi-continuous casting and two-step extrusion method, and the corresponding microstructure and mechanical and corrosion properties were also investigated. It was found that after two-step extrusion, the mainly precipitate phases in the Mg-Al-Zn-Mn-Ca-Ni alloy are bulk-like AlMnNi, strip-like Al3Ni, and granular-like and lamellar-like Mg17Al12 phases. Due to the combined effects of grain refinement and precipitation strengthening, the Mg-Al-Zn-Mn-Ca-Ni alloy obtained excellent mechanical properties after two-step extrusion, and its ultimate tensile strength, yield strength, and elongation were 314.6 MPa, 191.2 MPa, and 13.1%, respectively. Moreover, the corrosion rate of the alloy in 3 wt.% KCl at 93 °C was as high as 97.61 mg·cm−2·h−1. This work provides a high-performance, low-cost, and large-scale alloy product for the fabrication of dissoluble fracturing tools. [ABSTRACT FROM AUTHOR]

In this paper, Mo-based titanium–zirconium (TZM) alloys containing 0.06, 0.07, 0.08 and 0.09% Zr were produced by mechanical alloying method and the effect of Zr on the microstructure and corrosion behavior of the TZM alloy was studied. Microstructural properties of TZM alloys were characterized by SEM + EDS, XRD analysis and micro hardness tests. In corrosion tests, Tafel extrapolation and Electrochemical Impedance Spectroscopy (EIS) methods were used in solutions with different pH values (pH 4, pH 7 and pH 10). As a result of the studies, it is seen that depending on the amount of Zr added to the TZM alloy, different secondary phases are formed in the microstructure of Mo matrix and the grain boundaries. According to Tafel curves in pH 4, 7 and 10 solutions of TZM alloys with different Zr composition and electrochemical impedance spectroscopy (EIS) results. The highest corrosion resistance (in mm/year) was obtained in 0.09% Zr TZM alloy, the lowest corrosion resistance was obtained in 0.06% Zr TZM alloy. Moreover, the highest corrosion resistance was obtained at pH 7 and the lowest corrosion resistance at pH 10. [ABSTRACT FROM AUTHOR]

Making a tantalum carbide (TaC) coating on Ta substrates is an effective way to improve the mechanical and anti-corrosion properties of Ta. However, conventional methods for making a TaC coating require high-temperature conditions of over 1600 °C to get a TaC thickness of > 20 μm. Herein, a TaC coating of > 20 μm thickness was prepared on a Ta substrate in molten CaCl2-CaC2 at 850 °C for 4 h. In the molten salt electrolyzer, the Ta plate served as the anode where C22− was oxidized and simultaneously reacted with Ta to form a TaC layer, and Ca2+ was reduced and alloyed with C to form CaC2 that can replenish the C22−. The electrolytic TaC exhibited an average hardness of 962 HV that was 6 times of the bare Ta substrate. In the 3.5 wt% NaCl solution, the TaC coating displayed a higher corrosion potential and lower corrosion current density (0.48 V, 1.59 μA cm−2) than Ta substrate (0.35 V, 1.85 μA cm−2) and the mixtures of TaC and Ta2C (0.35 V, 1.78 μA cm−2), indicating its better corrosion resistance. The molten salt anodic carbidation may lead to a general way to prepare transition metal carbide coatings with enhanced carburizing kinetics at < 1000 °C. [ABSTRACT FROM AUTHOR]

The influence of various Ag contents on the microstructure, mechanical properties, and corrosion behavior of extruded Al-4.0Cu-1.1Li-0.4Mg-xAg-0.2Mn-0.2Zr (x = 0.4 and 0.9, wt.%) alloys was investigated. The alloy with 0.9 Ag content contains higher number density of slender T1 (Al2CuLi) precipitates along with some θ' (Al2Cu) phases in the matrix than the alloy with 0.4 Ag content, which is associated with a more rapid hardening response and higher mechanical properties and corrosion resistance, particularly for aging at 130 °C. When aging at high temperatures (above 160 °C), the increase of Ag content mitigates hardness loss by preventing the T1 precipitates from coarsening, and makes the alloy decorate more coarse precipitates at grain boundaries, which leads to the fracture morphology mainly occupied by intergranular fracture. Furthermore, due to the simultaneous promotion of T1 precipitates at grain boundaries and in grain interiors, the 0.9 Ag-containing Al-Cu-Li-Mg-Ag alloy has almost no improvement in corrosion resistance. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Mining & Metallurgy. Section B: Metallurgy is the property of Journal of Mining & Metallurgy and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Selective laser melting (SLM) of biodegradable metallic materials offers a great potential for manufacturing customized implants. Herein, SLM processing of a novel Fe–30Mn–1C–0.02S twinning‐induced plasticity (TWIP) alloy and the resulting structural, mechanical, and corrosion properties are presented. The occurring rapid solidification results in a fine‐grained austenitic microstructure with mainly homogeneous element distribution, which is investigated by scanning electron microscopy (SEM) combined with energy‐dispersive X‐ray spectroscopy (EDX) and electron backscatter diffraction (EBSD) as well as X‐ray diffraction (XRD). By processing the alloy via SLM, significantly higher strengths under tensile and compressive load in comparison with those for the as‐cast counterpart and a 316L reference steel are achieved. Electrochemical corrosion tests in a simulated body fluid (SBF) indicate a moderate corrosion activity, and a beneficial uniform degradation is shown in immersion tests in SBF. Regarding the envisaged application for vascular implants, SLM‐processed stent prototypes out of the novel alloy are presented and a first functionality test is shown. [ABSTRACT FROM AUTHOR]

Cost‐effective macroporous alumina–mullite membrane supports are fabricated by sintering coarse α‐alumina and colloidal silica, using cornstarch as the foaming agent at 1550 °C for 2 h in air atmosphere. To evaluate the corrosion resistance of such membrane supports, the corrosion behaviors of the supports before and after corroding in the H2SO4 and NaOH solutions (80 °C) are systematically investigated. Interestingly, with increasing Al2O3/SiO2 ratio, the support presents numerous alumina grains and little glass phases, resulting in excellent corrosion resistance especially in acidic media. Benefiting from the alumina grains and little glass phases among the grain boundaries, lower mass loss, less variations in pore size and porosity, high residual strength, and an almost unchanged gas flux are obtained for a higher Al2O3/SiO2 ratio support. The porous support, herein, is suitable for microfiltration membranes used in harsh environments. [ABSTRACT FROM AUTHOR]

The electrolytic hydrogen precharging process is used to analyze the influence of hydrogen on the microstructure, corrosion resistance, and mechanical properties of pure titanium. The results demonstrate that two types of titanium hydrides (δ‐TiHx and ϵ‐TiH2) are detected by electron backscatter diffraction (EBSD), and the volume fraction of titanium hydrides, the local strain caused by hydrogen precipitation, and the thickness of hydrides layer increase with the increase in precharging time. It is noteworthy that the formation of hydrides layer has a protective effect on general corrosion, but the local strain caused by hydrides precipitation leads to the destruction of corrosion resistance, as a result the corrosion resistance of pure titanium increases first and then decreases with the increase in hydrogen precharging time. Moreover, with the precipitation of hydrides, the fracture mode changes from ductile failure to duplex‐ and multimode failure, resulting in the decrease in ultimate tensile strength (UTS) and elongation. Therefore, the mechanical and electrochemical properties of the precharged samples first increase and then decrease with the increase in precharging time, reaching their optimum values at 10 h, and the critical precharging time is determined to be 75 h when comparing those properties with pure titanium. [ABSTRACT FROM AUTHOR]

The effect of synergistic reinforcement of two types of carbon nanofillers, carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs), on the corrosion behavior of plasma‐sprayed alumina (Al2O3) nanocomposite coating in 3.5 wt% NaCl solution is studied. Incorporation of 1 wt% CNT and 0.5 wt% GNP into the Al2O3 matrix reduces the corrosion current density of the matrix from 2.78 to 0.21 μA cm−2, which drastically leads to a 13 times reduction in the corrosion rate of the Al2O3 matrix as compared with pure Al2O3 coating. The plausible reasons to this improvement are characterized by the filling of gaps, crevices, and microholes in the Al2O3 matrix by CNTs and GNPs and hydrophobic nature as well as chemical inertness of these reinforcements to the aggressive environment. Further, the corrosion products are analyzed by X‐ray diffraction and Raman spectroscopy for a much deeper insight into the mechanism of corrosion protection by these carbonaceous reinforcements. For the first time, the effect of CNT and GNP reinforcement on the corrosion behavior of plasma‐sprayed coatings is investigated. [ABSTRACT FROM AUTHOR]

Summary: In this work, the role of Al2Ca and Al2(Sm,Ca,La) particles in the microstructures and electrochemical discharge performance of the as‐extruded Mg‐3wt.%Al‐1wt.%Zn‐based alloys has been reported and discussed for the anode design of Mg‐air batteries. The Al2Ca and Al2(Sm,Ca,La) particles strongly refine the grains of the as‐extruded AZ31 alloy from 9.1 ± 4.1 μm down to 5.1 ± 3.3 μm. The Al2Ca and Al2(Sm,Ca,La) particles increase the outputting cell voltage and discharge capacity of the modified AZ31 alloy. The AZ31‐Ca alloy exhibits the highest discharge capacity and anodic efficiency of 1153 mAh/g and 52.5%, respectively, at 10 mA/cm2. The promoted discharge performance should be mainly attributed to the grain refinement (improving the corrosion resistance) and fine Al2Ca phase throughout the matrix (beneficial for uniform dissolution of Mg phase). Additional Al2(Sm,Ca,La) cubic particles further stimulate the anodic kinetics and aggravate the local dissolution of Mg phase near around, resulting in the deterioration of discharge performance. [ABSTRACT FROM AUTHOR]

The microstructure, mechanical properties and corrosion behaviors of as-cast ternary Mg-2Zn-xCa (x=0, 0.2, 0.4, 0.8) alloys have been investigated in this study. Results indicate that the microstructure of Mg-Zn-Ca alloys can be significantly refined with increasing Ca concentration. Moreover, the alloys with different contents of Ca exhibit the different phases formation behaviors, i.e. a-Mg + Ca2Mg6Zn3 phases for Mg-2Zn-0.2Ca and Mg-2Zn- 0.4Ca alloys, and a-Mg + Ca2Mg6Zn3 + Mg2Ca phases for Mg-2Zn-0.8Ca alloy, respectively. Among all the alloys, the maximum ultimate tensile strength and elongation (161 MPa and 9.1%) can be attained for the Mg-2Zn-0.2Ca alloy. Corrosion tests in Hanks' balanced salt solution indicated that Ca addition is detrimental to corrosion resistance of Mg-2Zn alloy. The relationship between as-cast microstructure and properties for different Ca-containing alloys is also discussed in detail. [ABSTRACT FROM AUTHOR]

The long‐period stacking ordered (LPSO) phases have distinctive microstructures and significant effect on the promotion of mechanical properties of Mg alloys, which have received considerable attention not only as industrial materials but also as biodegradable implant materials recently. By now, numerous researchers devote to study the effects of the microstructures of LPSO phases on the mechanical properties of Mg alloys. But a few of them reveal the relationship between LPSO phases and corrosion behaviors of Mg alloys. Therefore, the knowledge of characteristics of LPSO phases and their effects on biocorrosion behaviors is essential. In this review, the current understanding about the structure, growth, transformation, and deformation of LPSO phases in Mg alloys are summarized. The recent developments of biocorrosion behaviors of Mg alloys are reviewed. The information on the immersion and corrosion mechanisms of Mg alloys are provided. The role of LPSO structures on corrosion behaviors of Mg alloys is intensively analyzed. Based on the current understandings, some problems are pointed out and suggestions for further research of Mg alloys with LPSO structures using as biomedical materials are provided. [ABSTRACT FROM AUTHOR]

Chromium nitride (CrN) coatings with different steps of intermediate argon plasma treatments were deposited with primary (200) orientation by multi-arc ion plating technique. By virtue of scanning electron microscopy, X-ray diffraction and high-resolution transmission electron microscopy, the influence of intermediate argon plasma treatments on the coating microstructures, mechanical properties and corrosion properties as well as tribological behaviors in artificial seawater solutions were systematically investigated. It was assumed that the mechanical properties, adhesion strength, corrosion and tribological performances of coatings depended on argon plasma treatment steps. High-performance coatings could be obtained by proper plasma treatment steps. The superior anti-corrosion ability of coating with appropriate treatment steps may be ascribed to the increased charge transfer resistance due to alternative interface and CrN layer and the compact microstructure. On the other hand, the excellent tribological performances in seawater conditions may be attributed to the enhanced mechanical properties. Otherwise, further increase in treatment steps was assumed to distinctly increase defects and deteriorate the coating integrity thus weakening coating properties and behaviors. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The microstructure, mechanical properties, and corrosion behaviors of solution-treated AM60-2%RE magnesium alloy containing 0.2-0.8% wt.% Zn were investigated. With the increase of Zn, the volume fraction of dispersed rod-like AlRE and granular-like AlRE phases of solution-treated AM60-2%RE + x%Zn increased, which improved the mechanical properties by dispersion strengthening. With increasing Zn content, the corrosion current density decreased, and the corrosion potential and electrochemical impedance of the alloys increased, and the corrosion resistance of solution-treated AM60-2%RE + x%Zn was improved. With the increase of Zn content, the leaf-like corrosion products of the alloy became smaller and more compact, and the content of Zn, Al, Ce, and La in corrosion products increased, which was beneficial to inhibit the corrosion progress. [ABSTRACT FROM AUTHOR]

Purpose The purpose of this paper is to investigate the effect of welding procedure on the corrosion behaviors of weathering steel 09CuPCrNi in marine atmospheric environment. The corrosion processes of weathering steel 09CuPCrNi and its welded joints in marine atmospheric environment were simulated by a salt spray dry-wet test.Design/methodology/approach The corrosion behaviors of the base metal and the welded joints at corrosion times of 2, 4, 8, 12, 24 weeks were investigated by weight loss test, electrochemical techniques, scanning electron microscope (SEM) and electron probe micro-analyzer (EPMA). The corrosion rates, as well as the morphologies and electrochemical characteristics of corrosion products, the distribution of major alloying elements in rust layer were obtained. The influence of welding on the atmospheric corrosion of 09CuPCrNi was studied.Findings The results indicate that the corrosion rate of the 09CuPCrNi welded joints decreases gradually with the corrosion time, and the major alloying elements are enriched in the inner rust layer, which are similar to that of the base metal. In the early stage during the corrosion process, the welded joints with inhomogeneous structure show the poorer corrosion resistance than that of the base metal. However, it looks the opposite way around in the late corrosion stage, when the uniform corrosion products with even thickness of the base metal tend to detach from the substrate easier and earlier and resulting in cracks, which increase the corrosion rate comparatively with that of the welded joints.Originality/value 09CuPCrNi low alloy steel is a kind of typical weathering steel developed in China which is similar to Corten A developed by USA. Nowadays, 09CuPCrNi low alloy steel is widely adopted in many fields which require welding processes. In the past years, the research of weathering steel welded joints was mainly concentrated on the strength, toughness and weldability. Less work has been done to investigate the difference of corrosion evolution and characteristics between the base metal and its welded joints. Thus, the main objective of the present work was to analyze the influence of welding on the atmospheric corrosion. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the mechanisms involved in the failure of magnetic attachments used to retain dental prostheses. Dyna magnets were retrieved from dentures that had failed after 34 months of clinical use. These magnetic attachments were prepared and sectioned so as to observe the corrosion surface and layer in order to analyze the corrosion behaviors of the attachments. The corroded surface was observed under a field emission scanning electron microscope (FE-SEM) (JSM 840A, JEOL, Japan). An X-ray diffractometer (XRD) was used to analyze the corrosion product formed due to corrosion in the oral environment. Erosion-corrosion started in the uneven portion of the stainless steel cover in the magnetic attachments composed with Nd−Fe−B alloy. Corrosion was initiated on the worn stainless steel surface, followed by spalling of magnetic material due to corrosive solution. The corrosion rate increased drastically after the corrosion product caused spalling in Nd−Fe−B alloy. Corrosion initiated in the uneven stainless steel surface as well as in the welded zone. In conclusion, the failure of magnetic attachments may occur by either welding failure or breakdown of the encapsulating material. Thus, we believe that treating the surface of magnetic attachments would resolve the corrosion problem seen in magnetic attachments to some extent. [ABSTRACT FROM AUTHOR]

The effects of alloying elements on the microstructure, mechanical properties, and corrosion behaviors of duplex stainless steels (DSSs) have been investigated in this study. Experimental alloys were prepared by varying the concentrations of the constituent elements in DSSs. Hot ductility test, tensile test, charpy impact test, and corrosion test were performed to evaluate the properties of the experimental alloys. The results showed that the extent of edge cracking of DSSs increased with the increasing value of the crack sensitivity index (CSI). The higher the hot ductility index (HDI) was, the better the hot ductility of DSSs achieved. Austenite ( γ) stabilizer generally caused a decrease in the strength and an increase in the charpy impact absorbed energy of the stainless steel. On the contrary, ferrite ( α) former exerted its beneficial effect on the strength but became detrimental to the toughness of DSSs. The presences of sulfur and boron also caused a decrease in the impact energy, but nitrogen and carbon hardly affected the toughness within the concentration range tested in this study. The value of pitting nucleation potential ( E np ) of different nitrogen contents in 3.5 wt.% NaCl solution at room temperature was almost the same, but the value of pitting protection potential ( E pp ) among these alloys was increased with increasing the content of nitrogen. The susceptibility to stress corrosion cracking (SCC) of DSSs was high when tested in boiling 45 wt.% MgCl2 solution. On the other hand, the time to failure of the experimental steels in 40 wt.% CaCl2 solution at 100 °C was longer than that in MgCl2 solution. Nitrogen could affect the SCC behavior of DSSs in CaCl2 solution through the combinative effects by varying the pitting resistance and the slip step dissolution. An optimum nitrogen (N) content of 0.15 wt.% was found where the highest SCC resistance could be obtained. Although γ phase exhibited better resistance to SCC, cracks were found to penetrate through α and γ grains or to propagate along the α/γ interface. As a result, a mixed transgranular plus intergranular mode of fracture surface was observed. [ABSTRACT FROM AUTHOR]

The corrosion behaviors of TA2 titanium were investigated by in situ electrochemical measurements in a solution of 2.3 ppm Li+ and 1500 ppm B3+ at a temperature of up to 300 °C. The morphology, phase structure, and composition of the oxide film, after 800 h exposure time in a solution at 300 °C and 14 MPa, were characterized by scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), etc. The growth mechanism of the oxide film based on the activation energy was discussed. The potentiodynamic polarization and electrochemical impedance spectroscopy analyses showed that the corrosion resistance of titanium significantly weakened when increasing the solution temperature from 30 to 300 °C, but it increased in the initial stage of holding time (0–66 h) at 300 °C, then gradually decreased (66–378 h), and reached a stable state after 378 h. The oxide film, which was about 5 μm thick, consisted of anatase phase and a small amount of B2O3. The growth mechanism is a combination of layer by layer and island growth. [ABSTRACT FROM AUTHOR]

Selective laser melting (SLM) is an ideal method to directly fabricate products with high geometrical complexity. With low density and good corrosion resistance, aluminum alloys are widely used as important structural materials. Microstructures and mechanical properties of SLMed aluminum alloys have been recently widely studied. Corrosion behavior as a vital concern during the service of SLMed aluminum alloy parts has also drawn many attentions. Previous studies have found that SLM-processed aluminum alloys exhibit better corrosion resistance compared to the casted and wrought counterparts for both Al-Si alloys and high strength 2xxx Al alloys, which is mainly due to the unique microstructure features of SLMed Al alloys. For Al-Si alloys, with different shapes of Si networks, the different building planes show discrepant corrosion behaviors. Owing to the rougher surface with relatively larger numbers of defects, the as-printed surface is vulnerable to corrosion than the polished. Heat treatment has a negative effect on corrosion resistance due to the breakup of Si networks. The microstructure features correlated with the corrosion behaviors were also reviewed in this paper. Some suggestions on the future study of corrosion behaviors of SLMed Al alloys were put forward. [ABSTRACT FROM AUTHOR]

The objective herein is to evaluate the effect of silicon on the corrosion behavior of dual‐phase steels. For this purpose, five different steels with various Si content ranging from 0.34 to 2.26 wt% are intercritically annealed at 780 °C for 15 min. It is clarified that the mechanism of the effect of Si on the corrosion behavior of dual‐phase steels is a mutual mechanism. The increase in Si content (from 0.34% to 0.91%) initially reduces corrosion resistance due to a decrease in the volume fraction of martensite. However, according to microcapillary studies, a further increase in Si content (from 0.91% to 2.26%) reduces the potential difference between ferrite and martensite and, as a result, reduces the galvanic couple between them. Therefore, corrosion resistance improves by increasing Si content in the range of 0.91%–2.26%. It is also shown that in the corroded surface of the low‐silicon sample, γ‐FeOOH is mainly formed, whereas with an increase in Si content, this compound reduces and α‐FeOOH rises. Also, β‐FeOOH, silicon oxide and Fe3O4 are formed in the high‐silicon sample. The study of the corroded surface topography depicts that surface roughness in a high‐Si sample is less than low‐Si sample. [ABSTRACT FROM AUTHOR]