Effect Of Cr Addition Research Articles

Effect of Cr addition on microstructure, mechanical properties, and corrosion behavior of weld metal in weathering steel of high-speed train bogie

Effect of Cr addition on microstructure, mechanical properties, and corrosion behavior of weld metal in weathering steel of high-speed train bogie

Effect of Cr Additions on the Coarsening Resistance of β′ Precipitates in Ferritic Fe–Ni–Al Alloys

The effect of Cr additions ON the coarsening of β′(NiAl) precipitates in (Fe,Cr)‐α matrix is studied using Fe–10%Ni–15%Al–15%Cr (FAN15Cr) and Fe–10%Ni–15%Al–22%Cr (FAN22Cr) alloys. Specimens are homogenized and subsequently aged at 850, 900, and 950 °C for different periods of time. The characterization is carried out with conventional and high‐resolution scanning electron microscopy, transmission electron microscopy, and Vickers hardness tests. Results indicate that the addition of Cr leads to an increase in the activation energy and the coarsening kinetics at high temperatures. The precipitate morphology during aging evolves from spheres with a random distribution, followed by cuboids aligned in preferential orientations and the formation of clusters. As aging progresses further, the morphology changes to semirounded precipitates with a polyhedral surface as revealed by the etching process. Transmission electron microscopy results reveal the formation of a dislocation network indicating a state of semicoherency in the precipitate–matrix interface. The activation energy for the coarsening process is determined from the coarsening kinetic constants. While the activation energy for the coarsening in FANCr15 is close to similar alloys, the value for FAN22Cr is unusually high and probably related to the dislocation networks observed.

Effect of Cr addition on the microstructure and mechanical properties of MoNbVTa0.5Crx refractory high-entropy alloys

To increase strength and decrease density of traditional refractory high-entropy alloys (RHEAs), the MoNbVTa0.5Crx RHEAs were synthesized by mechanical alloying (MA) and spark plasma sintering (SPS). The effect of Cr content on microstructure and mechanical properties of the MoNbVTa0.5Crx RHEAs was systematically studied. The results showed the addition of Cr could refine the microstructure, decrease density and increase strength of RHEAs. The microstructure of the sintered alloy was composed of BCC phase and a small amount of oxide phase (Ta2VO6), and Ta2OV6 (200) has a semi-coherent relationship with BCC phase (110), with a lattice mismatch degree of 7.34 %. The compressive yield strength of the MoNbVTa0.5Crx RHEAs initially increased and then decreased with increasing Cr content. The MoNbVTa0.5Cr0.75 RHEAs demonstrated the best mechanical properties, and the compressive yield strength and ultimate compressive strength at room temperature were 3180 MPa and 3596 MPa, respectively, which were far higher than traditional WNbMoTaV RHEAs. And the density of MoNbVTa0.5Cr0.75 RHEAs was 21 % lower than that of sintered WNbMoTaV RHEAs. The strengthening mechanism of sintered MoNbVTa0.5Crx RHEAs involved O/C atoms interstitial solid solution strengthening, grain boundary strengthening, and metal atoms solid solution strengthening, while the contribution of oxide precipitation strengthening was negligible.

Effects of Cr Addition on the Microstructure and Mechanical Properties of an Al-Si-Cu-Mg Alloy.

The effects of chromium (Cr) addition ranging 0.1-0.3 wt.% on the microstructure and mechanical properties of Al-7Si-4Cu-0.25Mg (wt.%) alloy have been investigated. The cast Cr-free alloy consisted of α-Al, eutectic Si, Q-Al5Mg8Cu2Si6 and θ-Al2Cu phases. Doping of Cr resulted in the appearance of a polyhedron-shaped α-Al13Cr4Si4 phase with a cubic structure. The Al13Cr4Si4 particles were found to embed with Al2Cu blocks and bring about size reduction for the Al2Cu blocks. The area fraction of Al13Cr4Si4 monotonously increased with Cr content. After T6 treatment, the Al2Cu blocks almost fully dissolved and transformed to θ'-Al2Cu precipitates in the Cr-containing alloys. TEM observation revealed relatively large-sized θ' precipitates attached to Al13Cr4Si4 dispersoids. The Cr-containing alloys showed impressive mechanical properties, with the peak strength up to 452 MPa at room temperature. The ductility exhibited an increasing trend with Cr content, but the strength dropped dramatically when the Cr content reached 0.3 wt.%. It is suggested that the strength contribution from the Al13Cr4Si4 phase is limited, especially at an elevated temperature.

The Effect of Cr Addition on the Strength and High Temperature Oxidation Resistance of Y2O3 Dispersion Strengthened Mo Composites.

Y2O3 dispersion-strengthened Molybdenum (Mo) composites were prepared by the mechanical alloying of Mo and Y powders then consolidation by spark plasma sintering. The effects of Chromium (Cr) addition (0 wt. %, 5 wt. %, 10 wt. % and 15 wt. %, respectively) on the mechanical performance and high-temperature oxidation resistance of Mo-Y2O3 were investigated. The introduction of Cr had a significant influence on the mechanical property and oxidation resistance of the Mo-Y2O3 composite. The highest bending strength reached 932 MPa when the addition of Cr content was 5 wt. % (Mo-5Cr-1Y sample). This improvement is likely attributable to the dual mechanism of grain refinement and solid solution strengthening. Moreover, the Mo-5Cr-1Y sample showed the thinnest oxide layer thickness after high-temperature oxidation tests, and exhibited the best oxidation resistance performance compared with the other samples. First principle calculation reveals that Cr could improve the Mo-MoO3 interface bonding to prevent rapid spalling of the oxide layer. Meanwhile, Cr also facilitates the formation of the dense Cr2(MoO4)3 layer on the surface, which can inhibit further oxidation.

Effect of Cr content on microstructure, mechanical, and corrosion properties of CoCrxFeMnNi high-entropy alloys fabricated by selective laser melting

The method of using mixed powder for SLM in-situ alloying to prepare high entropy alloys has been verified to be feasible. In this investigation, the effect of Cr addition on microstructure uniformity, mechanical properties, and corrosion resistance of CoCrxFeMnNi High-entropy alloy (with x = 0.4, 0.7, 1.0, 1.3 at. %) prepared by the SLM in-situ alloying technique has been thoroughly investigated. X-ray diffraction and scanning electron microscopy suggest that all CoCrxFeMnNi HEAs samples are composed of a FCC matrix and little residual Cr particles, and all elements of the FCC matrix are evenly distributed, accompanied by a very small amount of Mn evaporation. Electrochemical corrosion tests have shown that with an increase in Cr content, the corrosion resistance of the alloy is significantly improved. The CoCr1.3FeMnNi HEAs possess the best corrosion resistance against the attack of the Cl ion, with a corrosion rate 0.671 × 10−3 mm / year. Furthermore, the Cr element can significantly improve the microhardness, tensile strength, and plasticity of CoCrxFeMnNi HEAs. The CoCr1.3FeMnNi HEAs possess the best mechanical properties, with microhardness 217.8 HV0.5, tensile strength 691 MPa and elongation rate 18.9%, respectively.

Effects of Cr addition on structure, magnetic properties and corrosion resistance of a Fe85.5B13Cu1.5 nanocrystalline alloy

The melt-spun structure of a Fe85.5B13Cu1.5 alloy was regulated by the addition of corrosion-resistant Cr with a moderate enhancement in amorphous-forming ability, which further refines the nanostructure and improves the soft magnetic properties and corrosion resistance of corresponding nanocrystalline alloys. The results show that high-number-density α-Fe grains in size of below 10 nm are formed in the amorphous matrix of melt-spun Fe85.5-xB13Cu1.5Crx (x = 0–6) alloy ribbons, and the grain size and number density gradually decrease with the increase in Cr content. After annealing, the α-Fe average grain size (Dα-Fe) and coercivity (Hc) of corresponding nanocrystalline alloys reduce significantly with increasing x from 0 to 3, and the reduction becomes less pronounced within x = 3–6, while the saturation magnetic flux densities (Bs) steadily decreases as x increases from 0 to 6. A Fe82.5B13Cu1.5Cr3 nanocrystalline alloy with the Dα-Fe of 14.9 nm possesses excellent comprehensive soft magnetic properties with the Hc and Bs of 13.8 A/m and 1.74 T, respectively. The fine nanostructure and good magnetic softness results from the optimum combination of pre-existing α-Fe competitive growth and Cr-inhibited atom diffusion. The nanocrystalline alloys show improved corrosion resistance in NaCl solution compared to their respective melt-spun precursors, and the addition of Cr further enhances the corrosion resistance. The alloyed Cr also reduces the annealing embrittlement of the nanocrystalline alloys.

Effect of Cr addition on the microstructure evolution, precipitation behavior and properties of Cu–Ag alloy

This investigation systematically explores the impact of minor Cr additions on the microstructural evolution, precipitation kinetics, mechanical properties, and electrical properties of Cu–Ag alloys, with a specific focus on Cu–6 %Ag-(0.4 %Cr). The alloys underwent casting through a vacuum induction furnace, followed by meticulous treatments involving solution heat and aging at varied temperatures and durations. Results indicate a significant improvement in the mechanical properties of Cu–Ag alloy upon Cr addition, with only a slight reduction in electrical conductivity. As per differential scanning calorimetry (DSC) measurements, the activation energy for continuous precipitation in the Cu–Ag–Cr ternary alloy is slightly higher than that in Cu–Ag. However, Cu–Ag–Cr lacks peaks corresponding to the discontinuous phase. Microstructural analysis unveils that Cr incorporation suppresses the discontinuous precipitation of Ag, fostering continuous precipitation during aging. Moreover, both micro-sized and nano-sized Cr particles were detected in the Cu–Ag–Cr alloy, contributing to the formation of finely spaced continuous Ag precipitates and fine Cr precipitates. This intricate microstructure imparts higher hardness and strength to the alloy compared to Cu–Ag. Specifically, following aging treatment at 450 °C for 2 h, the Cu–6 %Ag-0.4 %Cr alloy exhibited a remarkable increase of 76.1 % in hardness, 43.6 % in strength, and a moderate decrease of 15.8 % in conductivity.

Effects of Cr-addition on ageing response of an Al–Si–Mg die cast alloy

Chromium (Cr) is rarely added to Al–Si die cast alloys as it has a strong tendency to induce the formation of coarse-sized sludge particles. In the present study, high pressure die-cast samples made of Al-7wt.%Si–Cr–Mg alloys with varied Fe contents (0.11 wt%, 0.26 wt% and 0.32 wt%) were tensile tested under as-cast and T5 heat-treated conditions, in comparison to those made of Al-7wt.% Si–Mn–Mg alloy with a constant Fe content (0.11 wt%). The results demonstrated that under the as-cast condition, the Al–Si–Cr alloys with higher Fe contents can achieve comparable tensile properties as the Al–Si–Mn alloy with strictly controlled Fe level. However, after a T5 heat treatment (205 °C for 60 min), the increment in yield strength is less for the Al–Si–Cr alloys in relative to the Al–Si–Mn alloy, regardless of Fe contents. Scanning electron and scanning transmission electron microscopic characterizations were conducted on the as-cast and heat-treated microstructures, aiming to understand the undermined ageing response caused by Cr addition.

Effect of Cr addition on oxidation and tribological properties of MoB2-z films by magnetron sputtering

Molybdenum diboride films are anticipated to be used in cutting applications as a potential replacement for nitride coatings due to their high hardness and good high-temperature stability. However, the films undergo severe oxidation at 600 °C, which does not guarantee good wear resistance. The addition of Cr element is chosen to improve the film's oxidation resistance, which in turn improves the film's friction and wear performance at higher temperatures. The Mo-Cr-B films were prepared by magnetron sputtering by changing Cr target current. The oxidation properties of the films at 600 °C and the tribological performance and the wear mechanism at 25 °C, 400 °C and 600 °C were investigated. The results reveal that the MoB2-z film and Cr-alloyed MoB2-z films have higher hardness (>30 Gpa). And the Mo0.67Cr0.33B2-z film and Mo0.51Cr0.49B2-z film exhibit much greater oxidation resistance at 600 °C than do MoB2-z film and Mo0.79Cr0.21B2-z film. The Mo0.67Cr0.33B2-z film demonstrates good wear resistance at 25 °C, 400 °C and 600 °C. Especially at 600 °C, the Mo0.67Cr0.33B2-z film clearly outperforms the MoB2-z film in terms of wear resistance.

Effects of Cr additions on Corrosion and Erosion-Corrosion Behaviors in the Weld Heat-Affected Zone of Hadfield Steel in Brine Environments

The corrosion and erosion-corrosion behaviors in the weld heat-affected zone (HAZ) of Hadfield steels with varying Cr contents (1, 2, and 3 wt%) were examined. Various experimental methods, including electrochemical polarization, impedance, and weight loss measurements, were utilized. Two types of isothermal heat treatments were conducted in a box furnace to simulate the intercritical HAZ, known to be the most vulnerable region in terms of mechanical properties and environmental stabilities, and large-scale samples for the erosion-corrosion experiment were fabricated. The results showed that increasing the Cr content improved the resistance to corrosion and erosion-corrosion, but there was an inflection point where adding more Cr had the opposite effect. Up to 2 wt%, a higher resistance was exhibited owing to the formation of a thin and protective oxide scale enriched with Cr that adhered to the steel surface. On the other hand, adding 3 wt% of Cr resulted in decreased resistance. This was due to the formation of coarse M<sub>7</sub>C<sub>3</sub> (M: Cr) precipitated along the grain boundary, which caused the development of a thick and unstable oxide scale that detached locally. Based on these findings, it is essential to optimize the Cr content to ensure a high resistance to corrosion and erosion-corrosion in the HAZ of Hadfield steel.

Processing of WC with Fe-based alternative binders: Adjustment of C content and effect of Cr addition

Alternative hard materials to traditional WC-Co are one of the main goals in the investigation efforts of both scientific and industrial communities. In this investigation, WC-based materials were designed and processed with different Fe alloys employing a powder metallurgy route. Two candidates were selected: FeCrAl and FeNiCr. The former showed the formation of aluminium oxides, which hindered a homogeneous metal-ceramic distribution. On the other hand, FeNiCr led to dense and optimised samples which were further characterised in terms of their mechanical properties and corrosion resistance. They revealed an excellent combination of hardness and toughness, comparable or even superior to industrial compositions containing Co. Selected Cr addition induced some segregation and formation of secondary carbides –in consonance with thermodynamic simulation results and as evidenced by optical microscopy, XRD and TEM analyses– with a decrease in the TRS value. However, massive nanoindentation tests revealed that it also led to improved intrinsic hardness of binder and composite (metal-ceramic) phases, as well as enhanced corrosion resistance in acidic media compared to Cr-free alternative and reference hardmetals.

Determination of microstructure and mechanical and thermophysical properties of Al–Si–Mg-XCr alloy

The study added different proportions of Cr to the Al–Si–Mg eutectic alloy and applied heat treatment to the quaternary alloy. So, the Al–Si–Mg eutectic alloy's microstructure and morphology were looked at after Cr was added and it was heated. In addition, the hardness, tensile strength, fracture surface analysis, and thermoelectric properties of newly produced Al-12.95 % Si-4.96 % Mg-X%Cr alloys were also determined. In the newly formed alloy, along with the expected Si and Mg2Si phases in the Al matrix phase, a randomly distributed CrSi2 binary intermetallic phase in a white hexagonal structure was observed with the effect of Cr addition. Additionally, a magnesium-rich Al9FeMg3Si5 intermetallic phase was observed, which we think was formed by the effect of Fe impurity atoms. Hardness and tensile strength values, which are the mechanical properties of the alloy, increased significantly after heat treatment. The hardness value of the 0.5 % Cr-added sample increased by approximately 77 % and reached 107.95 ± 6.0 kg/mm2. At the same time, the hardness value of the intermetallic CrSi2 phase in the quaternary Al-12.95 wt%Si-4.96 wt%Mg-1.0%Cr alloy was found to be 794.3 ± 30 kg/mm2. Similarly, the maximum tensile strength value of the 0.5 % Cr-added sample after heat treatment increased by approximately 105 % and reached 160.53 MPa. Melting temperatures (Tm) (K), fusion enthalpy (ΔH) (J/g), and specific heat Cpl (J/gK) were determined for non-heat-treated materials. The 0.5, 1.0, and 1.5 Cr-added samples had Tm of 563.38 °C, 558.44 °C and 572.61 °C, respectively. The ΔH value of samples with 0.5 %, 1.0 % and 1.5 % Cr addition is 605.70 (J/g), 579.92 (J/g) and 552.24 (J/g), respectively. Cpl was 0.724 J/g.K, 0.698 J/g.K and 0.653 J/g.K for 0.5 %, 1.0 %, and 1.5 % Cr-added samples. In both heat-treated and non-heat-treated samples, Cr enhanced electrical resistance.

Effect of Cr addition on the Corrosion-Wear Behaviors of 18Mn(V, Mo) Steel in a Seawater Environment

The objective of this study was to examine the wear-corrosion behavior of 18Mn(V, Mo) steel, which had a minor amount of Cr addition (< 3 wt%), in an artificial seawater environment, and compare it to conventional carbon steel. A variety of electrochemical experiments, including linear polarization resistance, impedance spectroscopy, and galvanostatic polarization, were conducted, along with weight loss measurements after immersion and wear-corrosion testing. These tests aimed to determine the static corrosion and wear-corrosion mechanisms of 18Mn(V, Mo) steel with respect to Cr addition. The results of this study indicated that the addition of Cr to 18Mn(V, Mo) steel refined the V4C3 particles in the microstructure, which led to an increase in surface hardness. Moreover, the 18Mn(V, Mo) steel with Cr addition exhibited the lowest corrosion and corrosion-wear losses, compared to 18Mn(V, Mo) steel without Cr and conventional carbon steel. This beneficial effect was primarily attributed to the formation of a thin Crenriched corrosion scale that adhered to the underlying steel. This corrosion scale served as a protective barrier against the penetration of corrosive species and as a lubricant for mechanical wear. The 18Mn(V, Mo) steel with Cr addition has potential application in various industrial fields, particularly in marine and offshore environments, owing to its low corrosion-induced wear loss rate in a brine environment.

Effect of Cr addition and heat treatment on the physical properties of Fe-Al melt-spun ribbons

Iron-based alloys with compositions close to Fe75Al25 (at.%) attract much attention due to their unique properties useful, e.g., for high-temperature or high damping engineering applications. Their mechanical, electron transport and magnetic properties strongly depend on the structural characteristics. In this paper we carried out a comparative study of the physical properties of the as spun ribbons Fe70Al30 and Fe70Al20Cr10 (at.%) alloys. The ribbons were produced using the melt spinning technique and were characterized by SEM, X-ray diffraction, differential scanning calorimetric, resistivity measurement and vibrating sample magnetometer. The addition of Cr to Fe70Al30 has a significant influence on atomic ordering, increases the electrical resistivity and a strong influence on the magnetic behavior.

Effect of Cr addition on corrosion behavior of cupronickel alloy in 3.5 wt% NaCl solution

Cupronickel alloys have a variety of applications in marine engineering due to their good mechanical and corrosion properties. In this work, the effect of Cr on the corrosion behavior of Cu–10Ni–1.6Fe–0.5Mn alloy in 3.5 wt% NaCl solution was investigated through electrochemical and surface characterization. The results indicate that Cu–10Ni–1.6Fe–0.5Mn–0.3Cr alloy has better corrosion resistance performance compared to Cu–10Ni–1.6Fe–0.5Mn alloy in NaCl solution. The addition of Cr reduces the corrosion current density of cupronickel alloys from 7.82 μA/cm2 to 7.10 μA/cm2. The better corrosion resistance performance of the Cu–10Ni–1.6Fe–0.5Mn–0.3Cr alloy could be mainly attributed to the incorporation of Cr3+ ions in Cu2O lattice during corrosion. The corrosion product film of Cu–10Ni–1.6Fe–0.5Mn–0.3Cr alloy mainly contains the compounds including Cu2O, NiO, γ-FeOOH, Cr2O3, and Cu2(OH)3Cl. The formation of Cr2O3 can further enhance the stability of corrosion film and improve the corrosion properties of the alloy.

Effect of Cr addition on the γ′ strengthened CoNiCrAlMo compositionally complex alloy

The present study illustrates the effect of varying Cr content in Co51-x Ni30Al10Mo5Nb2Ti2Cr x (x = 2, 5, and 8 at.-%) compositionally complex alloys (CCAs). STEM-EDS analysis suggests a change in Mo partitioning from equal in both the phases (γ and γ′) in CCA-2Cr to the γ phase in CCA-5Cr and CCA-8Cr alloys. This peculiar compositional partitioning with Cr content beyond 2% brings a change in γ′ precipitate morphology from cuboidal to spheroidal in CCAs. The shape change-induced reduction in strain energy rendered a decrease in γ′ coarsening rate by ∼ 1/2, i.e. from 11.5 to 4.6 nm3/s in the CCA-2Cr and CCA-8Cr alloys, respectively. All three alloys show an anomalous increase in 0.2% proof stress (PS) with temperature and achieve peak values at 770°C.

Modification and refinement of Fe-containing phases, mechanical properties and strengthening mechanisms in Al–Fe alloys via Cr alloying and continuous rheo-extrusion

Given limited resources, it is necessary to increase the recycling of wasted aluminum alloy products. Due to the increase in Fe content during recycling, the formation of needle-, lath- and flake-shaped Fe-rich intermetallics reduces the mechanical properties of alloys. In this work, the effects of Cr addition on the microstructural evolution and mechanical properties of as-cast and rheo-extruded Al–1.5Fe (wt%) alloys were investigated. The results indicated that with increasing the Cr content from 0 wt% to 1.2 wt%, the average size of α-Al grains and Al13Fe4 phases first decreased and then increased. When the Cr content was 0.4 wt%, the refined microstructure was obtained; the optimized ultimate tensile strength, yield strength, and elongation of the as-cast alloy were 103.5 MPa, 60.2 MPa, and 36.2%, respectively. In addition, in the as-cast Al–1.5Fe–0.4Cr (wt%) alloy, Cr adsorption on the surface of Al13Fe4 phases was found, which caused the growth inhibition for Al13Fe4 phases. When the Cr content was larger than 0.8 wt%, the formation of coarse Al–Fe–Cr ternary phases resulted in the deterioration of mechanical properties. In order to further tailor the Al13Fe4 phases, the continuous rheo-extrusion of Al–1.5Fe(–0.4Cr) (wt%) alloy was performed. The rheo-extruded Al–1.5Fe–0.4Cr (wt%) alloy exhibited a superior combination of strength and ductility. The strengthening mechanisms induced by Cr addition were discussed. Grain boundary strengthening and dislocation strengthening were responsible for the enhancement in yield strength of the rheo-extruded alloy.

Effect of Cr Addition on Properties and Tribological Behavior at Elevated Temperature of Boride Layers Grown on Borosintered Powder Metallurgy Alloys

Effect of Cr Addition on Properties and Tribological Behavior at Elevated Temperature of Boride Layers Grown on Borosintered Powder Metallurgy Alloys

Effect of Cr Addition on the Milling Process and Properties of Nanostructured Cu Alloys Prepared by Mechanical Alloying

Effect of Cr Addition on the Milling Process and Properties of Nanostructured Cu Alloys Prepared by Mechanical Alloying