Subjects -> METALLURGY (Total: 58 journals)
Showing 1 - 10 of 10 Journals sorted alphabetically
Acta Metallurgica Slovaca     Open Access   (Followers: 2)
Advanced Device Materials     Open Access   (Followers: 6)
American Journal of Fluid Dynamics     Open Access   (Followers: 44)
Archives of Metallurgy and Materials     Open Access   (Followers: 9)
Asian Journal of Materials Science     Open Access   (Followers: 4)
Canadian Metallurgical Quarterly     Hybrid Journal   (Followers: 21)
Complex Metals     Open Access   (Followers: 2)
Energy Materials : Materials Science and Engineering for Energy Systems     Hybrid Journal   (Followers: 24)
Graphene and 2D Materials     Open Access   (Followers: 6)
Handbook of Ferromagnetic Materials     Full-text available via subscription   (Followers: 1)
Handbook of Magnetic Materials     Full-text available via subscription   (Followers: 2)
High Temperature Materials and Processes     Open Access   (Followers: 6)
Indian Journal of Engineering and Materials Sciences (IJEMS)     Open Access   (Followers: 11)
International Journal of Metallurgy and Alloys     Full-text available via subscription   (Followers: 1)
International Journal of Metals     Open Access   (Followers: 7)
International Journal of Minerals, Metallurgy, and Materials     Hybrid Journal   (Followers: 11)
International Journal of Mining and Geo-Engineering     Open Access   (Followers: 4)
Ironmaking & Steelmaking     Hybrid Journal   (Followers: 5)
ISIJ International - Iron and Steel Institute of Japan     Full-text available via subscription   (Followers: 26)
Izvestiya Vuzov. Poroshkovaya Metallurgiya i Funktsional’nye Pokrytiya (Proceedings of Higher Schools. Powder Metallurgy аnd Functional Coatings)     Full-text available via subscription   (Followers: 2)
JOM Journal of the Minerals, Metals and Materials Society     Hybrid Journal   (Followers: 35)
Journal of Central South University     Hybrid Journal   (Followers: 1)
Journal of Cluster Science     Hybrid Journal  
Journal of Heavy Metal Toxicity and Diseases     Open Access  
Journal of Iron and Steel Research International     Hybrid Journal   (Followers: 11)
Journal of Materials & Metallurgical Engineering     Full-text available via subscription   (Followers: 2)
Journal of Materials Processing Technology     Hybrid Journal   (Followers: 21)
Journal of Metallurgical Engineering     Open Access   (Followers: 4)
Journal of Sustainable Metallurgy     Hybrid Journal   (Followers: 3)
Materials Science and Metallurgy Engineering     Open Access   (Followers: 6)
Metal Finishing     Full-text available via subscription   (Followers: 20)
Metallurgical and Materials Engineering     Open Access   (Followers: 7)
Metallurgical and Materials Transactions A     Hybrid Journal   (Followers: 41)
Metallurgical and Materials Transactions B     Hybrid Journal   (Followers: 32)
Metallurgical and Materials Transactions E     Full-text available via subscription   (Followers: 2)
Metallurgical Research and Technology     Full-text available via subscription   (Followers: 8)
Metallurgy and Foundry Engineering     Open Access   (Followers: 2)
Mining, Metallurgy & Exploration     Hybrid Journal  
Powder Diffraction     Full-text available via subscription   (Followers: 1)
Powder Metallurgy     Hybrid Journal   (Followers: 36)
Powder Metallurgy and Metal Ceramics     Hybrid Journal   (Followers: 8)
Powder Metallurgy Progress     Open Access   (Followers: 5)
Practical Metallography     Full-text available via subscription   (Followers: 6)
Rare Metals     Hybrid Journal   (Followers: 3)
Revista de Metalurgia     Open Access  
Revista del Instituto de Investigación de la Facultad de Ingeniería Geológica, Minera, Metalurgica y Geográfica     Open Access  
Revista Remetallica     Open Access   (Followers: 1)
Revue de Métallurgie     Full-text available via subscription  
Russian Metallurgy (Metally)     Full-text available via subscription   (Followers: 4)
Science and Technology of Welding and Joining     Hybrid Journal   (Followers: 7)
Steel Times lnternational     Partially Free   (Followers: 19)
Transactions of the IMF     Hybrid Journal   (Followers: 14)
Transactions of the Indian Institute of Metals     Hybrid Journal   (Followers: 5)
Tungsten     Hybrid Journal  
Universal Journal of Materials Science     Open Access   (Followers: 3)
Welding in the World     Hybrid Journal   (Followers: 7)
Welding International     Hybrid Journal   (Followers: 11)
Вісник Приазовського Державного Технічного Університету. Серія: Технічні науки     Open Access  
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Journal of Iron and Steel Research International
Journal Prestige (SJR): 0.569
Citation Impact (citeScore): 1
Number of Followers: 11  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1006-706X - ISSN (Online) 2210-3988
Published by Springer-Verlag Homepage  [2626 journals]
  • Strength, strain capacity and toughness of five dual-phase pipeline steels
    • Abstract: Abstract The effect of microstructures on strength, strain capacity and low temperature toughness of a micro-alloyed pipeline steel was elucidated. Five various dual-phase microstructures, namely, acicular ferrite and a small amount of (around 2 vol.%) polygonal ferrite (AF + PF), polygonal ferrite and bainite (PF + B), polygonal ferrite and martensite/austenite islands (PF + M/A), polygonal ferrite and martensite (PF + M) and elongated polygonal ferrite and martensite (ePF + M), have been studied. Experimental results show that AF + PF microstructure has high yield strength and excellent low temperature toughness, whereas its yield ratio is the highest. Polygonal ferrite-based dual-phase steels, PF + B, PF + M/A and PF + M microstructures show better strain capacity and low temperature toughness. The strain capacity and low temperature toughness of ePF + M microstructure are the worst due to its high strength. The relationship between microstructure, strength, strain capacity and toughness has been established. Based on the results, the optimum microstructure for a better combination of strength, strain capacity and toughness is suggested to be the one having appropriate polygonal ferrite as second phase in an acicular ferrite matrix.
      PubDate: 2021-01-16
       
  • Structure and electrochemical characteristics of Mg–Ti–Ni-based
           electrode alloys synthesized by mechanical milling
    • Abstract: Abstract The vacuum induction melting was adopted to fabricating Mg50−xTixNi45Al3Co2 (x = 0, 1, 2, 3, 4 at.%) composites protected by the high-purity helium atmosphere. Subsequently, the surface modification treatment of the as-cast alloys was carried out by mechanically coating nickel. The amorphous and nanocrystalline Mg50−xTixNi45Al3Co2 (x = 0–4) + 50 wt.% Ni hydrogen storing alloys as the negative materials in batteries were prepared through ball milling, and the influences of milling time and Ti dosage on the structure and electrochemical hydrogen storing behaviors of the corresponding samples were studied in detail. The electrochemical testing reveals that the as-milled alloys have excellent performances and can finish the electrochemical hydrogenation and dehydrogenation at indoor temperature. In the first cycle without activation, the ball milling alloy obtains the maximum value of discharge capacity. Discharge capacity and cyclic steadiness of the composites conspicuously grow as Ti content and milling duration increase. Concretely, the capacity retaining rate at 100th cycle and the discharge capacity of 30 h milling samples augment from 53% to 78% and from 435.2 to 567.2 mAh/g with changing Ti content from 0 to 4. The same performances of the alloy (x = 4) are enhanced from 61% to 78% and from 379.9 to 567.2 mAh/g, respectively, with extending milling duration. Moreover, high rate discharge ability, potential-step measurements, potentiodynamic polarization curves and electrochemical impedance spectrum manifest that the electrochemical kinetics properties can achieve significant amelioration as Ti content varies and milling duration is extended.
      PubDate: 2021-01-16
       
  • Effect of furnace atmosphere on sintering process of chromium-containing
           steel via powder metallurgy
    • Abstract: Abstract During a powder metallurgy process such as sintering, the primary role played by the atmosphere in furnace is to prevent an excessive oxidation of powder compacts in case of the formation of oxides as residuals on powder surfaces. In particular, the adjustment of furnace atmosphere is the key to eliminate the phenomenon “decarburization” likely to occur in carbon-containing compacts. A continuous belt furnace was used to stabilize the potentials of carbon and oxygen in zones divided by sintering, delubrication, and cooling. Chromium and manganese, which are sensitive to oxygen, were added to improve mechanical properties in a cost-effective way. Powders of steel containing chromium were sintered in an atmosphere composed of CO, O2, and H2. The effects of atmosphere, lubricant, and graphite on oxidation (or reduction) and decarburization (or carburization) were investigated. Superior quality was achieved under the control of delubrication atmosphere. It is indicated that in a protective atmosphere, the chemical reactions occurring at various stages took remarkable effect on the quality of sintered compact. The potentials of oxygen and carbon in a continuous belt furnace were monitored and analyzed using an on-line thermal measuring unit consisting of thermocouple, oxygen probe, and carbon monoxide sensor. The avoidance of oxidation and decarburization promises desired microstructure and carbon content and satisfactory properties through the adjustment of technical parameters, e.g., the composition of gases in delubrication and various sintering zones, the rate of gas inlet, and cooling rate.
      PubDate: 2021-01-10
       
  • Preparation of stainless steel mesh-supported ZnO and graphene/ZnO nanorod
           arrays with high photocatalytic performance
    • Abstract: Abstract A series of zinc oxide (ZnO) nanorods arrays with different morphologies are synthesized on stainless steel mesh via a facile electrodeposition method. The influences of electrodeposition parameters on the diameter, length, density and morphology of obtained ZnO nanorods are investigated systematically. The results indicate that the electrodeposition potential is the key factor for the morphology of the obtained ZnO nanorods, which further showed the effect on the photocatalytic property of the obtained samples. Meanwhile, the prepared ZnO nanorods array exhibits an excellent photocatalytic activity for methylene blue (MB) in ultraviolet light. The degradation efficiency for MB solution reaches 95.1% under the irradiation of ultraviolet light for 120 min. In addition, the photocatalytic property of the prepared ZnO nanorods can be extended to the visible light region after the modified with graphene oxide (GO). The obtained GO/ZnO composite also shows remarkable photocatalytic activity and photostability. The photodegradation efficiency for MB is 83.6%, and the catalytic performance retains 97.3% of its initial photocatalytic activity after five cycles.
      PubDate: 2021-01-08
       
  • Effect of Zr-deoxidation on microstructure and mechanical behavior of
           microalloyed heavy plates with low impurity content
    • Abstract: Abstract The significance of different deoxidation practises on the ductility and impact toughness of next generation of microalloyed heavy plates was elucidated to explore the best deoxidation practice in obtaining required mechanical properties, which was judged by the combined effects of composition, size and number density of inclusions on the ductility of the experimental high-strength low-alloy steel. The impurity contents, i.e., total O + N + S contents, of 82 × 10−6 (Al-killed) and 118 × 10−6 (Zr-killed) have been induced to characterize both the steels. Ductility was characterized using tensile and Charpy V-notch testing. The number, size and composition of the inclusions were characterized using a field emission scanning electron microscope with an energy dispersive spectrometer. In the Al-killed steel, the inclusion structure consisted of titanium nitrides, stringer calcium aluminates and elongated manganese sulfides, whereas in the Zr-killed steel, the inclusion structure consisted of mainly fine spherical oxide inclusions with sulphide shells. The impurity content did not have a significant effect on the number density of inclusions, as with higher and lower impurity content, the number of inclusions was 83.7 and 78.8 mm−2, respectively. However, the size distribution of the inclusions, especially the coarse inclusions with their longest length greater than 8 µm, differs much from each other. The number density of coarse inclusions differs from 0.8 to 1.1 mm−2 with processing, and in Al-killed steel, 55.5% of the coarse inclusions were titanium nitrides or manganese sulfides, whereas in Zr-killed steel, only 22.5% of the coarse inclusions were titanium nitrides and manganese sulfides. Coarse titanium nitrides were especially detrimental to the impact toughness. The number density of them should be below 0.33 mm−2 in order to guarantee the best possible toughness in the steel in question. The average crystallographic grain size detected by electron backscattered diffraction of Zr-killed steel (4.28 ± 2.70 μm) was smaller than that of Al-killed steel (6.00 ± 4.80 μm). As a result from the grain refinement and sulphide shape control, Zr-killed steel exhibited superior impact toughness (223 ± 70 J) at − 80 °C as compared with Al-killed steel (153 ± 68 J). Thus, Zr-killed steel was observed to provide good performance in terms of mechanical properties as compared with Al-killed steel.
      PubDate: 2021-01-08
       
  • Microstructure and mechanical properties in core of a carburizing
           20CrNi2MoV bearing steel subjected to cryogenic treatment
    • Abstract: Abstract Microstructure and mechanical properties in core of a carburizing 20CrNi2MoV bearing steel subjected to cryogenic treatment were investigated. Conventional treatment sample was quenched and tempered at 180 °C for 2 h. Cryogenic treatment samples were quenched, cryogenically treated at − 80 and − 196 °C for 4 h, slowly returned to room temperature and thereafter tempered at 180 °C for 2 h, and finally tempered at 180 °C for 2 h. The scanning electron microscope, electron backscattering diffraction, X-ray diffraction and transmission electron microscope were adopted for microstructure characterization. The results show that cryogenic treatment increases the fraction of high-angle grain boundaries and the precipitation of finely dispersed carbides in the matrix, decreases the volume fraction of inter-lath retained austenite, and hence improves the strength and hardness. Compared with the conventional treatment, the hardness, yield strength and ultimate tensile strength of the steel after cryogenic treatment are increased by 11.7%, 12.6% and 18.3%, respectively, while the impact energy is decreased by 9.8%.
      PubDate: 2021-01-07
       
  • Comparison of microstructure and heat treatment distortion of gear steels
           with and without Nb addition
    • Abstract: Abstract In order to research the effect of microalloying Nb, the microstructure and heat treatment distortion of case carburizing steels with and without Nb addition are compared. Results show that a uniform and fine prior austenite grain size was obtained for the steel with the addition of 0.03 wt.% Nb even after being carburized at 980 °C for 37 h, resulting in a very deep hardened layer of about 4 mm. Nb is an effective microalloying element to hinder austenite grain growth of gears during high-temperature carburizing. Theoretical calculation and experimental observation of NbC precipitates indicate that fine NbC precipitates have not evidently dissolved at 980 °C, and thus they can act as grain refiners due to pinning effect. Heat treatment distortion of Nb-added steel is much lower than that of the steel without Nb addition. It may be contributed to its fine and uniform grain size, which presumably influences stress during martensitic transformation.
      PubDate: 2021-01-07
       
  • Tuning Cr-rich nanoprecipitation and heterogeneous structure in equiatomic
           CrFeNi medium-entropy stainless alloys
    • Abstract: Abstract High-/medium-entropy stainless alloys (HESAs/MESAs) are a new kind of alloys with great potential to combine excellent properties from high-/medium-entropy alloys (HEAs/MEAs) and stainless steels. A CrFeNi MESA was chosen to investigate its microstructures and mechanical behaviors. After homogenization, the strength and ductility of CrFeNi MESAs with single-phase face-centered-cubic (fcc) structure were higher compared with those of Fe100−x–yCrxNiy austenitic stainless steels. Cr-rich body-centered-cubic (bcc) precipitates and heterogeneous structure were introduced by cold rolling and annealing at 800 °C. Rolling at 700 °C results in higher dislocation density and the occurrence of lamellar Cr-rich bcc precipitates. High-density dislocations and fcc grains with heterogeneous structure, together with Cr-rich bcc precipitates, contribute to a yield strength improvement of about 50 MPa, and appreciable tensile yield strength of ~ 540 MPa and fracture strain of ~ 20% are obtained. It reveals that not only compositional variations but also grain size and phase structure tuning can be utilized for achieving desired mechanical properties.
      PubDate: 2021-01-07
       
  • Modification for prediction model of austenite grain size at surface of
           microalloyed steel slabs based on in situ observation
    • Abstract: Abstract The initial solidification process of microalloyed steels was simulated using a confocal scanning laser microscope, and the growth behavior of austenite grain was observed in situ. The method for measuring the initial austenite grain size was studied, and the M 0 * (the parameter to describe the grain boundary migration) values at different cooling rates were then calculated using the initial austenite grain size and the final grain size. Next, a newly modified model for predicting the austenite grain size was established by introducing the relationship between M 0 * and the cooling rate, and the value calculated from the modified model closely corresponds to the measured value, with average relative error being less than 5%. Further, the relationship between Tγ (the starting temperature for austenite grain growth) and equivalent carbon content CP (CP > 0.18%) was obtained by in situ observation, and it was introduced into the modified model, which expanded the application scope of the model. Taking the continuous casting slab produced by a steel plant as the experimental object, the modified austenite grain size prediction model was used to predict the austenite grain size at different depths of oscillation mark on the surface of slab, and the predicted value was in good agreement with the actual measured value.
      PubDate: 2021-01-05
       
  • Effect of process parameters on dry centrifugal granulation of molten slag
           by a rotary disk atomizer
    • Abstract: Abstract Dry centrifugal granulation (DCG) experiments for blast furnace slag (BFS) were performed by means of a rotary disk atomizer since water quenching method can create a series of problems. The results showed that the DCG method can granulate the BFS, but the results are easily affected by the slag flow rate, disk rotating speed, disk radius, disk material and slag falling height. The granulating parameters with an excessive flow rate, low rotating speed, SiN–SiC disk, stainless steel disk and low slag falling height are detrimental to the granulation process. The most suitable parameters for granulation are a slag flow rate of 5.1 × 10−5 m3/s, a disk rotating speed of 1500–2300 r/min, a slag falling height of 0.8 m and a smooth graphitic disk with the radius of 0.1 m. In the absence of an off-center flow, the overall best granulating effect produces round particles with mean diameter of 3.43 mm without creating slag fiber. The vitreous content of the BFS particles granulated by graphite disks is 92%, which meets the requirements of cement raw materials. The Bond work index of dry granulated BFS is 18.4 kWh/t, and the grindability of dry granulated slag and water-quenched slag is similar.
      PubDate: 2021-01-04
       
  • Growth mechanism for zinc coatings deposited by vacuum thermal evaporation
    • Abstract: Abstract The vacuum thermal evaporation technique was used to simultaneously deposit zinc coatings onto interstitial free steel plates and single-crystal silicon wafers in a high vacuum environment. The effect of substrate temperature on the morphology and crystal orientation of zinc coatings was investigated. When the substrate temperature was 25 and 50 °C, the zinc crystallites were plate-like and grew under a particular angle to the substrate surface. After the substrate was heated to 100 °C, the zinc crystallites were regular hexagonal and arranged almost parallel to the substrate surface. In addition, observation of pure zinc coatings with different thicknesses showed that the growth of zinc coating was mainly in the Volmer–Weber mode. When the process parameters were appropriate, the zinc coating was composed of closely arranged columnar crystallites, and the crystallites grew preferentially along [0001] direction.
      PubDate: 2021-01-04
       
  • Torsional deformation-induced gradient hierarchical structure in a 304
           stainless steel
    • Abstract: Abstract After applying torsion to cylindrical 304 stainless steel samples, a gradient structure along the radial direction was obtained. It was found that the volume fraction of α′-martensite increased gradually from the center to the surface of samples. The possibility of deformation-induced martensitic transformation was analyzed theoretically, whose conclusions were consistent with the experimental results. It was found that torsional deformation could produce abundant deformation twin and deformation-induced martensite, which could affect the tensile property of steel distinctly. The existence of deformation and martensite during torsion could increase the strength but deteriorate the ductility dramatically during the tensile test, which should be attributed to the weakening of work hardening ability. As a result of severe deformation, both strain-induced and stress-induced martensite have been observed. Also, two types of martensitic transformation mechanisms during torsional deformation were discussed.
      PubDate: 2021-01-04
       
  • Effect of aluminum on secondary recrystallization texture and magnetic
           properties of grain-oriented silicon steel
    • Abstract: Abstract The slab low-temperature reheating grain-oriented silicon steel was prepared in the laboratory, and the high-temperature annealing interruption tests were carried out. The effects of aluminum (which meant acid-soluble aluminum) on the grain size texture, precipitate, magnetic properties and their correlations were studied. The results showed that with the increase in aluminum element, the grain size decreased, while the intensity of {114}<481> and {111}<112> textures increased in the primary recrystallization structure. Meanwhile, the pinning force during the secondary recrystallization and the onset secondary recrystallization temperature were increased. The precipitates were concluded to have a more important role on determining the onset secondary recrystallization temperature than the primary grain size. The higher onset temperature resulted in sharper Goss texture and the better magnetic properties, but when the aluminum content came up to a certain extent, a fine-grain structure was developed. The most suitable aluminum content for present study was 0.025 wt.%, while the onset secondary recrystallization temperature and the primary texture were considered to be conducive to the sharpness of Goss texture.
      PubDate: 2021-01-04
       
  • M 23 C 6 precipitation and Si segregation promoted by deep cryogenic
           treatment aggravating pitting corrosion of supermartensitic stainless
           steel
    • Abstract: Abstract The microstructure evolution and the pitting corrosion resistance of a supermartensitic stainless steel after deep cryogenic treatment process were clarified through X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy (TEM) and electrochemical methods. The results showed that the microstructure of supermartensitic stainless steel mainly consisted of reversed austenite, tempered martensite, and M23C6 carbides after tempering. The deep cryogenic treatment promoted the refinement of the martensite laths and the precipitation of the carbides in comparison with the traditional process. TEM analysis indicated that the segregation of Si atoms at the boundary was found at the interface between carbide and martensite. The pitting corrosion potential of the specimens subjected to deep cryogenic treatment decreased with the elevated tempering temperature, and the lowest pitting corrosion potential was found at the tempering temperature of 650 °C. The sensitivity of the pitting corrosion potential was attributed to the precipitation of M23C6 carbides and Si atoms segregation. Si atoms segregation engendered the formation of Cr-depleted zone near M23C6 and impeded the recovery of Cr-depleted zone.
      PubDate: 2021-01-03
       
  • Composition and processing of direct-quench hot rolled steels with
           ultrahigh strength exceeding GPa
    • Abstract: Abstract The design of high-strength steel has long been discussed in the field of metal structural materials. To further increase the strength of common high-strength steel and further decrease the cost for production, three direct-quench hot rolled steels were designed and fabricated. The rolling and coiling processes were set based on continuous cooling transformation curves. In addition, the effect of the coiling temperature on the tensile properties was discussed to further guide the optimization of the process. It was found that compared with granular bainite, lower bainite probably has more advantages for both the strength and low temperature impact toughness of direct-quench hot rolled steels. Through a process of tailoring the morphology of bainite and controlling the grain boundary precipitation, the newly designed direct-quench hot rolled steels showed greatly improved strength and acceptable ductility/toughness compared with traditional quenched and tempered steels.
      PubDate: 2021-01-03
       
  • Correction to: Separation and enrichment mechanism of C54–TiSi 2 from
           hypoeutectic Ti–65 wt.% Si alloy during directional solidification via
           alternating electromagnetic fields
    • Abstract: The original version of this article unfortunately contained a mistake. Figure 7 was incorrect. The corrected figure is given below.
      PubDate: 2021-01-01
       
  • Role of carbon in modifying solidification and microstructure of a
           Ni-based superalloy with high Al and Ti contents
    • Abstract: Abstract The effect of carbon ranging from 0.014 to 0.071 wt.% on the solidification and microstructure of a Ni-based superalloy with high Al and Ti contents was studied. The results show that the increase in carbon addition significantly increases the size and volume fraction of MC carbides and promotes the change of their morphology from blocky to elongated shape. However, the carbon addition obviously decreases the size and volume fraction of eutectic (γ + γ′) and reduces η phase and borides formation. The change in carbide characteristics is mainly because of the increasing carbide-forming element and carbides precipitation temperature with the increase in carbon which favors the growth of them along the interdendritic liquid film. MC carbides are formed at an earlier solidification stage than the eutectic (γ + γ′). The increased carbide formation consumes more Ti, which delays and reduces the eutectic (γ + γ′) precipitation. The delay of eutectic (γ + γ′) precipitation leads to a deeper undercooling, which significantly decreases the critical Ti concentration for its precipitation. This, in turn, lowers Ti/Al ratio in residual liquids ahead of the eutectic (γ + γ′) and hence reduces η formation subsequently. B and Zr are slightly enriched in the carbides, which are considered during discussing how carbon influences the eutectic (γ + γ′) precipitation.
      PubDate: 2021-01-01
       
  • Metadynamic recrystallization behaviors of SA508Gr.4N reactor pressure
           vessel steel during hot compressive deformation
    • Abstract: Abstract The metadynamic recrystallization (MDRX) model is established, and the coefficients determined by multiple linear regression analysis are used to describe the microstructure evolution of SA508Gr.4N steel. The effects of compression temperature of 950–1150 °C, strain rate of 0.001–0.1 s−1, pre-strain of 0.3–0.6, initial austenite grain size (IAGS) of 136–552 μm, and interval time of 1–300 s on the MDRX kinetics and microstructure evolution were analyzed, using two-pass compression test method on Gleeble thermo-mechanical simulator. The results show that MDRX kinetics and austenite grain size are strongly dependent on compression temperature and strain rate, MDRX volume fraction increases with increasing compression temperature and strain rate, and the grain size decreases with increasing strain rate and decreasing compression temperature, while less affected by the pre-strain and IAGS. Meanwhile, the values predicted using MDRX model and the ones calculated from experiment are compared, and the results show that the proposed model can give a reasonable estimate of MDRX behavior for SA508Gr.4N steel.
      PubDate: 2021-01-01
       
  • Ratcheting behavior of notched stainless steel samples subjected to
           asymmetric loading cycles
    • Abstract: Abstract The ratcheting response of 316 stainless steel samples at the vicinity of notch roots under single- and multi-step loading conditions is evaluated. Multi-step tests were conducted to examine local ratcheting at different low–high–high and high–low–low loading sequences. The stress levels over loading steps and their sequences highly influenced ratcheting magnitude and rate. The change of stress level from low to high promoted ratcheting over proceeding cycles while ratcheting strains dropped in magnitude for opposing sequence where stress level dropped from high to low. Local ratcheting strain values at the vicinity of notch root were found noticeably larger than nominal ratcheting values measured at farer distances from notch edge through use of strain gauges. Ratcheting values in both mediums of local and nominal were promoted as notch diameter increased. To assess progressive ratcheting response and stress relaxation concurrently, the Ahmadzadeh-Varvani (A-V) kinematic hardening rule was coupled with Neuber’s rule enabling to calculate local stress at notch root of steel samples. Local stress/strain values were progressed at notch root over applied asymmetric stress cycles resulting in ratcheting buildup through A-V model. The relaxation of stress values at a given peak-valley strain event was governed through the Neuber’s rule. Experimental ratcheting data were found agreeable with those predicted through the coupled framework.
      PubDate: 2021-01-01
       
  • Printability and physical properties of iron slag powder composites using
           material extrusion-based 3D printing
    • Abstract: Abstract There have been many studies on three-dimensional (3D) printing using metal compounds. However, 3D printing using a metal compound has disadvantages in that it increases the cost for supplying metal materials. A method of using slag which is a recyclable material has been proposed to reduce costs. With the growing demand for additive manufacturing using by-products, slag has gained attention as a diverse recycling material for 3D printing technologies. A new fabrication approach was analyzed for producing porous bodies via additive manufacturing for blending slag and reinforced metals. However, because of its low quality due to low strength, low durability, and structural defeats, the amount of slag generated is high, and its usability remains uncertain. Also, slag is an excellent material with a huge potential for producing structures with high mechanical properties, and limited research in the area of slag recycling has been conducted due to difficulties in sintering the iron by-products. To develop a recycling approach that utilizes slag in 3D printing powders, a study to increase the industrial usability by mixing slag and ceramic beads was described. A method was presented to compare the physical properties of 3D printed slag parts with the physical properties of those generated by blending iron slag, alumina, and zirconia. In order to find the mixing ratio with the optimum physical properties, the average particle size, bending stress, and maximum compressive stress were tested. The combination ratio to obtain the highest strength was when iron slag powder was 40% and alumina was 60%. In addition, the specimens by composition to which the stress test was applied were cut to analyze the tissue under a microscope. It is thought that cracking in the sintered structure decreases and density increases by mixing alumina and zirconium, contributing to increased strength. When a ceramic bead composed of alumina and zirconium is mixed with slag to form a composite material, a metal compound having a level of physical properties that can be used as a material for 3D printing can be produced. Furthermore, a novel concept of producing lightweight structural materials via additive manufacturing, which entails a fabrication process whereby high-strength metals are stacked inside hollow base steels, was proposed.
      PubDate: 2021-01-01
       
 
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