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Copyright of Steel Pipe is the property of Steel Pipe Magazine 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 Steel Pipe is the property of Steel Pipe Magazine 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.)

In order to investigate the influence of gradual stress relieving treatment on the microstructure, texture evolution, grain structure, and misorientation distribution of the hot-rolled Ti6Al4V–5Cu (α+β) alloy deformed in various thickness reduction ratios (TRR's) of 15%, 58%, and 73% to maintain the burger orientation relationship (BOR), different stress reliving treatment was specially designed for relieving the residual stresses occurred due to the hot deformation process. Using IPF maps, the majority of the α grains, specifically the elongated ones were found nearly at 45 ° with respect to the rolling and transverse direction. The study also show that the heat treatment schedule on the 58% deformed alloy significantly promote the transformation of β to α phase and a special microstructure with an equiaxed grains is produced. The local misorientation angle distribution due to stress reliving treatment has also discussed. Using EBSD analysis, the alloy processed under highest TRR's (i.e., 73%) and subsequent stress relieving treatment could result a serious internal crystalline instability with various degree of element diffusion rate, which promote a severe and ease of alloy coarsening. Thus, coarsening encourage the formation of grains with the highest softening potential, comparatively. It is obvious that the stress-relived treatment does not result a change in microstructure. However the internal residual stresses on the hot deformation were relieved, the texture intensity had increased quietly. A significant textural behavior could be achieved on the 73% hot-rolled alloys by the stress-relieving process to align the α/β fiber texture interface in parallel coincidence to maintain the BOR.

In this work, a two-stage rolling method with varied temperature and strain rate was proposed for powder metallurgy (PM) Ti–47Al–2Cr–2Nb-0.2W alloy sheets based on the guidance of processing map and microstructure evolution. Compared with conventional rolling at a high temperature and a low strain rate, the TiAl alloy exhibited enhanced plastic deformability through the implementation of the two-stage rolling method, resulting in a higher cumulative true strain. Microstructure analysis revealed significant grain refinement in the rolled sheet. During the first stage of hot rolling with high temperatures and low strain rates, the softening behavior caused by dynamic recovery (DRV) and dynamic recrystallization (DRX) is conducive to the plastic deformation in the second stage rolling (low temperatures and high strain rates). In addition, the formation of mechanical twins further promotes DRX behavior. The softening mechanism of α2 phase is DRV, and that of γ phase is continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX).

Copyright of Steel Pipe is the property of Steel Pipe Magazine 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.)

The “Gold Dust Defect” that sometimes appears on the surface of the AISI 430 ferritic stainless steel has been related to an improper recrystallization of the material. Hot-rolling, a decisive step in the production process, seems the step where this defect is induced and temperature during this treatment plays a key role. To trace back the origin of this defect, the microstructural evolution of a sample of an AISI 430 was monitored at the different stages in the production process of the steel. In particular, a detailed study combining electron backscatter diffraction with other techniques, such as optical microscopy and scanning electron microscopy has been performed. The whole set of results evidences that after hot-rolling and subsequent annealing, the material contains a large amount of martensite in the center of the cross-section due to a fast cooling of the austenite originated during rolling. In addition, the surface shows a top-layer made up by unrecrystallized subgrains separated from the matrix by an accumulation of chromium carbides. After pickling, the top-layer of subgrains semi-detaches from the surface forming flakes which cannot recrystallize. Most of these flakes do not peel off during the subsequent stages but survive until the end of the production process, forming Gold Dust Defect flakes.

Copyright of Steel Pipe is the property of Steel Pipe Magazine 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.)

Austenitic stainless steels are prone to mixed grain structure (MGS) defect during solution treatment or hot work. We demonstrate that strain–induced continuous M23C6 precipitates at grain boundaries (GBs) enable obtaining uniform deformed structures through hot–rolling at 1000 °C and 1100 °C. After solution treatment of the hot–rolled specimens at 1200 °C for 10–60 min, static recrystallization occurs. After the solution time exceeds 10 min, the M23C6 precipitates at GBs dissolve completely. The recrystallized grains grow normally as the solution time increase, and there is no abnormal grain growth. Strain–reduced the M23C6 precipitation can pin GBs during the dissolution process, thereby eliminating MGS defect.

Grain size distribution after the completion of a phase transformation was studied through the laboratory-controlled hot-plastic deformation of dual phase 600 (DP 600) steel using a specially prepared asymmetric single-pass hot-rolling wedge test with a refined reheating grain size instead of the usual coarse-grained starting microstructure observed in practice. The experiment was performed to reduce generally needed experimental trials to observe the microstructure development at elevated temperatures, where stable and unstable conditions could be observed as in the industrial hot-rolling practice. For this purpose, experimental stress–strain curves and softening behaviors were used concerning FEM simulations to reproduce in situ hot-rolling conditions to interpret the grain size distribution. The presented study revealed that the usual approach found in the literature for microstructure investigation and evolution with a hot-rolling wedge test was deficient concerning the observed field of interest. The degree of potential error concerning the implemented deformation per notch position, as well as the stress–strain rate and related mean flow stresses, were highly related to the geometry of the specimen and the material behavior itself, which could be defined by the actual hardening and softening kinetics (recrystallization and grain growth at elevated temperatures and longer interpass times). The grain size distribution at 1100–1070 °C was observed up to a 3.45 s−1 strain rate and, based on its stable forming behavior according to the FEM simulations and the optimal refined grain size, the optimal deformation was positioned between e = 0.2 and e = 0.5. [ABSTRACT FROM AUTHOR]

Ti/Al multilayered composites (LMCs) with 3-layers, 5-layers and 7-layers were prepared by hot‐pressing and hot‐rolling. The effects of the interface on the mechanical properties and stamping formability of LMCs were revealed. The results indicate that the TiAl3 phases at the interface thicken gradually with the increase of layers. As the layers of LMCs increases, both the grain size and the basal texture strength of Ti decrease, and Ti possesses a higher Schmid factors (SF) and more uniform SF distribution, which promotes the overall coordinated deformation of LMCs. The elongation (EL) of LMCs gradually increases at the expense of the strength with the increase of layers. The stress–strain transfer across the interface, the release of residual stress through interfacial microcracks, and the improvement of the interfacial metallurgical bonding strength are all conducive to the coordinated deformation between Ti and Al layers, thus the strength of LMCs decreases and the EL enhances. Both the yield strength ratio (σs/σb) and plastic strain ratio (r) decrease, while the strain-hardening exponent (n) increases with the increase of layers of LMCs, which are beneficial to improve the stamping formability of LMCs. The number of interface increases with the increase of layers, which hinders crack propagation. Moreover, the microcracks are easily induced by the brittle TiAl3 phase at the interface, and the main cracks deflect obviously and release part energy in the form of secondary microcracks, thus delaying the failure of LMCs and improving their stamping formability. [ABSTRACT FROM AUTHOR]

Laminated metal composites have attracted more attention due to their ultra-high strength, fracture toughness and elongation, full considerations of each component, and coordinated deformation effect between interfaces. Herein, Zn and Al were selected as the component materials to prepare Al/Zn laminated composite plates using hot rolling and low temperature annealing, and studied the influence of the thickness of the diffusion layer at the interface to understand the reason for the strengthening and toughening mechanism. The results show that, with an increase in annealing temperature and time, the grain will recover and recrystallize to grow. A diffusion layer with a certain thickness formed at the interface due to the mutual diffusion of Al and Zn atoms at the interface. As annealing time and temperature increase, the yield and tensile strengths first increased and then decreased. The tensile fracture morphology showeds many deep dimples. In the rolling state, the micro-hardness value at the interface was between Al and Zn. [ABSTRACT FROM AUTHOR]

The processes of rolling and annealing of explosively welded multi-layered plates significantly affect the functional properties of the composite. In current research, fifteen-layered composite plates were fabricated using a single-shot explosive welding technique. The composites were then rolled up to 72% to reduce layer thickness, followed by annealing at 625 °C for varying times up to 100 h. Microstructure evolution and chemical composition changes were investigated using scanning electron microscopy equipped with energy-dispersive spectroscopy. The mechanical properties of the composite were evaluated by tensile testing, while the strengths of individual layers near the interface were evaluated by micro-hardness measurements. After explosive welding, the wavy interfaces were always formed between the top layers of the composite and the wave parameters decreasing as the bottom layers approach. Due to the rolling process, the thickness of Ti and Al layers decreases, and the waviness of top interfaces disappeared. Simultaneously, the necking and fracture of some Ti layers were observed. During annealing, the thickness of layers with chemical composition corresponding to the Al3Ti phase increased with annealing time. A study of growth kinetic shows that growth is controlled by chemical reaction and diffusion. The results of micro-hardness tests showed that after annealing, a fourfold increase of hardness can be observed in the reaction layers in relation to the Ti, while in relation to Al, the increase of hardness is even 15 times greater. [ABSTRACT FROM AUTHOR]

A novel method of compound casting with hot-rolling to prepare foamable precursor sandwich (FPS) is proposed in this paper, and aluminum foam sandwich (AFS) was obtained by subsequent foaming. The cores and interfaces of FPSs and AFSs made with different rolling passes were investigated. The results indicate that increase of the rolling pass can improve the foaming capacity of FPS, cell uniformity and interface bonding quality of AFS. The differences in load resistance and energy absorption of AFSs made with different rolling passes were compared under three-point bending tests. It is found that the deformation uniformity of core cells increases but the overall load resistance and energy absorption of AFS decrease with the rolling pass. The evaluation of facesheet/core interface effect on the load resistance and energy absorption of AFS showed increasing the facesheet thickness and rolling pass is a good way to enhance the load resistance and energy absorption for AFS. [ABSTRACT FROM AUTHOR]

In this present paper, a biodegradable Zn- x Cu alloys with an ultrahigh strength and ductility can be achieved via hot-rolling and tailoring Cu concentration, and the role of Cu concentration on the microstructure and texture evolution in the Zn- x Cu alloys during hot-rolling were investigated by XRD, EBSD and TEM analysis. The results show that the microstructure of as-cast Zn- x Cu alloys consisted of large sized CuZn 5 phase and Zn matrix grains before hot-rolling, and numerous submicron CuZn 5 phase can dynamically precipitate during hot-rolling of Zn- x Cu alloys. The existence of CuZn 5 phase can result in the particle stimulated nucleation of recrystallization (PSN), and then result in the formation of fine recrystallized grains. Moreover, three texture components including 0001 < 11 2 ¯ 0 > , 10 1 ¯ 1 < 1 ¯ 012 > and 11 2 ¯ 0 < 0001 > textures can form in the Zn- x Cu alloys after hot-rolling. With boosting Cu concentration, the intensity of 11 2 ¯ 0 < 0001 > texture gradually reduced, while the intensity of 0001 < 11 2 ¯ 0 > and 10 1 ¯ 1 < 1 ¯ 012 > texture components firstly raised with the augment of Cu concentration, and then reduced. For the Zn- x Cu alloys with 8 wt%Cu concentration, a combination of high yield strength, ultimate tensile strength and elongation (269.7 MPa, 322.9 MPa and 26.3 %) can be achieved, which can meet the high-performance demands of biodegradable metal vascular stents. • Biodegradable Zn Cu alloy with ultrahigh strength and ductility was achieved via tailoring Cu concentration. • Role of Cu concentration on microstructure and texture evolution was investigated. • High strength and ductility was mainly associated with grain refinement and precipitation strengthening. [ABSTRACT FROM AUTHOR]

For a wide industrial application of magnesium alloys, a method for imparting high damping properties while maintaining mechanical properties is required. Controlling the crystallographic texture seems to be useful, because dislocations are known to have a significant influence on the damping characteristics of magnesium alloys. In addition, textures are affected by the microstructure and texture variation when the deformation or annealing is applied. However, there were less reports about their effect on damping capacity. Therefore, the effect of twinning and annealing, which can affect the recrystallization, were investigated in this study. An AZ31 alloy was hot rolled at 673 K with a reduction ratio of 10% and 50%, and then annealed at 673 K and 723 K for 0.5, 1, 2, and 3 h, respectively. SEM-EBSD was used to examine the microstructure and texture. In addition, each specimen's hardness and internal friction were contemporarily measured. As a result, hot rolling produced tensile twins and their fraction increased with internal friction when the reduction ratio increased. Due to annealing, a discontinuous type of static recrystallization occurred within the twinning grains, and was highly activated along with the increasing annealing temperature and the fraction of twinning. In the samples annealed at 723 K, the internal friction continuously increased over the annealing time, whereas in the samples annealed at 673 K, the decrease in dislocation density was delayed while the internal friction showed a relatively low value. [ABSTRACT FROM AUTHOR]

Copyright of Steel Pipe is the property of Steel Pipe Magazine 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.)

The effects of post-processing heat treatments on hot-rolled Ti–6Al–4V with extra low interstitial concentration were investigated. The 2 mm sheets were rolled in the single β phase field region and subsequently cooled in air. A continuous cooling transformation (CCT) diagram was generated, revealing the strong influence of the cooling rate on both microstructure and hardness. Cooling rates between 0.01 and 200°C s−1 were selected. While rapid cooling resulted in a martensitic transformation β → α′, a decrease in the cooling rate led to a progressive spheroidization of the lamellar (α + β) microstructure. With a focus on the established CCT continuous cooling transformation diagram, this study contains insight on the microstructure evolution of the Ti–6Al–4V ELI alloy during cooling from the single β phase field region. [ABSTRACT FROM AUTHOR]

The effect of initial hot‐rolling temperature on microstructure, texture, and formability of Al–Mg–Si alloy sheets is investigated using scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), and tensile test. The results indicate that the textures of the sheet after hot‐rolling comprise most of Copper {112}<111>, Brass {011}<211>, and S {123}<634>. Initial rolling temperature affects the particles distribution before solution treatment, thereby further influencing the recrystallized microstructure and texture after T4P treatment. After T4P treatment, Cube {001}<100> component is the main grain orientation in the sheet with an initial rolling temperature of 530 °C. While CubeND {001}<310> orientation forms after other three initial rolling temperatures (450, 500, and 555 °C). However, the grain orientation distribution is more dispersed with an initial rolling temperature of 555 °C. Within the initial rolling temperature range from 530 to 555 °C, the average plastic strain ratio r value of the sheet is relatively higher. The anisotropy Δr value at an initial rolling temperature of 555 °C is the closest to zero. Therefore, the initial rolling temperature of 555 °C is the most conducive to improving the formability of the alloy sheet. [ABSTRACT FROM AUTHOR]

The mechanical properties and precipitation behavior of hot-rolled microalloyed steels with varied Nb and V additions were investigated. The steels had a predominantly ferritic microstructure with a very good combination of strength (σUTS = 800–1000 MPa), ductility (total elongation = 16–19%) and hole expansion ratio (32–34%). The strength increased with increasing Nb and V content. The stretch-flangeability of the steels did not deteriorate with increasing strength. The favorable hole expansion behavior of the steels is attributed to the fine ferrite grain size (1.6–1.8 μm) and uniformity of the microstructure, as well as the fine precipitates of Nb and V carbonitrides in the matrix. Nb carbonitrides formed during hot rolling and contributed to the grain refinement through their interaction with recrystallization. The co-precipitation of Nb and V carbonitrides during coiling was confirmed and characterized by 3D atom probe tomography. The formation of these fine precipitates contributed to further increase in the strength of the V-containing steel allowing the steel to achieve strength >1000 MPa.

Grain size distribution after the completion of a phase transformation was studied through the laboratory-controlled hot-plastic deformation of dual phase 600 (DP 600) steel using a specially prepared asymmetric single-pass hot-rolling wedge test with a refined reheating grain size instead of the usual coarse-grained starting microstructure observed in practice. The experiment was performed to reduce generally needed experimental trials to observe the microstructure development at elevated temperatures, where stable and unstable conditions could be observed as in the industrial hot-rolling practice. For this purpose, experimental stress–strain curves and softening behaviors were used concerning FEM simulations to reproduce in situ hot-rolling conditions to interpret the grain size distribution. The presented study revealed that the usual approach found in the literature for microstructure investigation and evolution with a hot-rolling wedge test was deficient concerning the observed field of interest. The degree of potential error concerning the implemented deformation per notch position, as well as the stress–strain rate and related mean flow stresses, were highly related to the geometry of the specimen and the material behavior itself, which could be defined by the actual hardening and softening kinetics (recrystallization and grain growth at elevated temperatures and longer interpass times). The grain size distribution at 1100–1070 °C was observed up to a 3.45 s−1 strain rate and, based on its stable forming behavior according to the FEM simulations and the optimal refined grain size, the optimal deformation was positioned between e = 0.2 and e = 0.5.

Zn, a biodegradable metal, exhibits immense capability as a bioresorbable implant material because of its remarkable biocompatibility and stronger corrosion resistance than Mg. Nonetheless, Zn's limited mechanical strength and hardness have significantly hindered its widespread implementation. This study aimed to strengthen the mechanical, degradation resistance, and biocompatibility of zinc composites by rolling them and investigating the impact of Mn content on the material properties of Zn composites. The prepared hot rolled Zn-1.5Mg-0.5HA(hydroxyapatite)-1.5Mn (ZMR2) sample shows enhanced Ultimate tensile strength (UTS 209 MPa) and hardness (103 HV). In a PBS solution, the degradation rates of the hot-rolled sample show a consistent reduction as the content of Mn increases, reaching a rate of 0.032 mm/year. Furthermore, excellent hemocompatibility was observed for both the cast and rolled specimens. However, the rolled ZMR2 sample exhibited the lowest value (4.5 %) among the two. The cultured MG63 cells demonstrated high viability when exposed to diluted extracts (25 % and 50 % extract) of the HR ZMR2 sample from Day 1 to Day 5. In both cases, the viability exceeded 80 %, indicating the absence of any potential cytotoxic effects. [Display omitted] • The stir casting method has successfully reinforced a zinc matrix with magnesium, manganese, and hydroxyapatite (HA). • Hot rolling successfully enhanced the mechanical properties, making the composite suitable for implant applications. • The corrosion rate of hot rolled ZMR2 sample has been reduced to 0.742 mm/year. • The hemolysis percentage for the hot rolled ZMR2 sample has been reduced to 4.5 %. • The cell viability of the hot rolled ZMR2 sample, using a 25 % extract, exceeds 95 % on both Day 1 and Day 3. [ABSTRACT FROM AUTHOR]

In order to improve the prediction accuracy of the rolling force Self-learning Model and change the phenomenon that the learning coefficient is unstable and the optimization process is not reasonable due to the experience value of the self-learning factor in the traditional self-learning, this paper proposes an improved adaptive differential evolution (IADE) algorithm based on the standard differential evolution algorithm to solve and optimize the problem quickly. The prediction accuracy of rolling force model is improved. The experimental results show that the prediction accuracy of IADE algorithm is lower than that of the traditional model, which can effectively improve the prediction accuracy.

Pure zinc has excellent biocompatibility and acceptable bio-degradation rate. But it has low mechanical strength and becomes brittle at elevated temperature. This problem can be eliminated with zinc base metal matrix composites. Keeping in view, this paper presents the fabrication process of bioabsorbable hybrid Zn/(Ag + Fe + Mg) metal matrix composite (MMC). The ultrasonic vibration-assisted stir casting technique with argon atmosphere was used to fabricate the bioabsorbable hybrid Zn/(Ag + Fe + Mg) MMC. An ultrasonic vibration-assisted stir casting set-up has been developed and utilized for the purpose. Mechanical property testing on fabricated composite specimens was carried out, and the effects of particulate reinforcement on mechanical properties were investigated. The mechanical properties of fabricated stir cast composite were modified and improved by hot-rolling and solution heat-treatment processes. From test results, it is found that the ultimate tensile strength (UTS) of the cast hot-rolled composite was 361.88 MPa, and hot-rolled with solution heat-treated composite was 284.31 MPa, whereas cast zinc was only 33.6 MPa. Hence, test results reveal the significant improvement in the UTS of the fabricated hybrid cast Zn/(Ag + Fe + Mg) MMC over cast Zn matrix. The hot-rolled and solution heat-treated hybrid Zn/(Ag + Fe + Mg) MMC may be used as an alternative material for fabrication of bioabsorbable medical implants. [ABSTRACT FROM AUTHOR]

The effects of Ag content and hot-rolling on the microstructure and mechanical properties of Zn-1.5Cu-xAg-0.1Zr(x = 0, 0.1, 0.5, 1.0) alloys were investigated. The microstructure, phase composition and fracture morphology of the alloys were observed and analyzed by optical microscope, x-ray diffraction, scanning electron microscope, energy dispersive spectrometer and universal mechanical testing machine. The results show that Ag has the effect of grain refinement. After alloying, the grain size of as-cast Zn-1.5Cu-xAg-0.1Zr alloy decreased first and then increased, and the minimum grain size of as-cast Zn-1.5Cu-0.5Ag-0.1Zr alloy was refined to 64.18 μm. At the same time, new phase AgZn3 began to precipitate, the yield strength (YS), ultimate tensile strength (UTS), and elongation (EL) of alloys were also up to 97.35 MPa, 139.25 MPa and 7.60%, respectively. After hot-rolling, the grain of Zn-1.5Cu-xAg-0.1Zr alloy was broken and new phase CuZn5 was precipitated. The mechanical properties were significantly improved, and the maximum YS, UTS and EL of as-rolled Zn-1.5Cu-1.0Ag-0.1Zr alloy were 218.14MPa, 244.83MPa, 64.50%, respectively. [ABSTRACT FROM AUTHOR]

Copyright of Steel Pipe is the property of Steel Pipe Magazine 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.)

Mg-(Al-)Ti laminated sheets with large bonding interfaces were prepared by a differential temperature hot-rolling process, in which the preheating treatment of Ti was 25–100 °C higher than that of Mg. The rolled sheets contained different Al layer thicknesses (≤0.05 mm), and the thickness of the diffused region at the interface of 3–7 μm was formed by rolling at 175 °C. The interfaces were the solid-solution regions of Mg(Al) and Ti(Al), and no intermetallic compounds were generated during both the rolling process and annealing treatment. The hardness of the interfaces was 16–30% greater than that of the Mg matrix and Ti matrix. The results of mechanical tests displayed that the Mg-(Al-)Ti sheets exhibited higher strength and elastic modulus compared to those of the rolled AZ31B sheet. Their UTS and YTS were about 223–460 MPa and 303–442 MPa, respectively, with an elongation of 0.04–0.17 and high elastic modulus of 52–68 GPa. The Mg-Ti (containing about 62 at.% Mg) rolled sheet exhibited the most excellent strength. The UTS and YTS were about 460 MPa and 442 MPa, with an elongation of 0.04 and elastic modulus of 61.5 GPa. Additionally, Mg-Ti sheets with thin Ti thickness possessed a higher work-hardening rate (n), as well as hardening rate, than the rolled Mg-Al-Ti sheets. This is because fractured Ti pieces around the interfaces have a significant strengthening effect. This study provides a simple method for fabricating Mg-(Al-)Ti sheets with high elastic modulus. [ABSTRACT FROM AUTHOR]

Laminated metal composites have attracted more attention due to their ultra-high strength, fracture toughness and elongation, full considerations of each component, and coordinated deformation effect between interfaces. Herein, Zn and Al were selected as the component materials to prepare Al/Zn laminated composite plates using hot rolling and low temperature annealing, and studied the influence of the thickness of the diffusion layer at the interface to understand the reason for the strengthening and toughening mechanism. The results show that, with an increase in annealing temperature and time, the grain will recover and recrystallize to grow. A diffusion layer with a certain thickness formed at the interface due to the mutual diffusion of Al and Zn atoms at the interface. As annealing time and temperature increase, the yield and tensile strengths first increased and then decreased. The tensile fracture morphology showeds many deep dimples. In the rolling state, the micro-hardness value at the interface was between Al and Zn.

To further improve the properties of the Al–11.5Si–0.4Fe–0.35Mg, the effects of different reductions of hot-rolling (HR) Al–Si–Fe–Mg alloy on microstructure, thermal conductivity (TC), and mechanical properties were investigated in this paper. The results show that the eutectic silicon phases are broken and moved during the HR process. The average size of eutectic silicon phase decreases. Meanwhile, the aspect ratio of eutectic silicon phase closer to 1 and the distribution of that are more uniform with the increase of HR reduction. In addition, the ternary Al–Fe–Si phases are also broken after HR. It indicates that the action of shear force induced by the HR process is beneficial to promote refinement and spheroidization of the eutectic silicon phase, hence further improves the properties of the alloy. Apparently, the fine and dispersed distribution of spherical silicon particles can minimize the splitting of the α -Al matrix, decrease the scattering effect on free electrons, and increase the number of free-electron transport channel. Therefore, the overall performance of HR Al–Si–Fe–Mg alloy with a reduction of 71.25% is the best with the TC of 170.24 W/m ⋅ K, the tensile strength of 241.98 MPa and elongation of 8.73%, respectively. [ABSTRACT FROM AUTHOR]

FeCrAl alloy is one of the most promising nuclear fuel claddings among many accident tolerant fuel (ATF) materials due to its excellent oxidation resistance and good mechanical properties. However, the effect of process conditions on the creep properties of the FeCrAl alloy is not clear till now. In this study, the impact of a process condition of hot-rolling on the creep properties of FeCrAl alloy was investigated using a nano-indentation creep test under a temperature of 350°C. The microanalysis results indicated that the grain size became smaller with the increase of the hot-rolling thickness reduction. The nano-indentation creep test results showed that the creep power-law stress exponent was about four, and the creep resistance increased when the hot-rolling thickness reduction increased.

In the present work, influence of titanium dioxide (TiO 2) and graphite (Gr) hybrid reinforcement on microstructure and mechanical behavior of Al7075 alloy is studied. Al7075 and its hybrid composite samples were fabricated by using stir-casting and hot rolling technique. Hot rolling was carried out at a temperature of 450 °C with a reduction-ratio of 90%. Microstructure examination showed a good dispersion of titanium dioxide and graphite reinforcement particles with excellent bond with Al7075 matrix alloy. In case of hot rolling, both the reinforcements were found to be aligned in the direction of rolling. The microhardness and tensile strength of hybrid composites were remarkably improved in case of hot rolling compared to that of cast composites. [ABSTRACT FROM AUTHOR]

Copyright of Materials & Technologies / Materiali in Tehnologije is the property of Institute of Metals & Technology 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.)

This paper aims to investigate the microstructural evolution and mechanical properties of hot-deformed AlMg4 alloys with Mn, Fe, and Si as the main impurities. For this purpose, solidification behavior and microstructural evolution during hot-rolling and heat-treatment processes are investigated by using theoretical calculations and experimental characterization. The crystallization and morphological transformation of intermetallic Al3Fe, Al6Mn, and Mg2Si phases are revealed and discussed in terms of the variation in chemical composition. Following a homogenization heat-treatment, the effect of heat treatment on the intermetallic compounds is also investigated after hot-rolling. It was revealed that the Mg2Si phase can be broken into small particles and spherodized more easily than the Al3Fe intermetallic phase during the hot-rolling process. For the Mn containing alloys, both yield and ultimate tensile strength of the hot-rolled alloys increased from 270 to 296 MPa while elongation decreased from 17 to 13%, which can be attributed to Mn-containing intermetallic as well as dispersoid. [ABSTRACT FROM AUTHOR]

We previously reported on commercial 90W7Ni3Fe (90W, wt. %) tungsten heavy alloy (WHA) plates, which were hot-rolled (HR) at 900 °C to thickness reductions of 62 %, 74 % and 87 % (62R, 74R and 87R), and an as-sintered (AS) 90W plate. In contrast to 62R and 74R, the 87R WHA was given a final processing heat treatment (HT) at 1400 °C/3 h (87RHT). HR deforms the WHA microstructure into an anisotropic brick (W) and mortar (NiWFe ductile phase) composite architecture. Fracture toughness tests showed that after the processing HT, the 87RHT plate experienced stable crack growth, with an average elastic-plastic fracture toughness of K Jm ≈ 116 ± 20 MPa√m, somewhat higher than the AS K Jm ≈ 97 ± 18 MPa√m. This compares to elastic fracture toughness of K Im ≈ 35 ± 2 MPa√m in the 62R and 74R conditions, absent a final HT. Here, we report on the microstructures and mechanical properties of four new WHA conditions following an additional recovery anneal at 1300 °C/24 h. The recovery anneal results in similar average elastic-plastic toughness of K Jm ≈ 125 ± 12 MPa√m in all four processing conditions, which is slightly higher than for the AS and 87RHT WHA, and much higher than for the 62R and 74R WHA, without the processing HT. Scanning electron microscopy and electron backscatter diffraction showed that the final 1300 °C/24 h anneal recovers the hardening microstructures in the 62R and 74R WHA. The lower strength promotes crack tip microcracking dilatational shielding, which increases the WHA fracture toughness. The implications of these results to the design of WHA are briefly discussed. [ABSTRACT FROM AUTHOR]

High-entropy alloys (HEAs), characterized by their unique design concept without a distinct major element, offer a versatile alloy design window while ensuring outstanding properties. In this study, the FeCoCrNi–AlTi alloy system, which exploits L1 2 phase with slow ripening kinetics due to the coherent interface with the FCC phase, has been researched to increase strength via precipitation. This system has been widely studied to improve mechanical properties through microstructure optimization, especially in a direction that suppresses discontinuous precipitation while enhancing strength. Herein, we propose a novel processing method utilizing hot-rolling followed by direct aging for a newly designed (FeCoNi) 79.5 Cr 10.5 Al 5 Ti 5 (at%) HEA. The coarse yet strong FCC matrix, generated via hot-rolling, proves advantageous in the subsequent direct aging, as revealed through careful microstructural characterization of both continuous and discontinuous precipitates. A high yield strength of 1065.5 ± 0.4 MPa, a uniform elongation of 14.2 ± 0.0%, and a total elongation of 27.5 ± 0.9% are simultaneously achieved, due to maintaining high dislocation density and promoting continuous precipitation, whereas discontinuous precipitation is suppressed and occupies little area fraction of ∼8%. Careful discussions are provided regarding the impact of the newly proposed processing on the precipitation mechanism, and how the resulting microstructure influences the strengthening mechanisms. This work demonstrates the effectiveness of a simplified thermomechanical process, providing valuable insights into microstructure control in HEAs. [ABSTRACT FROM AUTHOR]

In order to improve the prediction accuracy of the rolling force Self-learning Model and change the phenomenon that the learning coefficient is unstable and the optimization process is not reasonable due to the experience value of the self-learning factor in the traditional self-learning, this paper proposes an improved adaptive differential evolution (IADE) algorithm based on the standard differential evolution algorithm to solve and optimize the problem quickly. The prediction accuracy of rolling force model is improved. The experimental results show that the prediction accuracy of IADE algorithm is lower than that of the traditional model, which can effectively improve the prediction accuracy. [ABSTRACT FROM AUTHOR]

Customized small batch orders and sustainable development requirements pose challenges for product quality control and manufacturing process optimization for steel production. Building a multi-quality objective process parameter optimization method that converts the original single target optimization into multi-objective interval capability optimization has become a new method to ensure product quality qualification rate and reduce production costs. Aiming at the multi-quality objective control problem of plate products, we proposed a novel multi-objective process parameter interval optimization model (MPPIO) with equipment process control capability and parameter sensitive analysis. The multi-output support vector regression method was used to establish a multi-quality objective prediction model, which was settled as a verification model for the process parameter optimization results based on the particle swarm optimization algorithm (PSO). The process control capability functions of key parameters were fitted based on the real data in production. With these functions, each optimized particle of the classical PSO was converted into the particle beam of the MIPPO. The iteration process was weight controlled by calculating the Morris sensitivity between each input parameter and output index in the multi-quality objective prediction model, and finally the processing control window of each key parameter was determined according to the process parameter optimization results. The experimental results show that the MPPIO model can obtain the optimal parameter optimization results with the maximum processing capacity and meet the customized processing range requirements. The MPPIO model can reduce the difficulty of control and save production costs while ensuring the product properties is qualified.

Dual-phase oxide dispersion strengthened (ODS) steels of Fe−12Cr–xY (x = 0.1, 0.2, and 0.3 wt%) have been fabricated by casting, hot-forging and subsequent hot-rolling. Microstructure of the hot-rolled samples was carefully characterized by use of electron probe microanalysis (EPMA), electron backscatter diffraction (EBSD), and transmission electron microscope (TEM). The results show that all the samples consist of ferrite phase with coarse fiber grains (elongated along the rolling direction) and martensite phase in the form of fine block grains. As the Y addition increases, the ratio of ferrite to martensite and density of low-angle boundaries (LABs) within the martensite and ferrite grains do not change significantly. The Y2O3 particles introduced by self-oxidation during casting are survived without being dissolved or refined after hot-forging and hot-rolling. However, as the Y addition increases, the Y2O3 particles tend to aggregate with fine M23C6 and TaC carbides. The hardness of the sample with high Y additions is lower than that of the samples with none or low Y additions, which could be attributed to the aggregation coarsening of the yttria and TaC particles, resulting in a decrease in dispersion strengthening effect. The effect of Y additions on microtexture was also discussed.

The properties and performance of Zr-2.5 Nb alloys are strongly influenced by their crystallographic texture. As in similar Ti alloys, the texture evolution during hot-processing depends on the complex interactions between the α and β phases and involves deformation, annealing and phase transformation. Although the effect of temperature and deformation has been studied for extruded tube in this alloy, there is no data for texture development during rolling. There is some rolling data for Ti-64 (Ti–6Al–4V), but it is usually for just one of the phases and for a limited set of temperatures. We carried out hot-rolling trials from 700 °C–900 °C to reductions of 50%, 75% and 87.5% and found that the texture in both phases strengthens sharply before the β-transus and when both phases are present in similar amounts. At this point, the texture in α is a strong 0002 | | TD and the texture in β a strong { 001 } 〈 110 〉 rotated cube component. The results suggest there might be a synergistic effect between the two components, which includes dynamic phase transformation. The texture evolution towards stable α { 11 2 ¯ 0 } 〈 10 1 ¯ 0 〉 or { 11 2 ¯ 1 } 〈 10 1 ¯ 0 〉 crystallographic components and their final intensity depend on the starting texture. Texture was measured using electron-backscatter diffraction (EBSD) over large areas, with a β reconstruction software used to determine the high temperature β orientations. The texture development in Zr-2.5Nb appears similar to that reported for rolled Ti-64 at temperatures with equivalent phase fractions, although it is difficult to compare the two because of the lack of a titanium dataset as detailed as the one presented here. Image 1 • Detailed texture data set for hot-rolled Zr-2.5Nb, using EBSD of large areas. • 27 conditions characterised, covering 700 °C–900 °C and 3 levels of reduction. • Texture data for α and β (reconstructed) phases. • Unexpected texture strength peaks in both phases when volume fractions are similar. [ABSTRACT FROM AUTHOR]

• We study a new hot rolling scheduling problem from compact strip production. • We divide the problem into two sub-problems of minimizing virtual sheet strips and optimizing the sequence of sheet strips. • An improved heuristic is developed to minimize virtual sheet strips. • A multi-objective evolutionary algorithm is proposed to optimize the sequence of sheet strips. • The effectiveness of the presented algorithms is demonstrated by example instances from practice. This paper addresses a hot-rolling scheduling problem from compact strip production processes. At first, a mathematical model that consists of two coupled sub-problems is presented. The first sub-problem is the sheet-strip assignment problem that is about how to assign sheet-strips to rolling-turns with the objective of minimizing virtual sheet-strips. The second is the sheet-strip sequencing problem that is about how to sort the sheet-strips in each rolling-turn with the objective of minimizing the maximal changes in thickness between adjacent sheet-strips and the change times of the thickness so as to ensure high quality sheet-strips to be produced. And then, an improved hot-rolling scheduling heuristic is proposed to solve the sheet-strip assignment problem. A multi-objective evolutionary algorithm is developed to find the Pareto optimal or near-optimal solutions for the sheet-strip sequencing problem. Besides, the problem-specific knowledge is explored. The key operators including crossover operator, mutation operator and repair operator are designed for the multi-objective evolutionary algorithm. At last, extensive experiments based on real-world instances from a compact strip production process are carried out. The results demonstrate the effectiveness of the proposed algorithms for solving the hot-rolling scheduling problem under consideration. [ABSTRACT FROM AUTHOR]

Microstructural evolutions during hot deformation and annealing of alumina-forming austenitic (AFA) steel were investigated using electron backscatter diffraction (EBSD). Tensile properties of deformed and as-received AFA steels were also tested. The yield strength and ultimate tensile stress of deformed AFA steel increase gradually with the increase in rolling reduction, while the fracture elongation decreases rapidly. Specifically, after hot-rolling with the reduction of 40%, the yield strength of the annealed specimen is high to 773.2 MPa, and the fracture elongation of this sample is about 43.6%. The excellent mechanical properties can be attributed to the smaller average grain, larger Schmid factor and coincident site lattice (CSL) boundaries. Such a rapid decline of the elongation of AFA steel occurs due to increasing low angle grain boundaries (LAGB, <15°), the crystal defects and the degree of work hardening with the increase in rolling deformation. An approachable strategy to improve the tensile properties of annealed samples is to effectively hinder the dislocation motion during annealing at 700 °C when few LAGBs could transform into high angle grain boundaries (HAGB, >15°). [ABSTRACT FROM AUTHOR]

Hot plastic working behavior and microstructure evolution were investigated during a production process of four medium-Mn steels, which differed in Mn (3 and 5%) and Nb contents. The production process started with casting, followed by hot forging, rough hot-rolling and concluded with final thermomechanical processing, which was performed to obtain multiphase bainite-based alloys with some fractions of retained austenite. The rough rolling was composed of four passes with total true strain of 0.99 and finishing rolling temperature of 850 °C, whereas thermomechanical processing contained five passes and total true strain of 0.95 at a finishing rolling temperature of 750 °C. During the process, the force parameters were recorded, which showed that the rolling forces for steels containing 3% Mn are higher compared to the 5% Mn alloys. There was no significant influence of Nb on the rolling parameters. The produced as-cast microstructures were composed of dendritic bainitic-martensitic phases. A positive effect of Nb micro-addition on a refinement of the as-cast structure was noticed. The thermomechanical processed steels showed fine multiphase microstructures with some fractions of retained austenite, the fraction of which depended on the Mn content in steel. The steels containing 3% Mn generated higher forces both during rough and thermomechanical rolling, which is related to slower recrystallization softening in these alloys compared to the steels containing 5% Mn.

Entry temperature estimation is a major concern for finishing mill set-up in hot strip mills. Variations in the incoming bar conditions, frequent product changes and measurement uncertainties may cause erroneous estimation, and hence, an incorrect mill set-up causing a faulty bar head-end. In earlier works, several varieties of neuro-fuzzy systems have been tested due to their adaptation capabilities. In order to test the combination of the simplicity offered by Takagi–Sugeno–Kang systems (also known as Sugeno systems) and the modeling power of type-2 fuzzy, in this work, hybrid-learning type-2 Sugeno fuzzy systems are evaluated and compared with the results presented earlier. Systems with both empirically and fuzzy c-means-generated rules as well as purely fuzzy systems and grey-box models are tested. Experimental data were collected from a real-life mill; datasets for rule-generation, training, and validation were randomly drawn. Two of the grey-box models presented here reach 100% of bars with 20 °C or less prediction error, while two of the purely fuzzy systems improved performance with respect to purely fuzzy systems presented elsewhere, however it was only a slight improvement.