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Stress distribution maps of the RVE at 20% of true plastic strain applied in the horizontal direction on all RVEs.
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Herein, micromechanical material deformation behavior of medium carbon steel—with varying cementite particle size and distribution—under monotonic tensile load is modeled. The statistical phase morphology data are collected from the microscopy images of 83% spheroidized C45EC steel. Virtual microstructures for nine different cases are constructed u...
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... stress distribution in all constructed RVEs at 20% true plastic strain is shown in Figure 4. In all cases, the stress carried by the cementite particles is much higher (%13 GPa) as compared with the stress in the ferrite matrix (%500 MPa). ...
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... stress distribution is generally observed as a significant contrast in the whole map, where some grains hold considerable stress. In contrast, some possess very low stress, as represented with the blue color in Figure 4. At 20% of the true plastic strain, the local strain maps of all RVEs are given in Figure 5. ...
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... strain in the matrix is observed in large cementite particle RVEs. Figure 4 and 5 show that the highest stresses are present in the cementite particles with the highest strain existing on the ferrite/cementite interface. ...
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... has been done to understand the contribution of the cementite particle size and distribution on the mechanical properties of spheroidized steels. The simulation results of local stress and strain distribution after 20% of the true strain are shown in Figure 4 and 5. It is observed that due to the changing morphology and distribution of cementite particles, the areas of high stress and strain change significantly. ...
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... stress distribution in all constructed RVEs at 20% true plastic strain is shown in Figure 4. In all cases, the stress carried by the cementite particles is much higher (%13 GPa) as compared with the stress in the ferrite matrix (%500 MPa). ...
Context 6
... stress distribution is generally observed as a significant contrast in the whole map, where some grains hold considerable stress. In contrast, some possess very low stress, as represented with the blue color in Figure 4. At 20% of the true plastic strain, the local strain maps of all RVEs are given in Figure 5. ...
Context 7
... strain in the matrix is observed in large cementite particle RVEs. Figure 4 and 5 show that the highest stresses are present in the cementite particles with the highest strain existing on the ferrite/cementite interface. ...
Context 8
... has been done to understand the contribution of the cementite particle size and distribution on the mechanical properties of spheroidized steels. The simulation results of local stress and strain distribution after 20% of the true strain are shown in Figure 4 and 5. It is observed that due to the changing morphology and distribution of cementite particles, the areas of high stress and strain change significantly. ...
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Citations
... The size of the cementite particle is controlled by the spheroidization rate at the austenitization temperature [40] and further substantially affects the SFC's strength and formability. Umar et al. [41] mentioned that the size of elliptical cementite particles was in the range of 0.4-2.5 µm, which accounted for a volume fraction of 0.17 in the SFC steel. In order to explore the role of the cementite size in the mechanical damage behavior of SFC steel, SFC model of three different particle sizes has been obtained under the same volume fraction of cementite particle (Fig. 6). ...
Inspired by the experimentally observed ferrite-cementite interface damage and ferrite matrix damage, this work develops a cross-scale method using the cohesive zone model (CZM) as a bridge to study the mechanical damage behavior of ferrite-cementite steel at the micro-nano scale. The CZM parameters for the damage region of ferrite-cementite steel were obtained by molecular dynamics (MD) simulations, which were then applied to cohesive elements in the finite element (FE) framework, thus enabling crack initiation and propagation at the micro-scale. Simulation results show that the ferrite-cementite interface is more susceptible to damage resulting in cracking compared to the ferrite matrix, which is consistent with the experimental observation that there are extensive debonded voids due to interface damage. The implementation of this work provides a new way to study the micro-nano scale mechanical behavior of heterogeneous materials containing both interface damage and matrix damage.
... The newly designed cylinder card clothing seems to obey this rule worldwide from different card clothing providers, including famous European factories [11][12][13]. [14], (a) the carding position for cotton fibers, (b) the carding position for synthetic fibers, (c) the concave face between a and b; (B) the newly invented card clothing with two teeth, h1 and h2-the tooth depth, R1 and R2-the bottom arc, α1 and α2-the working angle, l-the humb length. A typical dimension is also marked in the graph. ...
... Since this new card clothing was designed to be compatible with different fibers, the robustness of the carding clothing needed to be improved to deal with a much more complex and severe environment. Not only would the shape of the teeth need to be controlled [14], (a) the carding position for cotton fibers, (b) the carding position for synthetic fibers, (c) the concave face between a and b; (B) the newly invented card clothing with two teeth, h1 and h2-the tooth depth, R1 and R2-the bottom arc, α1 and α2-the working angle, l-the humb length. A typical dimension is also marked in the graph. ...
Changing the metallic card clothing on a carding machine is costly when the spinning mills want to card different fibers from cotton to terylene or vice versa. This article proposes a newly developed cylinder card clothing compatible with cotton and terylene fibers by Nb alloying of AISI 1090 steel so that the spinning mills can change the type of fiber without changing the card clothing. Based on an idea developed from classical carding balance theory to study the adaptability of the cylinder card clothing for cotton and terylene fibers, the wall shear stress was used as the basis for compatibility analysis of carding behavior and bearing capacity with cotton and terylene fibers and as the focus of this study. Nb alloying of AISI 1090 steel showed good wear resistance in carding areas after heat treatment with high hardness above 840 Hv0.2 and extremely fine grain grade of 13.5 class, which increased about 25% compared to conventional 80 WV. The testing results in the spinning mills, including one cotton and two terylene fibers, showed good performance with this newly developed card clothing. In conclusion, the card clothing made of Nb alloying of AISI 1090 steel can handle different fibers with acceptable carding performance.
... The concentrated distribution of carbide neighboring the grain boundary also has a negative effect on toughness because it promotes potential microvoid nucleation [15] and stress concentration, according to the simulation results of damask software [16]. The inhomogeneous strain distribution at interfaces is the origin of ductility reduction [17]. ...
In this study, the refinement of two microstructures was controlled in medium carbon 25Cr2Ni3MoV steel via multi-step tempering and partition (MTP) to achieve high cryogenic strength–ductility combinations. Microstructure evolution, the distribution of stress concentration, and microcrack formation and propagation during cryogenic Charpy impact testing were investigated. Compared with their performance in the quenching and tempering states (QT), the MTP steels showed a significant improvement in yield strength (1300 MPa), total elongation (25%), and impact toughness (>25 J) at liquid nitrogen temperature (LNT). The strengthening contributions mainly originated from the high dislocation density and refinement cementite (size: 70 nm) in the martensite lath (width: 1.5 μm) introduced by refined reversed austenite and its latter decomposition. The instrumented Charpy impact results indicated that cracks nucleated in the primary austenite grain (PAG) boundary for two steels due to the strain concentration band preferring to appear near PAGs, while cracks in the QT and MTP samples propagated along the PAGs and high-angle grain boundary (HAGB), respectively. The crystallized plasticity finite element simulation revealed that the PAG boundary with cementite precipitates of large size (>200 nm) was less able to dissipate crack propagation energy than the HAGBs by continuously forming a high strain concentration area, thus leading to the low-impact toughness of the QT steel.
... This large variation in the local strain around the MnS particle leads to a high contrast of local shear strain and is believed to be a critical factor in the formation of voids and growth phenomena. This is supported by previous research [29][30][31][32][33], in which scientists reported that the high shear strain pockets around the inclusion particles are responsible for the high local triaxiality and eventual initiation of local damage. In Figure 9, the local strain evolution along the five different measurement points (ferrite, ferrite-MnS interface, MnS, MnS-pearlite interface, pearlite) is presented with respect to the local strain evolution in the local area (shown by the dotted red rectangle). ...
... This large variation in the local strain around the MnS particle leads to a high contrast of local shear strain and is believed to be a critical factor in the formation of voids and growth phenomena. This is supported by previous research [29][30][31][32][33], in which scientists reported that the high shear strain pockets around the inclusion particles are responsible for the high local triaxiality and eventual initiation of local damage. Our results showed that the microstructural deformation behavior of the material is greatly influenced by the position and morphology of the MnS particles. ...
In this study, the behavior of MnS particles in a steel matrix is investigated through in situ tensile testing and digital image correlation (DIC) analysis. The goal of this research is to understand the mechanical behavior of MnS inclusions based on their position in the steel matrix. To accomplish this, micro-dog bone-shaped samples are prepared, tensile tested, and analyzed. Macro-mechanical results reveal that the material yields at a stress of 350 MPa and has an ultimate tensile strength of 640 MPa, with a total elongation of 17%. For micro-mechanical analysis, scanning electron microscopy (SEM) images are taken at incremental strains and processed using DIC software to visualize the local strain evolution. The DIC analysis quantifiably demonstrates that the local strain is highest in the ferrite matrix, and while lowest in the pearlite matrix, the MnS particles and the interfaces between different materials experienced intermediate strains. The research provides new insights into the micro-mechanical deformation behavior of MnS particles in a steel matrix and has the potential to inform the optimization of the microstructure and properties of materials containing MnS inclusions.
... High-performance AHSS and UHSS with good formability and weldability will occupy mainstream automotive steel from the perspectives of safety, energy conservation, and environmental protection [11]. AHSS for automobiles mainly includes cold-formed martensitic steel (MS), presshardening steel (PHS), complex-phase (CP) steel, quenching and partitioning (Q&P) steel, dual-phase (DP) steel, medium-manganese steel, and low-density steel, among which coldformed MS and PHS are martensitic steel and can reach grades with ultra-high-strength of above 1.5 GPa [9,[12][13][14][15][16][17]. Ultra-high-strength cold-formed MS and PHS have high strength, good formability, and excellent collision resistance and have good application prospects in automobile door guard beam, battery pack support frame, frame, A-pillar, seat guide rail, and bumper [9]. ...
With the background of emission peaks and carbon neutrality, light weight has become an irreversible trend in the development of the automobile industry. It is an inevitable choice to use a large amount of ultra-high-strength steels to realize light weight and safety of automobiles. Ultra-high-strength martensitic steels can be divided into hot-formed steels and cold-formed steels according to the forming process. In recent years, ultra-high-strength martensitic steels have been rapidly developed in automotive battery pack frameworks, door guard beams, bumpers, A-pillars, etc., depending on their good plasticity and advanced forming technology. In this paper, the recent progress of ultra-high-strength martensitic steels for automobiles is systematically reviewed, the mechanisms of alloying, strengthening, and toughening are emphatically expounded, and the hydrogen embrittlement problems in application are summarized. Finally, the prospects of manufacture and application of ultra-high-strength martensitic steels for automobiles in the future are forecasted.
... The single-phase steels due to their low strength and ductility are less favorable for engineering applications [11,12]. Therefore, multiphase materials such as spheroidized steels [13][14][15], DP steels [16][17][18], metal matrix composite (MMC) with fiber/particle-reinforcement [19][20][21] are used in most engineering applications due to their high energy absorbing capacity, higher oxidation, and corrosion resistance [22][23][24]. Newly developed metastable austenitic stainless matrix MMCs reinforced with 5-10 % partially stabilized zirconia (Mg-PSZ) particles were shown to depict significantly higher energy absorption capacity [25,26]. ...
In this work, two simulation models were used to investigate the local deformation and damage behavior of partially stabilized zirconia-reinforced metastable austenitic steel composites and validated by experimental results. An in situ quasi-static tensile test on a miniature dog bone sample is performed under an electron microscope up to 6.4% true strain. A commercial digital image correlation program, VEDDAC, is used to process micrographs obtained at incremental strains to calculate the evolution of the local experimental strain distribution. The initial experimental micrograph was transformed into a geometry file for simulation model. In two different simulation models, the ceramic/matrix interface is assumed once to be perfect, and secondly, the interface is modeled using cohesive elements. The results showed that the stress concentration sites of the cohesive model continuously change along the interface because of the effect of debonding, while it maintains its position in the non-cohesive model. At 6.4 % global strain, the relative error of the strain between the DIC and the cohesive model is only 6 %. The numerical model with cohesive interface accurately predicts local stress and strain, as well as the position and evolution of damage accidents, and can therefore be reliably used by other researchers.
Highlights:
• The mechanical deformation and damage behavior of the austenitic matrix reinforced with zirconia particles is carried out.
• The local Von Mises strain distribution and interfacial damage evolution is performed using the digital image correlation.
• The relative error of the strain between the experimental and numerical simulation with the cohesive element model is observed to be only 6 %.
• The quantitative progression of damage evolution in micrographs helps to validate the predictions of the cohesive element model.
... One of them is the smaller and more widely distributed cementite particles. They may pin the recrystallised grains and thus prevent their coarsening [28]. Another is the 111 < 112 > deformed grains with higher stored energy, in which the number of nuclei formed should be larger, and the proportion of recrystallised grains should initially increase more rapidly. ...
After continuous annealing process (CAP) at 790°C, 85% of the coils of 50% cold-rolled low carbon microalloyed (LCM) steel did not exhibit yield-strength (YS) on the target range, while the 70% cold-reduced LCM coils did. In this context, the non-isothermal recrystallisation kinetics of ferrite for the above two full-hard LCM steel were investigated using differential scanning calorimetry and the Friedman differential isoconversional method. The recrystallisation kinetics of ferrite for the two deformed states showed different behaviour. Regarding a fixed degree of cold-rolling deformation, the soaking temperature was found as the manageable parameter to control YS during CAP. Consequently, a suitable YS of the 50% cold-rolled LCM steel was achieved by setting the soaking temperature at 773°C.
... Since the previous works have shown that the second phase inclusions are major players in defining the formability of the material [15,41,55], a special focus was given to them in this work. Previous work [51][52][53][54][55][56] shows that the morphology and distribution of the second phase inclusions dictate the formability limit and damage degradation in a material. ...
This work investigates a ferrite matrix with multiple non-metallic inclusions to evaluate their influence on the global and local deformation and damage behavior of modified 16MnCrS5 steel. For this purpose, appropriate specimens are prepared and polished. The EBSD technique is used to record local phase and orientation data, then analyze and identify the size and type of inclusions present in the material. The EBSD data are then used to run full phase crystal plasticity simulations using DAMASK-calibrated material model parameters. The qualitative and quantitative analysis of these full phase simulations provides a detailed insight into how the distribution of non-metallic inclusions within the ferrite matrix affects the local stress, strain, and damage behavior. In situ tensile tests are carried out on specially prepared miniature dog-bone-shaped notched specimens in ZEISS Gemini 450 scanning electron microscope with a Kammrath and Weiss tensile test stage. By adopting an optimized scheme, tensile tests are carried out, and local images around one large and several small MnS inclusions are taken at incremental strain values. These images are then processed using VEDDAC, a digital image correlation-based microstrain measurement tool. The damage initiation around several inclusions is recorded during the in situ tensile tests, and damage initiation, propagation, and strain localization are analyzed. The experimental results validate the simulation outcomes, providing deeper insight into the experimentally observed trends.
... Many efforts have been made to reach a framework connecting these boundary problems with physical phenomena [18]. Many numerical methods, i.e., Finite Element Method (FEM), Finite Volume Method (FVM), spectral method, and the Fast Fourier Transform (FFT)-based (Crystal Plasticity Finite Element Method) CPFEM method are usually used [22,23]. The difference between FE and SP methods lies in their homogenization technique and consequent time saving, as Shanthraj et al. [24] reported. ...
This study analyses the effect of martensite grain size and its volume fraction in dual-phase (DP) steel on (1) the formability limit, (2) average global behavior under different loading conditions, and (3) damage initiation. The virtual RVEs (Representative Volume Elements) were constructed using DREAM.3D software with a variation of microstructural attributes. The numerical simulations were carried out using DAMASK, which evaluates the polycrystalline material point behavior and solves versatile constitutive equations using a spectral solver. The simulations were post-processed to obtain global and local stress, strain, and damage evolution in constructed RVEs. The global results were processed to obtain FLDs according to Keeler-Brazier (K-B) and Marciniak and Kuczynski (M-K) criteria. In this work, the capability of microstructure-based numerical simulations to analyze the FLDs has been established successfully. From Forming Limit Diagrams (FLDs), it was observed that formability changes by changing the strain hardening coefficients (n-values), the martensite fraction, and martensite grain sizes of DP steels. The improved formability was observed with lower martensite fraction, i.e., 17%, decreased martensite grain size, i.e., 2.6 µm, and higher strain hardening coefficient. The M-K approach shows the better capability to predict the formability by various loading conditions and clarifies the necking marginal zone of FLD. The damage propagation is also strongly affected by the loading conditions. The current study would be a good guide for designers during the manufacturing and selecting of appropriate DP steels based on the service loading conditions.
... particle shape, size, morphology, and orientation in an improved way. [13][14][15] Therefore, actual EBSD data have been adopted to model the materials in the current study. ...
... [7] As the commercial spheroidization process consumes a significant amount of time and energy, therefore, suitable degree of spheroidization for specific material must be established to get the desired mechanical properties by utilizing the optimal resources. [13] This is a fairly challenging and technologically expensive process for which the microscopic attributes of steel need to be studied and optimized. The recent advances in crystal plasticity modeling and simulations have made it possible to virtually analyze the effect of microscopic attributes on the mechanical response of the crystalline material. ...
... The current study is designed to advance the initial investigations from virtual RVEs of spheroidized medium carbon steels on micromechanical behavior reported by Umar et al. [13] to study the same attributes based on EBSD data of three spheroidization states of the same steel. The effect of spheroidization degree and heat treatment process on the microstructural evolution and ultimately on the deformation behavior of the material is analyzed under the application of uniaxial tensile load using numerical simulations. ...
Herein, micromechanical simulations for three different states of spheroidized steel (C45EC) are conducted under quasi‐static tensile loading based on the actual texture and crystallographic orientation from electron backscatter diffraction (EBSD) data. Data denoising is conducted with MTex (open‐source Toolbox with MATLAB) for cleaning up the EBSD data. Crystal plasticity‐based full phase numerical simulations are performed on these constructed representative volume elements (RVEs) to analyze the local stress and strain evolution in C45EC steels. The local results of the simulations exhibit important insights into deformation evolution influenced by the size and clustering of cementite particles as well as crystallographic orientations of ferrite grains. It is observed that the full phase simulation model helps predict the local microstructural details for overall mechanically improved properties of the steels. Spheroidized steel samples (97%) show the most favorable mechanical response as adequate strain hardening with extended elongation is desired for cold‐working of parts. The current work is another step forward to fine‐tune the microstructural attributes of medium carbon steels for an improved mechanical response. The effect of thermomechanical treatment of spheroidized steel is studied by combining electron backscatter diffraction (EBSD) characterization of the microstructure with 2D fast Fourier transform (FFT)‐based crystal plasticity simulations. Uniaxial tension is considered and results are discussed with varying size and distribution of cementite particles. Detailed analysis provides useful insights into factors influencing the global and local deformation.
