International Journal of Plasticity最新文献

{"title":"Coupled cellular automata-crystal plasticity modeling of microstructure-sensitive damage and fracture behaviors in deformation of α-titanium sheets affected by grain size","authors":"","doi":"10.1016/j.ijplas.2024.104138","DOIUrl":"10.1016/j.ijplas.2024.104138","url":null,"abstract":"<div><div>Concerning the micro-scale deformation of titanium metal sheets, the number of grains in the sheet thickness direction decreases, and their formability exhibits a strong grain size sensitivity. Meanwhile, the twinning-induced dynamic recrystallization (TDRX) associated with grain size significantly affects the fracture behavior in the microforming of titanium sheets. Therefore, an accurate prediction of formability to improve manufacturing reliability remains challenging in the microforming of miniaturized titanium components. To address this issue, an in-depth understanding of the grain size-dependent TDRX behavior and its role in damage and fracture development in the microforming of α-titanium sheets is critical, and a coupled cellular automata-crystal plasticity (CA-CP) modeling framework was thus developed as an approach providing efficient solutions and insightful comprehensions of the issue. For the proposed modeling framework, a kinematic model for TDRX was established and integrated into the CP model by the CA algorithm. As a result, the microstructure evolution caused by TDRX was regarded as an intrinsic part of the constitutive behavior to connect heterogeneous plastic deformation and damage evolution through data transmission between the CP model and the CA algorithm. Additionally, the coupled CA-CP modeling framework was validated with the internal defect morphologies and deformation microstructures characterized by X-ray computed tomography (X-CT) and electron backscattered diffraction (EBSD). Experiment and simulation results demonstrated that the fine recrystallized (DRXed) grains were generated after the twin fragmentation when the dislocation density at twin boundaries reached a threshold of 9.2 × 10¹³ /m². After TDRX, the dislocation density and the stress concentration intensity in recrystallization regions were revealed to decrease, accounting for the ductility improvement. Nevertheless, the dislocation density at twin boundaries was determined to decrease with the increase of grain size, leading to less twin fragmentation and the absence of TDRX. The uncoordinated deformation between fine DRXed grains motivated defects to grow spherically into microvoids, thereby preventing premature intergranular cracks along twins/grain boundaries. Ultimately, the deformation microstructures resulting from TDRX with the decrease of grain size were confirmed to control the brittle to ductile fracture transition of α-titanium sheets. The presented modeling framework and simulation procedure were validated to be able to predict the material integrity affected by crystalline microstructure in the deformation of titanium metal sheets.</div></div>","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":null,"pages":null},"PeriodicalIF":9.4,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142330065","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A variational framework for Cahn–Hilliard-type diffusion coupled with Allen–Cahn-type multi-phase transformations in elastic and dissipative solids","authors":"","doi":"10.1016/j.ijplas.2024.104131","DOIUrl":"10.1016/j.ijplas.2024.104131","url":null,"abstract":"<div><div>This article presents a variational framework for coupled chemo-mechanical solids undergoing irreversible micro-structural changes at infinitesimal strains. The coupled problem is characterised by phenomena such as phase transitions, micro-structure coarsening and swelling. It is an extension of our previous work on variational inelasticity for a conserved chemo-mechanical setting to a unified conserved and non-conserved setting which include multi-phase transformations. The variational framework, again governed by continuous-time, discrete-time and discrete-space–time incremental variational principles, is outlined for coupled diffusion-phase transformation phenomena in elastic and dissipative solids. For the sake of simplicity, focus is restricted to isothermal conditions. It is shown that the governing macro- and micro-balance equations of the coupled problem appear as Euler equations of these minimisation and saddle point principles. In contrast to our previous work, extended variational principles (with the gradient of the chemical potential and phase fractions) are constructed that account for diffusion-phase transformation coupling. This is achieved by Legendre transformations. Note that the local–global solution strategy is still preserved and the resulting system of symmetric non-linear algebraic equations are solved by Newton–Raphson-type iterative methods. The applicability of the proposed framework is demonstrated by numerical simulations that qualitatively characterise lower bainitic micro-structure.</div></div>","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":null,"pages":null},"PeriodicalIF":9.4,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0749641924002584/pdfft?md5=da440451b0eb401c9c154a235203195d&pid=1-s2.0-S0749641924002584-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142314602","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tailoring multi-type nanoprecipitates in high-entropy alloys towards superior tensile properties at cryogenic temperatures","authors":"","doi":"10.1016/j.ijplas.2024.104132","DOIUrl":"10.1016/j.ijplas.2024.104132","url":null,"abstract":"<div><div>In this work, the quasi-static tensile properties in the face-centered cubic-based Al_0.5Cr_0.9FeNi_2.5V_0.2 HEAs containing two types of heterogeneous nanoprecipitates, i.e., dual-lamellar and spherical nanoprecipitates, at ambient (293 K) and liquid nitrogen (77 K) temperatures are thoroughly investigated. The microstructure formed by aging at 873 K comprises L1<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> and body-centered cubic dual-lamellar (DL) nanoprecipitates. In contrast, aging at 773 K results in solely spherical L1<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> nanoparticles. Both nanoprecipitates enhance mechanical strength as temperatures drop to 77 K; however, the DL nanoprecipitates additionally boost the work hardening rate, whereas the spherical nanoparticles notably improve ductility. To investigate the underlying deformation mechanisms, we perform interrupted mechanical tests and microstructure characterizations at various strains. The DL nanoprecipitates are observed to go through a multistage work hardening rate response by gradually introducing new boundaries to block dislocation motion, activating the stacking fault (SF) networks, and forming Lomer–Cottrell locks. A combination of interface hardening, dislocation hardening, SF-induced hardening, and precipitation hardening in DL samples leads to stronger hetero-deformation-induced hardening at cryogenic temperatures. In comparison, while samples with only spherical nanoparticles exhibit a monotonous decrease in the work-hardening rate, the spherical nanoparticles can be sheared by dislocations, effectively alleviating strain concentration and thereby enhancing ductility at cryogenic temperatures. Overall, this work provides practical design principles of nanoprecipitates for fine-tuning the balance of strength and ductility in FCC-based HEAs at cryogenic temperatures.</div></div>","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":null,"pages":null},"PeriodicalIF":9.4,"publicationDate":"2024-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142326475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tailoring thickness debit for high-temperature fatigue resistance of Inconel 718 superalloy fabricated by laser powder bed fusion","authors":"","doi":"10.1016/j.ijplas.2024.104137","DOIUrl":"10.1016/j.ijplas.2024.104137","url":null,"abstract":"<div><div>The thickness debit often leads to uncertainty regarding the fatigue performance of laser powder bed fusion (LPBF)-fabricated Inconel 718 thin-walled components and restricts the structural design of these components. Aiming to address this issue, fatigue properties of LPBF-fabricated Inconel 718 homogenized at various temperatures were investigated at 650 °C using specimens with different thicknesses. The results reveal a pronounced influence of both the thickness debit and the intricate interplay between the microstructural and geometrical scales of the thin-walled specimens on their fatigue life at 650 °C. The fatigue life of the thin-walled specimens with the same microstructural scale reduces with decreasing the ratio (<em>t/d</em>) of the specimen thickness (<em>t</em>) to the grain length (<em>d</em>). The coupling effect is described by a mechanism model correlated with the geometrical and microstructural scales of the specimens, in which continuous damage mechanics (CDM) and calculation of the yield strength have been considered. Based on the model, a criterion of <em>t/d</em> &gt; 6.2 for the LPBF-fabricated Inconel 718 specimens homogenized at 1100 °C, and <em>t/d</em> &gt; 8.8 for those homogenized at 1065 °C are proven to be satisfied to ensure a longer and more stable fatigue life of the thin-walled specimens serving at 650 °C. Elevating the homogenization temperature from 1065 °C to 1100 °C results in an extension of the fatigue life for specimens of the same thickness. This enhancement is attributed to the improved ability of grains to coordinate local deformation, as well as the reduced prevalence of elongated Laves and other phases, which typically serve as preferential sites for crack initiation and propagation. The finding suggests that the thickness debit in high-temperature fatigue resistance of LPBF-fabricated components can be minimized by tailoring the heat treatment strategy.</div></div>","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":null,"pages":null},"PeriodicalIF":9.4,"publicationDate":"2024-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142330104","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rapid assessment of the creep rupture life of metals: A model enabling experimental design","authors":"","doi":"10.1016/j.ijplas.2024.104133","DOIUrl":"10.1016/j.ijplas.2024.104133","url":null,"abstract":"<div><div>Prediction of the creep rupture life of engineering metals is critical for qualification and design of new materials. The use of long-term creep tests and the need to quantify the performance variability in <em>a priori</em> similar systems hinder the rapid creep assessment of a given material. Therefore, it is essential to develop methods that can extrapolate the long-term performance of alloys and the associated variability from short-term experiments. To this end, this study introduces a new model which enables the estimation of the rupture life of a material for a given stress and temperature. This model relies on two components. First, a new relation for the minimum creep rate (MCR) of materials is introduced. It includes a stress dependent stress exponent allowing the model to capture the variation of MCR across a wide range of temperatures and stresses. Second, employing the Monkman-Grant (MG) law, we establish a relation between stress, temperature and creep rupture life. Together, these two elements yield a new closed-form mathematical expression for the Larson Miller parameter as a function of stress and temperature. This expression captures the creep rupture time for many metals (Gr91, Copper, Gr122 and 347H) and compares favorably with alternate empirical approaches. The model is then used to assess the minimum duration of creep rates necessary to qualify the material up to 100000h. It is found that depending on the material system, creep tests as few as five limited to 5000 h for steels (Gr91, Gr122, 347H) and 100 h for copper are sufficient to model creep lifetimes. Finally, using a Bayesian inference-based approach to calibrate the model, we demonstrate that variability in rupture life can be captured via the quantification of the uncertainty in the model parameters and extrapolated from a limited number of short to moderately short creep tests; thereby paving the way for accelerated creep testing.</div></div>","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":null,"pages":null},"PeriodicalIF":9.4,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142326476","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The dependence of Zener-Hollomon parameter on softening behavior and dynamic recrystallization mechanism of a biodegradable Zn-Cu-Mg alloy","authors":"","doi":"10.1016/j.ijplas.2024.104120","DOIUrl":"10.1016/j.ijplas.2024.104120","url":null,"abstract":"<div><div>The Zn-Cu-Mg alloy exhibits good strength, ductility, anti-aging and antibacterial properties, which lays the foundation for developing high performance Zn-based biodegradable alloys. However, the constitutive equation and dynamic recrystallization (DRX) behavior of this alloy remain unclear, making the optimization of hot processing parameters almost dependent on trial and error. This work aims to address these issues by investigating the hot compression process. The calculated average activation energy Q of this alloy is 141.338 KJ⋅mol^-1, exhibiting excellent heat resistance. The deformed microstructure strongly depends on the Zener-Hollomon parameter (Z=<span><math><mover><mrow><mi>ε</mi></mrow><mo>˙</mo></mover></math></span>exp(<span><math><mfrac><mi>Q</mi><mrow><mi>R</mi><mi>T</mi></mrow></mfrac></math></span>)). Discontinuous DRX (DDRX) dominates at low lnZ, which has a significantly different orientation from the parent grain. Continuous DRX (CDRX) occurs within the grain and at grain boundaries, and is dominant at middle lnZ, mainly through activation 〈a〉 or/and 〈c+a〉 slip systems. Additionally, the activation of prismatic slip further promote CDRX, and most CDRX grains inherit the 30°[0001] orientation from the parent grains. The volume fraction of DRX demonstrates a decreasing trend followed by an increasing trend with increasing lnZ. At high lnZ, the increase of DRX grains is conducive to weakening the texture, and twin-induced DRX (TDRX) is significantly promoted, leading to an increase in both peak stress and strain hardening rate. Furthermore, the grains with c-axis aligned parallel to the compression direction (CD) are more prone to twinning, while the c-axis perpendicular to CD are the hard orientation of basal slip and compression twins. TEM results reveal that a decrease of c/a value promotes the activation of non-basal slip near the twin boundary, and the highly active 〈c〉 and 〈c+a〉 slips contribute to the increase of strain hardening rate. The results of this study are significant for understanding the workability of Zn-Cu-Mg alloys at high lnZ due to its high efficiency and low cost.</div></div>","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":null,"pages":null},"PeriodicalIF":9.4,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142306438","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhancing fatigue crack propagation resistance of heterostructured Al composites and multistage crack mechanisms","authors":"","doi":"10.1016/j.ijplas.2024.104136","DOIUrl":"10.1016/j.ijplas.2024.104136","url":null,"abstract":"<div><div>High tensile strength and low fatigue crack propagation (FCP) rate are hard to achieve simultaneously in aluminium (Al) based materials, which has been a long-lasting topic. It is because the traditional strengthening mechanisms may lead to the increase in FCP rate. In this work, we developed dual-level heterostructures by incorporating the <em>in-situ</em> synthesized TiB₂ particles into Al matrix, to create particle-lean zones (PLZs) and particle-rich zones (PRZs) by extrusion. Fine grains were introduced by particle-associated local recrystallization in PRZs. By means of particle and grain size distribution, a heterostructured Al composite featuring with the coarse grains in PLZs and fine grains in PRZs was fabricated. It was found that simultaneous enhancement of both the strength and FCP resistance of Al composite was achieved through the development of heterostructures. During FCP, the PRZs can retard the growth of slip bands and increase crack deflection frequency while the PLZs increase the crack deflection distance and plastic deformation capability at crack tip. The fracture behavior of composite during FCP depended on grain characteristics, particles and stress intensity range. The detailed cracking behavior for typical &lt;100&gt;_Al and &lt;111&gt;_Al grains in different FCP stages was identified. The associated models were developed for different FCP behaviors. Particularly, the quantitative relationship between Pairs parameters and microstructure features was established, which was critical to understand fatigue properties of Al composite reinforced by small particles. These findings can provide a strategy to design metal materials with an excellent combination of both static and dynamic mechanical properties.</div></div>","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":null,"pages":null},"PeriodicalIF":9.4,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142314097","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Achieving superior strength-ductility balance by tailoring dislocation density and shearable GP zone of extruded Al-Cu-Li alloy","authors":"","doi":"10.1016/j.ijplas.2024.104135","DOIUrl":"10.1016/j.ijplas.2024.104135","url":null,"abstract":"<div><div>Pre-stretching is commonly employed to accelerate ageing precipitation kinetics in wrought Al-Cu-Li alloys, but uneven precipitation resulting from dislocation pile-ups often degrades ductility. Herein, the strength and ductility of extruded Al-Cu-Li alloy are significantly improved through a novel thermomechanical treatment, involving pre-ageing and pre-stretching, followed by low-temperature interrupted ageing. A superior balance between high yield strength (∼ 657 MPa) and good ductility (elongation to fracture of ∼ 13.5 %) is obtained, with elongation increased by 105 % compared to the conventional T8 temper, while maintaining a respectable yield strength. Microstructure analysis reveals that dense Guinier–Preston (GP) zones induced by pre-ageing effectively dissipate energy from dislocation sliding, resulting in a uniform dislocation configuration even at 8 % pre-stretching. However, the GP zone density is greatly reduced due to their dissolution following pre-stretching. Upon interrupted ageing, the reprecipitation of GP zones forms a homogeneous mixture of δ′, GP zones, and T₁ phases. This combination alleviates local stress concentrations and lengthens the dislocation mean free path during tensile testing by shearing the GP zones at multiple sites, thereby improving ductility. Simultaneously, T₁ precipitates strengthen the alloy by pinning dislocations and promoting dislocation cross-slip, improving work hardening capacity. The dissolution of GP zones also redistributes the Cu atoms within the matrix, further enhancing the intrinsic ductility of the Al matrix. These findings offer valuable insights for developing high-performance wrought Al-Cu-Li alloys.</div></div>","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":null,"pages":null},"PeriodicalIF":9.4,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142306436","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Crack-tip cleavage/dislocation emission competition behaviors/mechanisms in magnesium: ALEFM prediction and atomic simulation","authors":"","doi":"10.1016/j.ijplas.2024.104134","DOIUrl":"10.1016/j.ijplas.2024.104134","url":null,"abstract":"<div><div>Structural properties and reliability of materials can be improved by increasing fracture toughness. At the atomic scale, the fracture is a material separation process, and the fracture toughness of materials is associated with the atomic-scale crack-tip behaviors/mechanisms. The crack-tip behaviors are relevant to the energy state of atoms in the system. Atomic thermal oscillation increases with increasing temperature, which may affect/alter the crack tip behaviors. This work is the first to investigate the temperature-dependent crack-tip cleavage/dislocation emitting competition in magnesium (Mg) using anisotropic linear elastic fracture mechanics theory, Density Functional Theory (DFT), and atomic simulation. Crack-tip behaviors are examined using a specially designed ‘K-field’ loads model. DFT calculations show that a single crystal system with lower entropy and higher Gibbs free energy implies stronger interatomic bonding that favors a higher <em>K_Ic</em>. Changes in the stress distribution initiate a brittle-ductile transition in crack-tip behavior. The ductile crack tip can be blunted by continuous crack-tip dislocations nucleation/slip, and the evolution of the ductile crack-tip geometry from sharp to semicircular structure significantly decreases the stress concentration at the crack tip. A new criterion of the crack-tip force vector is established, which reasonably explains the geometrical evolution of ductile crack tip where the angle <span><math><mi>θ</mi></math></span> between the crack plane and the slip plane is <span><math><mrow><msup><mn>0</mn><mo>∘</mo></msup><mo>&lt;</mo><mi>θ</mi><mo>&lt;</mo><msup><mn>90</mn><mo>∘</mo></msup></mrow></math></span> and <span><math><mrow><mi>θ</mi><mrow></mrow><mo>=</mo><msup><mn>90</mn><mo>∘</mo></msup></mrow></math></span>. This work expands the atomic-scale brittle/ductile crack-tip behaviors/mechanisms of Mg, which provides a reference for crack-tip behavior analysis in engineering research.</div></div>","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":null,"pages":null},"PeriodicalIF":9.4,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142306450","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dislocation accumulation-induced strength-ductility synergy in TRIP-aided duplex stainless steel","authors":"","doi":"10.1016/j.ijplas.2024.104130","DOIUrl":"10.1016/j.ijplas.2024.104130","url":null,"abstract":"<div><p>In this study, we investigate the intrinsic mechanism of intensive and progressive transformation-induced plasticity (TRIP) effects and their different strength-ductility synergies using a resource-efficient 15Cr-2Ni duplex stainless steel. The progressive TRIP material exhibits a ductility that is more than twice that of the intensive TRIP material, as well as, a larger product of the ultimate tensile strength and ductility. This is attributed to the dislocation accumulation caused by different grain sizes of strain-induced martensite depending on the stability of the <em>γ</em> phase, which determines the strength and work hardening of steel. When the stability is low, the <em>γ</em> phase is sensitive to loaded stress and transformed into dispersed fine martensite immediately after yielding at a high rate. It induces a sigmoid-shaped dislocation accumulation to an approximately 10-fold increase in the dislocation density at a limited strain, resulting in intensive work hardening and a large ultimate tensile strength. As the stability is adequate, the <em>γ</em> phase is transformed into coarse martensite laths with a high critical load stress, which is initiated from a delayed strain at an extremely low rate and steadily accelerated as the strain increases. This process induces a gradually increased dislocation accumulation to a 2–3-fold increase in the dislocation density at large strains, resulting in progressive work hardening and an excellent ductility.</p></div>","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":null,"pages":null},"PeriodicalIF":9.4,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142235219","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}