High-strength steel with excellent ductility is pivotal for the formability and safety of critical structural components.Here,a heterogeneous metastable lamellar steel,composed of alternating lamellar ferrite and aust...High-strength steel with excellent ductility is pivotal for the formability and safety of critical structural components.Here,a heterogeneous metastable lamellar steel,composed of alternating lamellar ferrite and austenite aligned with the rolling direction,was developed through an innovative combination of warm rolling and immediate annealing processes.This novel design overcomes the strength-ductility trade-off,achieving high ultimate tensile strength(∼1.2 GPa)and excellent uniform elongation(∼78%),pushing the product of ultimate tensile strength and uniform elongation to an ultra-high level(>90 GPa%).The high tensile strength is attributed to ultrafine lamellar grains and significant work hardening induced by the hetero-deformation and transformation-induced plasticity(TRIP)effect.The exceptional ductility is a result of the synergy of multiple plasticity mechanisms,including(i)the inherent plastic deformation ability of lamellar microstructure and the hetero-deformation-induced hardening in the early deformation period,(ii)the persistent TRIP effect induced by the lamellar austenite with high mechanical stability and the elimination of strain localization caused by prolonged strain hardening due to the coordinated deformation of lamellar austenite and ferrite in the middle deformation period,and(iii)delamination cracking in the late deformation period.This approach adopted in current work offers a straightforward and economically feasible pathway for fabricating advanced high-strength steel with superior performance.展开更多
The paper concerns an analysis of equilibrium problems for 2D elastic bodies with a thin Timoshenko inclusion crossing an external boundary at zero angle. The inclusion is assumed to be delaminated, thus forming a cra...The paper concerns an analysis of equilibrium problems for 2D elastic bodies with a thin Timoshenko inclusion crossing an external boundary at zero angle. The inclusion is assumed to be delaminated, thus forming a crack between the inclusion and the body. We consider elastic inclusions as well as rigid inclusions. To prevent a mutual penetration between the crack faces, inequality type boundary conditions are imposed at the crack faces. Theorems of existence and uniqueness are established. Passages to limits are investigated as a rigidity parameter of the elastic inclusion going to infinity.展开更多
基金support from the National Natural Science Foundation of China(Grant No.52304389)the China Postdoctoral Science Foundation(No.2022M720402)+2 种基金Huibin Wu and Gang Niu appreciate the support from the Fundamental Research Funds for the Central Universities(No.FRF-BD-23-01)Na Gong appreciates the support from the Structural Metal Alloy Program(SMAP,No.A18B1b0061)Gang Niu is grateful to Hatem S.Zurob for his insightful recommendation and expressive discussion.
文摘High-strength steel with excellent ductility is pivotal for the formability and safety of critical structural components.Here,a heterogeneous metastable lamellar steel,composed of alternating lamellar ferrite and austenite aligned with the rolling direction,was developed through an innovative combination of warm rolling and immediate annealing processes.This novel design overcomes the strength-ductility trade-off,achieving high ultimate tensile strength(∼1.2 GPa)and excellent uniform elongation(∼78%),pushing the product of ultimate tensile strength and uniform elongation to an ultra-high level(>90 GPa%).The high tensile strength is attributed to ultrafine lamellar grains and significant work hardening induced by the hetero-deformation and transformation-induced plasticity(TRIP)effect.The exceptional ductility is a result of the synergy of multiple plasticity mechanisms,including(i)the inherent plastic deformation ability of lamellar microstructure and the hetero-deformation-induced hardening in the early deformation period,(ii)the persistent TRIP effect induced by the lamellar austenite with high mechanical stability and the elimination of strain localization caused by prolonged strain hardening due to the coordinated deformation of lamellar austenite and ferrite in the middle deformation period,and(iii)delamination cracking in the late deformation period.This approach adopted in current work offers a straightforward and economically feasible pathway for fabricating advanced high-strength steel with superior performance.
文摘The paper concerns an analysis of equilibrium problems for 2D elastic bodies with a thin Timoshenko inclusion crossing an external boundary at zero angle. The inclusion is assumed to be delaminated, thus forming a crack between the inclusion and the body. We consider elastic inclusions as well as rigid inclusions. To prevent a mutual penetration between the crack faces, inequality type boundary conditions are imposed at the crack faces. Theorems of existence and uniqueness are established. Passages to limits are investigated as a rigidity parameter of the elastic inclusion going to infinity.
