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Improving the room-temperature Bendability of Mg-3Al-1Zn alloy sheet by introducing a bimodal microstructure and the texture re-orientation

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International Journal of Minerals,Metallurgy and Materials 2022年第7期29卷 1322-1333页

作者： Chao He Yibing Zhang Ming Yuan Bin Jiang Qinghang Wang Yanfu Chai Guangsheng Huang Dingfei Zhang Fusheng Pan State Key Laboratory of Mechanical Transmissions College of Materials Science and EngineeringChongqing UniversityChongqing 400044China School of Chemistry and Materials Science Hubei Engineering UniversityXiaogan 432000China National Engineering Research Center for Magnesium Alloys Chongqing UniversityChongqing 400044China School of Mechanical Engineering Yangzhou UniversityYangzhou 225127China School of Mechanical and Electrical Engineering Shaoxing UniversityShaoxing 312000China

A significant enhancement of Bendability was achieved by the introduction of bimodal microstructure for AZ31B alloy sheets via pre-compression and subsequent annealing(PCA)process.This combined treatment led to the c-axis of the extracted samples that were inclined by 30°to the rolling direction(30°sample)further shifting toward the rolling direction(RD)and resulting in a higher Schmid factor(SF)value of basal slip under the RD tensile stress.Furthermore,the bimodal microstructure that was introduced by the PCA process broke the damage bands(DBs)in the initial hot rolled AZ31B alloy sheets and gave rise to a more uniform strain distribution in the outer tension region of the bending samples,in which the tensile deformation was accommodated by the equally distributed{101^(-)2}tension twinning and basal slip.Consequently,the bimodal microstructure,shifted basal texture and the modification of DBs were responsible for the significant enhancement in the Bendability of the AZ31 alloys.

关键词： magnesium alloy pre-compression texture bimodal microstructure Bendability

Development of a hot-rolled 980 MPa advanced high-strength steel with excellent flangeability and Bendability

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Baosteel Technical Research 2022年第4期16卷 16-20页

作者： ZHANG Chen WANG Huanrong Research Institute Baoshan Iron&Steel Co.Ltd.Shanghai 201999China

A new 980 MPa advanced high-strength steel(AHSS) with excellent Bendability and flangeability has been studied and industrially produced, typical of tensile strength, fractured elongation, and hole expansion ratio(HER) exceeding 980 MPa, 10%,and 30%,respectively.The 90° V-type bending perpendicular to the rolling direction can satisfy the R/t=1.0 requirement, indicating excellent Bendability.Systematic evaluations of industrial trial-produced 980 MPa hot-rolled AHSS have been conducted, including microstructure, tensile properties in three directions, HER,Bendability, fatigue limit strength, and forming limit.The microstructure of the newly developed 980 MPa AHSS primarily consists of fine bainite and a small amount of martensite-austenite constituent.The practical yield and tensile strength are higher than 800 and 980 MPa, respectively, with typical elongation of 13% and HER of around 40%.The good combination of the newly developed 980 MPa AHSS is primarily attributed to the fine bainitic microstructure, resulting in excellent flangeability and Bendability.In addition, the newly developed 980 MPa AHSS has good fatigue and forming properties, making it suitable for the production of chassis and suspension components.

关键词： hot rolled advanced high-strength steel(AHSS) flangeability Bendability hole expansion ratio(HER)

A Study on Multi-defect Constrained Bendability of Thin-walled Tube NC Bending Under Different Clearance

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Chinese Journal of Aeronautics 2011年第1期24卷 102-112页

作者： LI Heng YANG He State Key Laboratory of Solidification Processing School of Materials Science and Engineering~ Northwestern Polytechnical University Xi'an 710072 China

Thin-walled tube numerical control （NC） bending is a tri-nonlinear physical process with multi-defect and multi-die constraints. The clearance on each contact interface is the major factor to indicate the contact conditions. A three-dimensional-finite element （3D-FE） model is established to consider the realistic dynamic boundary conditions of multiple dies under ABAQUS/Explicit platform. Combined with experiment, numerical study on bending behavior and Bendability under different clearance between tube and various dies is conducted in terms of wrinkling, wall thinning and cross section deformation. The results show that （1）with smaller clearance of tube-wiper die and tube-mandrel, the wrinkling can be restrained while the wall thinning It and cross-section deformation Id increase; while excessive small clearance blocks tube materials to flow past tangent point and causes piles up, the onset of wrinkling enhances It and Id. （2）Both It and Id decrease with smaller clearance of tube-pressure die; the wrinkling possibility rises with larger clearance on this interface if the mandrel’s freedom along Y-axis is opened; smaller clearance of tube-bend die prevents wrinkling while increases It, and the clearance on this interface has little effect on Id. （3）A modified Yoshida buckling test （YBT） is used to address the wrinkling mechanisms under normal constraints in tube bending： the smaller clearance may restrain wrinkling efficiently; the smaller wall thickness, the less critical clearance needed; the critical clearance for tube bending 38 mm×1 mm×57 mm （tube outer diameter×wall thickness×centerline bending radius） equals about 20% of initial wall thickness.

关键词： Bendability clearance defects thin-walled tube numerical control bending

Study on the Bendability and toughness of a 1 500 MPa cold-rolled martensitic sheet steel

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Baosteel Technical Research 2016年第3期10卷 28-34页

作者： ZHU Xiaodong XUE Peng LI Wei ZHANG Hanlong Research Institute Baoshan Iron&Steel Co.Ltd.Shanghai 201900China State Key Laboratory of Development and Application Technology of Automotive Steels(Baosteel) Shanghai 201900China

Cold rolled martensitic sheet steels are achieving more and more applications in car-making because of their ultra-high strength and potential for weight reduction. The relatively low plasticity of ultra-high strength martensitic steels might be a drawback for the applications in the aspects of forming and safety protection function and should be significantly noted. A 1 500 MPa grade cold rolled martensitic sheet steel has been studied to investigate the Bendability at 90 degree bending and impact toughness as well as fracture surface morphology at various temperatures. Some discussions have been made basing upon the experiment data to get some understanding on the performance of the materials under various conditions and on how to make use of this kind of ultra high strength steel properly.

关键词： cold rolled martensitic steel sheet Bendability toughness

Comparison of microstructures and mechanical properties of composite extruded AZ31 sheets

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Journal of Magnesium and Alloys 2019年第4期7卷 547-554页

作者： Yanfu Chai Yan Song Bin Jiang Jie Fu Zhongtao Jiang Qingshan Yang Haoran Sheng Guangsheng Huang Dingfei Zhang Fusheng Pan State Key Laboratory of Mechanical Transmissions College of Materials Science and EngineeringChongqing UniversityChongqing 400044China Chongqing Academy of Science and Technology Chongqing 401123China Research Institute for New Materials Technology Chongqing University of Arts and SciencesChongqing 402160China Shanghai Aerospace Equipment Manufactory Shanghai 200245China

The microstructures and mechanical properties of the composite extruded AZ31/AZ31 and AZ31/4047 Al sheets were investigated and made a comparison to the conventional extruded AZ31 sheet.Owing to the introduced intense shear deformation at the interface during the composite extrusion,grain refinement and tilted texture were detected in AZ31 layers of the AZ31/AZ31 and AZ31/4047 Al sheets,while the conventional extruded AZ31 sheet exhibited a relative coarse,inhomogeneous microstructure and strong basal texture.The compressiontension yield ratio was increased gradually from the AZ31 to the AZ31/AZ31 and AZ31/4047 Al sheets.Besides,the AZ31/4047 Al sheet could successfully accomplish the whole bending forming process at room temperature,while the AZ31 and AZ31/AZ31 sheets were both bend-formed to failure with significant cracks in the outer tensile region under the identical bending parameters.Moreover,under the same bending strain,both the outward offset degree of strain neutral layer and the sheet thickening were more serious in the AZ31/4047 Al composite sheet than those of the AZ31 and AZ31/AZ31 sheets.The foremost reason was the quite wide gap of material properties between Mg alloy AZ31 layer(tensile loading in the outer region)and Al 4047 layer(compressive loading in the inner region).

关键词： Mg alloy sheet Composite extrusion Tension-compression yield asymmetry Bendability

Recent progress of efficient flexible solar cells based on nanostructures

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Journal of Semiconductors 2021年第10期42卷 93-102页

作者： Yiyi Zhu Qianpeng Zhang Lei Shu Daquan Zhang Zhiyong Fan Department of Electronic&Computer Engineering The Hong Kong University of Science and TechnologyHong Kong 999077China HKUST-Shenzhen Research Institute Shenzhen 518057China Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology HKUSTHong Kong 999077China

Flexible solar cells are important photovoltaics(PV)technologies due to the reduced processing temperature,less material consumption and mechanical flexibility,thus they have promising applications for portable devices and building-integrated applications.However,the efficient harvesting of photons is the core hindrance towards efficient,flexible PV.Light management by nanostructures and nanomaterials has opened new pathways for sufficient solar energy harvesting.Nanostructures on top surfaces provide an efficient pathway for the propagation of light.Aside from suppressing incident light reflection,micro-structured back-reflectors reduce transmission via multiple reflections.Nanostructures themselves can be the absorber layer.Photovoltaics based on high-crystallinity nanostructured light absorbers demonstrate enhanced power conversion efficiency(PCE)and excellent mechanical flexibility.To acquire a deep understanding of the impacts of nanostructures,herein,a concise overview of the recent development in the design and application of nanostructures and nanomaterials for photovoltaics is summarized.

关键词： solar cells nanotechnology antireflection Bendability PCE

Effects of quenching and over-aging temperatures on mechanical properties of ultra-high strength cold-rolled martensite steels

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Baosteel Technical Research 2019年第1期13卷 1-8页

作者： ZHANG Hanlong ZHU Xiaodong XUE Peng Research Institute Baoshan Iron & Steel Co.Ltd. State Key Laboratory of Development and Application Technology of Automotive Steels( Baosteel)

As cold-formed steel has the highest strength-to-weight ratio of any material,ultra-high strength martensitic steel is attracting great interest from global car manufacturers. This paper explores the effects of the quenching and over-aging temperatures on the strength and cold Bendability of C-Mn-Si martensitic steel. Due to its high carbon content,water-quenched C-Mn-Si martensitic steel has high hardenability and can obtain ultra-high tensile strength and uniform martensitic morphology when the water-quenching temperature is higher than 710 ℃.Increasing the over-aging temperature of this experimental steel decreases its tensile strength,increases the total elongation,and first increases then decreases the yield point until reaching a peak at 180 ℃. Besides,when increasing the over-aging temperature,the Bendability of this experimental steel initially improves and then decreases,and reaches its optimal Bendability at an over-aging temperature of 180 ℃. Based on SEM characterization and a microhardness distribution analysis,the over-aging temperatures were found to affect the size of the carbides and differences in the microhardness of the experimental steel. Therefore,they have significant influence on Bendability.

关键词： martensitic steel annealing Bendability

The relevance of Niobium microalloying in dual phase steels with optimized mechanical properties

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Baosteel Technical Research 2010年第S1期4卷 47-页

作者： Hardy MOHRBACHER NiobelCon bvba 2970 Schilde Belgium

Dual phase steel is nowadays widely applied in automotive construction as hot rolled and cold rolled HDG grades.The strength and elongation of DP steels are principally determined by the ratio of ferrite and marteniste in the microstructure.However,for practical forming in the press shop additional properties are important such as Bendability and hole expansion ratio.These characteristics relate to the morphology and distribution of the phases in the microstructure.Niobium microalloying can influence not only the strength of DP steels but also particularly the phase morphology and homogeneity leading to significant improvement of the mechanical properties.The paper will show processing strategies involving Nb microalloying in DP steel production.The metallurgical mechanisms induced by Nb are discussed.This is also related to damage mechanisms occurring in DP steel during forming or application.Particularly the issue of delayed fracturing in ultra high strength DP steel will be addressed.

关键词： grain refinement intercritical annealing phase distribution delayed cracking hole expansion Bendability