金属塑性成形的应变路径效应:机制、表征与应用
Strain Path Effects in Metal Plastic Forming: Mechanisms, Characterization, and Application
通讯作者: 詹 梅,zhanmei@nwpu.edu.cn,主要从事高性能轻量化构件精确塑性成形理论与技术研究
责任编辑: 李海兰
收稿日期: 2025-09-29 修回日期: 2025-11-26
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Corresponding authors: ZHAN Mei, professor, Tel:
Received: 2025-09-29 Revised: 2025-11-26
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作者简介 About authors
樊晓光,男,1985年生,教授,博士
应变路径是决定塑性成形金属构件形状、组织和性能等成形质量的重要因素。为提升成形质量,通常需要设计非线性的复杂应变路径。复杂应变路径必然引起更复杂的多尺度变形行为,因此,其机制分析和表征成为塑性成形领域研究的前沿和热点。本文系统探讨了复杂应变路径下的宏观力学响应、损伤行为以及显微组织和织构演化规律,总结了路径历史在多尺度变形机制中的作用特征。梳理了基于应变路径效应的材料成形有限元建模思路和方法,包括材料本构模型、极限预测与损伤模型和微观组织演化模型,阐述了其在提升变形预测精度和工艺模拟效果方面的价值。分析了工程应用中面向成形性和服役性能优化的路径设计策略,突出了其在形性调控方面的潜力。最后,对金属塑性成形的应变路径效应未来的研究方向进行了展望。
关键词:
Strain path is a critical factor governing the forming quality of metallic components, including their geometry, microstructure, and service performance. Achieve high-quality forming often requires the use of nonlinear and complex strain paths, which inevitably give rise to multiscale deformation behaviors. Understanding and characterizing these mechanisms has therefore become a frontier topic in the field of plastic forming. This review synthesizes recent advances in the investigation of macroscopic mechanical responses, damage behavior, and microstructural and textural evolutions under complex strain paths, emphasizing the central role of stress path history in shaping multiscale deformation mechanisms. Finite element modeling strategies that account for strain path effects are discussed, including constitutive models, limit prediction and damage models, as well as microstructure evolution models, with particular attention to their roles in improving predictive accuracy and process simulation capabilities. Engineering-oriented approaches to strain path design are also summarized, highlighting their potential for optimizing formability and service performance. Finally, perspectives on future research directions are presented.
Keywords:
本文引用格式
樊晓光, 肖云腾, 詹梅, 马飞, 高鹏飞, 郑泽邦, 张昕, 邵光大, 伍寓铭.
FAN Xiaoguang, XIAO Yunteng, ZHAN Mei, MA Fei, GAO Pengfei, ZHENG Zebang, ZHANG Xin, SHAO Guangda, WU Yuming.
塑性成形是汽车、航空航天和高端装备制造等领域的关键基础技术[1,2],也是材料、几何和接触非线性耦合的复杂物理过程。材料非线性的重要表现之一是应变路径敏感性,即材料的塑性应变张量在应变空间随时间演化的连续变化过程。已有研究[3]基于塑性应变张量和应变速率张量建立了对应变路径变化的定量描述框架。在实际成形过程中,材料往往经历多道次变形和复杂模具约束,形成连续或不连续的应变路径变化。此类变化会诱发背应力的积累与重排、非线性卸载、回弹以及Bauschinger效应等复杂力学响应,导致材料在屈服、硬化行为和各向异性等方面表现出显著的路径依赖性[4,5]。同时,应变路径通过改变应力状态轨迹,影响损伤萌生与扩展机制,进而决定成形极限和断裂模式[6]。在微观组织演化层面上,应变路径效应广泛影响位错组态分布、再结晶过程、孪生行为以及相变机制,对织构演化也有着重要调控作用[7,8]。此外,不同合金体系、变形方式和路径序列也会导致微观组织演化呈现显著差异,进而影响最终性能表现[9,10]。因此,系统揭示复杂应变路径下宏微观变形机制的耦合规律,是实现工艺优化和形性调控的重要基础。
随着结构轻量化、复杂化以及高可靠性需求的持续增长,新材料体系不断涌现,复杂构件和高端服役场景对成形工艺提出了前所未有的挑战[11]。在此背景下,传统的依赖简单路径和载荷控制的工艺模式,在满足多样化几何精度、力学性能与服役安全等方面已难以胜任,尤其面对高性能铝合金、高熵合金、先进镁合金、钛合金等新兴材料,以及轻量化、集成化等复杂结构的实际需求,更加多样化的应变路径设计成为提升材料利用率、优化组织和性能、实现性能按需调控的有效工具。系统深入地研究复杂应变路径对于调控材料微观组织、实现结构功能一体化以及突破现有工艺极限具有关键支撑作用。近年来,围绕复杂应变路径效应开展的多尺度、跨学科研究,为实现材料-结构-性能一体化优化提供了理论基础和技术储备,对高端装备制造领域的持续创新和高质量发展具有深远的战略意义[12,13]。
经过多年探索,应变路径效应研究已形成清晰的发展脉络。早期工作[14]通过反向加载实验和成形极限描述揭示了路径改变引发的再屈服和瞬态硬化等现象。随后,Liao等[15]在屈服准则与硬化规律中引入路径依赖性,有效提升了回弹预测和非比例加载模拟精度。随着先进表征技术的发展,微观尺度的现象学观测和分析不断深入,建立了微观组织演化与宏观力学响应间的关联规律[16]。在建模方面,跨尺度有限元方法和数据驱动模型不断完善和迭代,提升了模拟的精度和工程适用性[3,17,18]。在此基础上,研究重点由机理探索扩展到工艺设计,路径优化在板料成形、锻造成形、轧制成形、挤压成形等诸多塑性成形领域中均展现出提升成形性和服役性能方面的显著潜力[7,19,20]。
鉴于应变路径效应在理论研究和工程实践中的重要价值,本文对其研究进展进行了系统综述。重点阐述了路径效应对宏观力学响应、损伤行为及微观组织演变的影响机制,梳理了耦合路径敏感性的多尺度建模思路与方法,概述了面向形性优化的路径设计策略与应用前景,并对未来的发展方向进行了展望,此领域的持续深化将为高端装备制造迈向高精度、高性能目标提供不可替代的理论支撑与技术驱动力。
1 复杂应变路径下的宏微观变形行为
塑性成形过程中的宏微观变形行为可直接反映应变路径效应。路径改变在宏观尺度引发屈服强度和硬化行为的突变,影响变形均匀性;在微观尺度则深刻作用于损伤行为以及微观组织演化。本节将围绕宏观力学响应、损伤行为、显微组织和织构演化四个方面,系统解析路径效应的跨尺度作用机制。
1.1 宏观力学响应
复杂应变路径对金属材料的宏观力学行为具有显著影响。这种路径依赖性体现在屈服强度、加工硬化率和均匀塑性能力等方面,典型力学响应包括Bauschinger效应、瞬态硬化以及永久软化。其中,Bauschinger效应表现为反向加载(如拉伸-压缩、剪切-反剪切等)下材料屈服强度降低和硬化率突变。现有研究表明,这些现象主要归因于背应力作用、微观组织演化以及材料本征变形机制等方面。
图1
除背应力作用外,复杂路径下的微观组织演化亦是影响宏观力学响应的关键因素[24],目前的研究重点多聚焦于金属结构类型及合金体系的影响。Shi等[25]认为,不同晶体结构合金在非比例加载路径下的屈服行为存在差异,其中hcp结构镁合金的各向异性屈服行为主要受控于位错滑移和取向演化,这一观点在钛合金相关研究中亦被证实[26]。此外,孪生变形起到的影响同样被广泛关注。Hama等[27]发现,商业纯Ti在不同应变路径下均表现出明显的Bauschinger效应,并强调了孪生与去孪生对加工硬化行为具有显著影响。Wroński等[28]进一步揭示了孪生、去孪生和二次孪生等微观机制的交替激活行为,使得材料在不同路径下呈现出截然不同的硬化特征(图2[28])。
图2
图3
图3
QP980钢在不同预应变条件下的应力-应变曲线[29]
Fig.3
Stress-strain curves of quenching and partitioning steel (QP980) specimens at various pre-strain levels deformed along RD[29] (UT-UC—uniaxial tension (UT) followed by compression,UC-UT—uniaxial compression (UC) followed by tension, RD—rolling direction, T—tension, C—compression)
(a) UT-UC (b) UC-UT
1.2 损伤演化行为
在认同路径效应促进损伤演化的研究中,加载历史被证明对断裂应变与损伤累积具有决定性作用。Fincato和Tsutsumi[33]通过数值模拟明确了比例和非比例载荷下材料的损伤演化差异,认为当主应力与应变方向不同时,损伤演化会加速。Itoh和Yang[34]则进一步将材料失效寿命缩短归因于非比例载荷下的附加硬化行为,同时也强调了材料晶体结构的影响。Yu等[35]在2219-W铝合金断裂行为研究中发现,合金的断裂响应由Portevin-Le Chatelier (PLC)带扩展、共轭剪切带形成以及最大剪切面连续旋转三大关键机制相互作用控制,这种耦合作用加速了剪切驱动的孔洞生长,并促进了不同应变路径下损伤模式的应力状态敏感性变化。图4[35]反映了2219-W铝合金在不同应变路径下的断裂机理。
图4
图4
2219-W铝合金在不同应变路径下的断裂机理[35]
Fig.4
Fracture mechanisms of 2219-W aluminum alloy under different strain paths[35] (MSP—maximum shear plane, ND—normal direction, KAM—kernel average misorientation, IPF—inverse pole figure) (a-c) plane strain tension (PST) specimen (Fig.4b is the RD × ND middle section of PST after fracture; Fig.4c shows the KAM maps and IPF-Z maps of two squared positions in Fig.4b) (d-f) shear (SH) specimen (d), stress components on the shear plane of the fracture element for SH specimen (e), and comparisons of the rigid body and MSP rotation angles of the same element as Fig.4e (f) (σxx, σyy, and σxy are stress com-ponents) (g, h) UC specimen (g) and SEM images of cross cracks on the RD × ND outer surface (h)
另一方面,部分研究则强调复杂路径具有延缓损伤的作用。以双相钢为例,Wollenweber等[36]在研究中发现,相较于单一拉伸,拉伸-弯曲等非比例路径可在局部产生负应力三轴度,抑制甚至闭合孔洞,从而降低整体损伤程度。Marcadet和Mohr[37]则通过大应变压缩-拉伸断裂实验证实预压缩能够明显提升反向拉伸时的断裂应变,增强延展性。相应地,Yu和Yoon[38]基于应变空间损伤指数,从另一角度揭示了预拉伸对压缩断裂行为的影响。他们发现经历大应变预拉伸的铝合金压缩试样在断裂处剪切带更为显著(图5[38]),反映出损伤模式从孔洞主导向剪切局部化的转变。由此可见,复杂路径下损伤演化往往伴随断裂机理的切换与混合。
图5
1.3 显微组织演化行为
在复杂应变路径作用下,显微组织演化行为通常表现为多种机制的耦合特征,主要包括位错重组、再结晶、孪晶演化以及应变诱导相变等过程。尽管不同材料体系对路径的响应存在差异,但总体上均体现出“应力状态轨迹-显微演化机制-宏观性能”之间的内在耦合关系,合理的路径设计已被证实是显微组织调控的有效手段。
图6
再结晶行为是材料实现晶粒细化的主要方式,应变路径通过影响位错密度、亚结构和相界面演变,显著影响再结晶动力学和球化过程。Poths等[41]在钛合金等温扭转实验中发现,路径反转会抑制亚晶界形成,从而降低片层球化驱动力。相比之下,多向加载更易实现组织均匀化和晶粒细化。Zhang等[26]通过多向等温锻造促进片层钛合金发生充分动态再结晶。Zhao等[42]在TA15钛合金研究中发现,当两次压缩方向垂直时片层动态再结晶最为显著。此外,多轴压缩实验[43]还表明,α相几何取向的调整可促进球化进程,较大正向应变可使得球化程度进一步提高(图7[43])。由此可见,合理的路径设计不仅调控再结晶动力学,也通过几何约束促进片层组织均匀球化。
图7
图8
图9
图9
304LN不锈钢在不同应变路径下的相分布[8]
Fig.9
Phase distribution of 304LN stainless steel under different strain paths[8] (Insets shows the strain vs time waveforms for different strain paths. OPT—out of phase triangular, OPS—out of phase sinusoidal, OPZ—out of phase trapezoidal, ε—applied axial strain, γ—applied shear strain)
1.4 织构演化行为
织构演化是金属塑性变形过程中晶粒取向逐渐趋向特定分布集中的过程,对力学性能、塑性各向异性和成形极限具有深远影响。在复杂应变路径下,织构演化行为不仅依赖于变形方式和条件,还与材料的晶体结构类型和主导变形机制密切相关。为此,本节从hcp、fcc和bcc三类典型晶体结构出发,梳理不同合金体系的织构演化规律。
图10
铝合金作为典型的fcc结构金属,其织构演化主要通过多滑移系协调变形实现,路径改变可有效诱发织构类型和强度的变化。El-Danaf[53]的研究表明,具有等通道转角挤压(ECAP)织构的1050AA合金在经历平面应变压缩时向典型轧制织构转变的趋势明显,说明路径变换可实现铝合金织构类型的有效调控。Dhara等[54]在AA6111-T4铝合金中对比了单轴与双轴路径,发现双轴应变促进低强度{111}织构形成,且卸载-重新加载过程会进一步影响织构强度,揭示了加载历史对织构稳定性的持续影响。Zeng等[55]还发现,2219铝合金在平面应变压缩中,因应变路径效应表现出明显塑性各向异性,并认为其机制与织构演化密切相关。
图11
2 应变路径效应的多尺度建模
应变路径效应显著影响材料在复杂载荷下的力学响应及微观演化,对其精准建模是塑性成形理论和工艺优化的基础。当前的多尺度建模研究通常涵盖宏观、细观和微观三个层次。其中,细观和微观尺度建模能够通过位错演化、孪生激活、晶体取向变化及再结晶动力学等多种机制解析,为宏观模型的构建提供必要的物理机理支撑和参数化数据来源[59~63]。而在应变路径效应的研究和应用中,宏观尺度建模依然处于核心地位。这不仅因为宏观本构框架能够直接捕捉屈服、硬化、回弹和断裂等工程上关切的力学行为,还因其便于与有限元模拟及实际工艺优化相结合,从而在工艺预测和设计中具有不可替代的重要性。因此,有关细观和微观建模的研究进展本文暂不详述,本节将聚焦于考虑应变路径效应的宏观尺度均匀化模型的研究现状,从材料本构模型、极限预测与损伤模型和微观组织演化模型三方面展开综述。
2.1 材料本构模型
在当前研究发展阶段,宏观模型的构建和应用仍面临着实验数据获取难度大和工艺验证成本高的现实挑战。为突破这一瓶颈,研究者开展了基于物理机制的晶体塑性有限元模拟方法研究,并不断挖掘其显著优势[73]。Zecevic等[74]基于几何必需位错提出新型晶体塑性模型,实现了对双相钢循环加载下硬化速率、非线性卸载及Bauschinger效应的准确预测。在此基础上,Kim等[75]提出VPSC-RGBV晶体塑性模型,将位错密度动态演化纳入其中,在保持与HAH模型近似精度的同时减少参数数量。Xu等[76]系统研究了晶粒尺寸与路径效应的耦合影响,并进一步考虑预变形效应以提升模型精度。其他研究如Iftikhar等[77]提出的Taylor型晶体塑性有限元框架以及周驰等[78]改进的Voce/Hollomon模型,也从数值方法和硬化规律修正角度推动了路径效应建模在铝合金、相变诱导塑性(TRIP)钢中的工程应用。
除晶体塑性有限元模拟方法外,机器学习等数据驱动技术的引入也极大地促进了材料本构建模的发展[79]。当前,本领域的机器学习应用主要集中在两种模式,分别为通过机器学习算法识别特定本构模型公式的参数[80]和创建完全取代本构模型的元模型[81]。在参数识别方面,机器学习元模型可以直接用于逆向识别,即通过输入力、位移和应变等力学实验数据获得元模型参数,随后将待表征材料的实验结果导入元模型中以预测材料本构参数;也可以与经典优化算法结合,采用参数输入、力学响应输出的形式,通过优化迭代寻找最佳参数使得实验结果与模型预测相吻合。相较于传统方法,机器学习模型在处理非线性关系和大数据样本时展现出更高的精度与效率。为进一步突破本构模型固有的局限,研究者也积极探索以机器学习元模型直接取代显式本构关系的可行性[82]。Jang等[83]利用人工神经网络(ANN)创建了基于数据训练的元模型,取代了von Mises屈服和各向同性硬化准则,所建模型在多种应变路径下表现出良好泛化能力,并可有效嵌入有限元模拟框架。Gorji等[81]则采用回归神经网络(RNN)对AA5182和DC05钢在应变路径变化时的塑性变形进行建模,实现了对任意加载路径下材料变形响应的高精度预测,其准确性可与当前广泛应用的材料本构模型相当。
2.2 极限预测与损伤模型
2.3 微观组织演化模型
理解材料在复杂加载下的微观响应,需要将应变路径历史显式引入到模拟框架中。相比于单一加载,复杂路径往往伴随应力状态剧烈波动与滑移系竞争开动,使位错积累、孪晶形核和晶粒旋转过程相互交织。如何在建模中体现这种历史效应,从而可靠预测显微组织和织构演化,已成为当前研究的关键挑战之一。
在显微组织建模方面,学者们普遍通过位错密度演化、孪晶机制及动态再结晶过程的引入来表达路径依赖特征。Qiao等[92]基于EVPSC-TDT (elastic-viscoplastic self-consistent model with the consideration of twinning and detwinning)模型,考虑{10
与显微组织模型相比,基于织构演化的建模方法更侧重晶粒旋转和滑移激活对力学响应的影响。Kitayama等[95]提出的晶体学位错硬化模型能够捕捉路径变化对织构演化的影响,并揭示晶粒旋转与应力-应变响应的耦合关系。Zhang等[96]基于Kurdjumov-Sachs关系构建层状代表性体积单元,模拟了低碳钢在不同路径下的组织和织构演化,表明原始奥氏体取向和路径变化共同决定硬化行为和织构特征。此外,Ibragimova等[97]还提出了一种融合机器学习和晶体塑性的模型框架,利用晶体塑性模拟所得数据对ANN模型进行训练,实现了对材料应力响应和织构演化的高效预测。该方法充分发挥了数值模拟与数据驱动模型的协同优势。总体来看,这些研究既体现了传统晶体塑性方法的成熟,也展示了智能算法在高效计算方面的潜力,但在跨尺度精度与计算效率之间的平衡仍待探索。
3 工程应用中面向形性优化的应变路径设计
随着应变路径效应在机理和建模层面的认识加深,其工程化价值逐步凸显。近年研究由基础规律转向工艺反演和路径优化:在不同成形方法中,通过合理规划应变历史,可提升成形稳定性并优化服役性能。
3.1 板料成形
在板料成形性优化领域,早期研究多以经典成形极限图(FLD)为判据[98],但随后的工作显示其对应变路径的敏感性远超早期预期,复杂应变路径下的极限演化已成为研究的热点。Dhara等[99]通过系统实验验证了不连续路径转换对铝合金板变形潜力的改善作用。然而,Leotoing和Guines[100]在AA5086合金中观察到当预应变接近20%时,后续双轴拉伸反而诱发过早失效,成形性急剧下降(图12[100])。这一矛盾说明,板料成形性的提升并非随预应变增加而线性改善,而取决于预应变水平、加载比例与显微组织的协同作用。另外,Schlosser等[101]在锌板成形研究中强调晶体取向和第二相分布可能削弱路径优化效果,认为板料成形的宏观路径设计需与组织、织构调控相结合。
图12
3.2 锻造成形
在锻造成形过程中,应变路径的合理规划对于提升成形稳定性和综合性能具有关键作用。目前,通过调整锻造路径历史实现材料形性提升的研究重点普遍集中于晶粒细化、织构演化等方面。Salandari-Rabori等[108]针对多向锻造镁合金的显微组织和力学性能表现展开研究,发现多道次换向锻造后,组织内部动态再结晶程度明显增加,最终获得晶粒细小、取向分散的均匀等轴组织,对综合力学性能提升有明显帮助。值得注意的是,初始道次下材料表现为强塑性协同提升,随着后续多道次变形的进行,塑性改善愈加显著。王俐[109]和樊晓光等[110]在TB6合金药型罩的成形研究中采用拔长-多向锻造复合路径,系统比较了加载历史对构件均匀性的影响。结果表明,反向加载路径下构件成形效果最佳,其主要原因在于路径历史对片层α相几何取向和晶体取向的调整(图13[109])。
图13
3.3 轧制成形
在轧制过程中,应变路径改变可在成形性、强塑性与各向异性之间实现再平衡。Chen等[111]提出的正反轧制和坯料预成形方法可有效减少带横肋圆柱构件填充不均匀的缺陷,显著提升成形质量。钛合金相关研究进一步证明了路径调控的潜力。Gao等[112]发现,相较于单向轧制,多级交叉轧制不仅保持了更高的屈服强度和延伸率,还显著降低了各向异性;Li等[113]同样采用交叉轧制实现了Ti60合金织构由横向向基面类型转变,从而有效改善了拉伸性能均匀性。Rouzbeh等[114]在Al/Mg复合板中利用交叉轧制路径诱导晶粒细化,从而实现成形性与强度同步提升,不同应变路径制备的Al/Mg复合板材拉伸性能对比如图14[114]所示。
图14
3.4 挤压成形
对于挤压成形工艺,应变路径的合理设计被广泛证明能够显著改善材料的成形稳定性与力学性能。张治民等[115]系统总结了多种挤压成形新技术,并首次提出将直线运动与旋转运动相匹配,主动增加强剪切变形的多向加载旋转挤压成形技术,实现材料的均匀强韧化和薄壁内环高筋构件的整体精确成形。Wang等[40]在CGP工艺研究中表明,交叉路径带来的晶粒细化和织构优化效果远优于传统路径,为复杂构件的局部强化提供了切实可行的方案。具体到ECAP技术(图15[116]),Gautam等[7]在对镁合金实验中发现路径A和路径BC能够有效细化晶粒并提升硬度和延展性,而路径C由于剪切方向抵消,导致性能退化。与之形成对比的是,Mills等[116]在锌合金ECAP研究中强调,路径BC和路径C的成形效果更好,分别在强度提升和成形性改善方面更具优势。这说明最优路径的选择需结合材料本征机制,不可一概而论。
图15
图15
标准等通道转角挤压(ECAP)路线下的变形应变路径[116]
Fig.15
Deformation strain paths under standard equal channel angular pressing (ECAP) routes[116]
(a) illustration of a cubic element undergoing defor-mation due to shearing after a single pass of ECAP
(b) evolution of deformation in each plane for all 4 ECAP routes after up to 8 passes of ECAP
4 总结与展望
应变路径效应作为金属塑性成形领域的核心问题,贯穿于宏观力学响应、损伤行为、微观组织演化等多个层面。已有研究借助多样化的实验方法,系统揭示了应变路径对再屈服特性、瞬态硬化、回弹行为及断裂机制的影响规律,并逐步阐释了背应力演化、滑移系激活竞争、孪生变形行为以及再结晶和相变动力学等内在机理。在建模方面,基于路径依赖的本构模型、跨尺度有限元方法和晶体塑性模拟不断成熟,显著提升了复杂加载条件下材料行为的预测精度和效率。同时,融合物理机制与数据驱动的新一代混合建模方法,展现出良好的工程适用性和可移植性。在应用层面,应变路径优化已在板料成形、锻造成形、轧制成形、挤压成形等多种工艺中表现出提升成形性和服役性能的潜力。综上,应变路径效应相关研究已从初期现象学观测逐步走向机理解析和模型构建,并延伸至工程应用,为发展高性能塑性成形技术奠定了坚实基础。
基于以上研究进展,应变路径效应研究仍存在诸多关键问题有待深入探索。未来研究可重点关注以下几个方向。
(1) 明确新型与复杂材料体系下应变路径效应的普适性与差异性。现有研究多集中于铝、钢、钛等传统合金,对高熵合金、镁稀土合金、钛铝化合物,以及增材制造合金和金属基复合材料等体系关注不足,可迁移性结论有限。未来可从多材料体系出发,开展系统对比与统一评价,采用标准化非比例加载和路径转变方案,构建跨材料体系的路径依赖数据库。
(2) 深化特种能场辅助成形与应变路径的耦合效应认识。目前关于电、磁、超声、激光及局部热场等能场协同调控的研究多停留在工艺现象层面,对其与应变路径的耦合作用机制认识尚不全面。未来有必要建设多能场辅助的复杂路径试验平台与数值模拟体系,引入原位监测与闭环调控方法,实现多能场条件下复杂路径变形机理的系统研究和验证。
(3) 构建多维度、多尺度原位表征体系。当前表征方法仍普遍依赖变形后制样或准静态实验,难以在复杂路径切换和高应变速率下实时捕捉显微组织及织构的瞬态演化。未来可整合同步辐射、中子衍射、原位电镜及数字图像相关技术,配合高速加载和可编程路径控制,形成可追溯的数据采集和标定体系,为机理模型提供可靠数据支撑。
(4) 提升多尺度材料本构与损伤模型普适性。现有框架虽已能显式追踪路径历史对力学响应与损伤演化的耦合影响,并实现成形极限的路径敏感预测,但在材料迁移性和路径突变稳健性等方面仍显不足。未来可继续发展融合物理机理与数据驱动的混合建模方法,结合跨尺度实验验证,建立参数可迁移、物理意义明确的模型体系,提升复杂加载路径下的模型预测能力和工程适用性。
(5) 推动人工智能与成形优化方法的深度融合。现有数据驱动模型高度依赖高质量数据集,获取成本高、周期长,且优化可靠性低。未来应加强人工智能与多尺度模型的系统融合,构建可解释、低数据依赖的混合建模框架,结合数字孪生与机器学习,实现成形工艺的稳健优化和反向设计。
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Plane stress yield function for aluminum alloy sheets-part II: FE formulation and its implementation
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On the non-linear unloading behavior of a biaxially loaded dual-phase steel sheet
[J].
Investigation of evolving yield surfaces of dual-phase steels
[J].
Constitutive equations for cyclic plasticity and cyclic viscoplasticity
[J].
Investigation of advanced strain-path dependent material models for sheet metal forming simulations
[J].
Extension of homogeneous anisotropic hardening model to cross-loading with latent effects
[J].
Prediction of the yield surface evolution and some apparent non-normality effects after abrupt strain-path change using classical plasticity
[J].
A new simplified distortional hardening model for nonlinear strain paths
[J].
Progress of crystal plasticity theory and simulations
[J].
晶体塑性理论及模拟研究进展
[J].回顾了大变形晶体塑性理论的发展历程、本构模型和均匀化方法,综述了晶体塑性理论成果和典型应用场合。从流动模型、加工硬化模型和状态变量演化的角度对比分析了唯象的和基于物理机理的晶体塑性模型的理论基础和优缺点;阐述了平均场晶体塑性模型和全场晶体塑性模型的特点和适用场合;从金属多晶体材料的各向异性、织构演化、非均匀塑性变形、可成形性、尺度效应、损伤断裂行为、热变形和微观组织演化、虚拟测试等角度介绍了晶体塑性模拟的典型应用场合,并展望了该领域的未来发展趋势。
Dual-phase steel sheets under cyclic tension-compression to large strains: Experiments and crystal plasticity modeling
[J].
A crystal plasticity model for describing the anisotropic hardening behavior of steel sheets during strain-path changes
[J].
Crystal plasticity-based analysis and modelling of grain size and strain path dependent micro-scaled deformation mechanisms of ultra-thin sheet metals
[J].
Evolution of subsequent yield surfaces with plastic deformation along proportional and non-proportional loading paths on annealed AA6061 alloy: Experiments and crystal plasticity finite element modeling
[J].
A mixed hardening model for TRIP steel considering strain path change
[J].To improve the precision of FEM simulation of transformation induced plasticity (TRIP) steel, a Voce-Hollomon mixed hardening model (V/H model) was proposed based on the results of two steps tensile test of sheet. The results of two steps tensile test show that the cross-harndening effect is observed when the angle between two tensile directions increase, and the hardening rate and fracture elongation decrease with the increese of angle. According to the experimental observation, two weight coefficients for the Voce term and the Hollomon term were introduced into V/H model by taking the strain path angle as independent variable. The weight of Hollomon term and Voce term were defined to decrease and increase respectively with the increase of angle, which indicated the effect of strain path change on hardening behavior. A two steps finite element numerical simulation model was established to verify the ability of proposed V/H model for predicting hardening behavior of TRIP steel in the large strain range. The results of the V/H model were compared with the original Voce and Hollomon models and experimental results. It shows that compared with normal Voce and Hollomon models,the V/H model can better reproduce the hardening behavior of TRIP steel after strain path change, and has a higher precision in predicting the fracture elongation.
一种考虑应变路径变化的TRIP钢组合硬化模型
[J].
A long short-term memory-based constitutive modeling framework for capturing strain path dependence in plastic deformation
[J].
A mixture of experts approach to handle ambiguities in parameter identification problems in material modeling
[J].
On the potential of recurrent neural networks for modeling path dependent plasticity
[J].
Using neural networks to represent von Mises plasticity with isotropic hardening
[J].
Machine learning-based constitutive model for J2- plasticity
[J].
Research progress on anisotropic fracture models and fracture tests for sheet metals
[J].The recent research progress on anisotropic fracture models and fracture tests for sheet metals was analyzed and overviewed. It is indicated that the meso-damage mechanics model incorporates the anisotropic damage evolution by accounting for the effects of plastic anisotropy, void shape, size and spacing. The continuum damage mechanics (CDM) model is extended to anisotropic CDM model by expressing the scalar phenomenological damage as a tensorial damage variable; for uncoupled anisotropic fracture models, anisotropic fracture is described by altering the measurement method of equivalent plastic strain increment or through the linear transformation of the stress tensor. The fracture tests under various stress states can be obtained by designing a series of specimens with different shapes or applying different combinations of loads at the specimen boundary. Besides, to design new out-of-plane specimens and set up relevant out-of-plane test is an important trend for sheet metals in the future.
金属板料各向异性断裂模型及断裂实验研究进展
[J].
Path-dependence of the forming limit stresses in a sheet metal
[J].
Prediction of sheet forming limits with Marciniak and Kuczynski analysis using combined isotropic-nonlinear kinematic hardening
[J].
Ductile damage evolution under cyclic non-proportional loading paths
[J].
Prediction of damage and hot forming limit of TA32 titanium alloy based on crystal plasticity model
[J].Forming limit diagram (FLD) is a crucial tool for assessing the formability of sheet metals under various forming conditions. However, conducting FLD experiments can be challenging and time-consuming requiring numerical determination of FLDs. Marciniak-Kuczyński (M-K) theory is one of the most well-known instability criteria for calculating forming limits, and the rapid development of crystal plasticity models provides a feasible framework for better understanding the relation between flow localization and material microstructure. Therefore, integrating the M-K theory with advanced crystal plasticity models offers a potential approach to precisely predict forming limits and explore the complex interaction between material behavior and microstructural characteristics. In this study, a crystal plasticity finite element (CPFE) model considering damage evolution was developed based on the microstructure and crystal orientation of a TA32 titanium alloy sheet. The material parameters for the proposed model were calibrated through uniaxial tensile tests and microstructure characterization. The internal correlation between damage evolution and the dislocation slip mechanism under different strain paths was analyzed at the grain scale. Additionally, the FLD of the TA32 sheet at 750 oC was predicted by coupling the CPFE model with the M-K theory. The results show that the proposed CPFE model accurately predicts the macroscopic mechanical response, microscopic inhomogeneous deformation, and damage evolution behavior of the TA32 sheet under different strain rates at 750 oC. The difference in the deformation behavior and damage propagation was mainly attributed to the anisotropic activation of various slip systems. The basal and prismatic slip systems of the basal bimodal texture in the original sheet were difficult to be activated under different strain paths, making it easier to induce damage than the transverse texture. The FLD predicted by the CPFE-M-K coupling model agrees well with the Nakazima test results, accurately capturing the decrease in the limit of major strain near the equibiaxial tensile region. This decrease is closely related to the anisotropy of the mechanical properties of the material. Furthermore, the change in the initial inclination angle of the groove in the CPFE-M-K coupling model considerably affects the prediction accuracy of the forming limits of the TA32 sheet. The critical initial inclination angles within the strain increment ratio ranges of -0.5-0.5 and 0.6-1.0 are 0° and 90°, respectively.
基于晶体塑性模型预测TA32钛合金损伤及高温成形极限
[J].晶体塑性模型将金属材料的塑性变形与微观组织演化相统一,为更好地理解钛合金高温复杂变形机制和预测不同应变路径下的成形极限提供了一种强有力的工具。本工作基于TA32钛合金板材的微观组织及晶体取向建立了一种考虑损伤演化的晶体塑性有限元(CPFE)模型,并通过耦合CPFE模型与M-K凹槽理论预测了TA32板材在750 ℃下的成形极限图(FLD)。结果表明,所提出的CPFE模型准确地预测了TA32板材在750 ℃不同应变速率下的宏观力学响应、微观非均匀变形和损伤演化行为。在不同应变路径下,原始板材中基面双峰织构的基面滑移系和柱面滑移系均难以被激活,导致其比横向织构更容易诱导损伤。采用CPFE-M-K耦合模型预测的FLD与实验结果吻合良好,并准确捕捉到了等双轴拉伸区域附近极限主应变降低的现象,分析表明其与材料力学性能的各向异性密切相关。此外,CPFE-M-K耦合模型中凹槽初始倾角的改变会显著影响TA32板材成形极限的预测精度,应变增量比为-0.5~0.5和0.6~1.0范围内的临界初始倾角分别为0°和90°。
Physics-guided machine learning for forming-limit assessments of advanced high-strength steels
[J].
Strain rate and temperature dependent fracture of aluminum alloy 7075: Experiments and neural network modeling
[J].
Prediction of ductile damage evolution based on experimental data using artificial neural networks
[J].
Modeling of {10-12}-{10-12} secondary twinning in pre-compressed Mg alloy AZ31
[J].
Predicting deformation behavior of α-uranium during tension, compression, load reversal, rolling, and sheet forming using elasto-plastic, multi-level crystal plasticity coupled with finite elements
[J].
Microstructure evolution of stainless steel subjected to biaxial load path changes: In-situ neutron diffraction and multi-scale modeling
[J].
A crystallographic dislocation model for describing hardening of polycrystals during strain path changes. Application to low carbon steels
[J].
Crystal plasticity modeling of prior austenite orientation effects on deformation behaviors of martensitic steels under different strain paths
[J].
A new ANN based crystal plasticity model for FCC materials and its application to non-monotonic strain paths
[J].
A theoretical and experimental study on forming limit diagram for a seamed tube hydroforming
[J].
Formability analysis of pre-strained AA5754-O sheet metal using Yld96 plasticity theory: Role of amount and direction of uni-axial pre-strain
[J].
Investigations of the effect of strain path changes on forming limit curves using an in-plane biaxial tensile test
[J].
Influence of the strain path changes on the formability of a zinc sheet
[J].
Advances in rolling-spinning technique of titanium tubes
[J].
钛合金筒形件轧-旋成形研究进展
[J].
Micromechanical behaviour of TA15 alloy cylindrical parts processed by multi-pass flow forming
[J].
A method to design the loading path for tube hydroforming process
[J].
一种管件液压成形加载路径的设计方法
[J].
Optimization of loading path in hydroforming T-shape using fuzzy control algorithm
[J].
Loading path optimization of tube hydroforming process
[J].
Process analysis of biconvex tube hydroforming based on loading path optimization by response surface method
[J].
Microstructure and superior mechanical properties of a multi-axially forged WE magnesium alloy
[J].
Study on the high-performance forming mechanism of TB6 titanium alloy shaped charge liner through controllable strain path forging
[D].
TB6钛合金药型罩可控应变路径锻造高性能成形机理研究
[D].
Method for pre-treating and matching reversing large deformation refined titanium alloy microstructure
[P].
一种预处理匹配换向大变形细化钛合金微观组织的方法
[P].
Study on generating rolling method for manufacturing cylindrical parts with external cross ribs
[J].
Comparative investigation of deformation mechanisms in Ti-6Mo-3.5Cr-1Zr metastable β titanium alloy subject to cold rolling strain paths
[J].
Rolling texture and its effect on tensile property of a near-α titanium alloy Ti60 plate
[J].
Effects of strain path on the microstructure, tensile properties, and formability of Al/Mg roll-bonded sheets
[J].
Multi-directional loading rotary extrusion forming technology and equipment
[J].Large thin-walled and high-ribbed components are typical structural components to achieve extreme light weight of products, and there are many challenges in their overall forming. In view of the demand for accurate plastic forming of high-performance large thin-walled lightweight components with inner ring high ribs, the new technology of multi-directional loading rotary extrusion forming technology is proposed for the first time, which can match linear motion of punches with rotational motion of dies and can actively increase the strong shear deformation of metal material. And a 12.5 MN-0.4 MN·m-10 r/min multi-directional loading rotary extruder with independent intellectual property rights is developed. By actively controlling the multi-stage combination of axial, radial and rotational movements of the mold, the equipment uses the micro-zone cumulative strain method to subvert the tradition that the shape of the blank and the workpiece determine the degree of deformation. This technology can control the orderly and reasonable flow of metal, realize the uniform toughness of material and the overall accurate forming of transverse high-ribbed members (0-70 mm in rib height) within thin walls, thus improving the mechanical properties and material utilization of products. This technology and equipment fills the gap of integrated and controlled forming of large thin-walled internal transverse high rib type lightweight components at home and abroad, and expands the new field of plastic forming.
多向加载旋转挤压成形技术及装备
[J].大型薄壁高筋构件是实现产品极限轻量化的典型结构件,其整体成形存诸多难题。针对高性能大型薄壁内环高筋类轻质构件精确塑性成形的需求,首次提出了将直线运动与旋转运动相匹配,主动增加强剪切变形的多向加载旋转挤压成形新技术,并开发出了具有自主知识产权的12.5 MN-0.4 MN·m-10 r/min多向加载旋转挤压机。该装备通过主动控制模具的轴向、径向以及旋转运动多级组合,利用微区累积应变颠覆了毛坯与工件形状决定变形程度的传统。利用该技术能控制金属的有序合理流动,实现材料的均匀强韧化和薄壁内环高筋构件(筋高0~70 mm)的整体精确成形,从而提高了产品的力学性能和材料利用率。该技术与装备填补了国内外大型薄壁内环高筋类轻质构件形性一体化控制成形的空白,拓展了塑性成形新领域。
Influence of ECAP deformation routes on grain refinement, mechanical properties and texture of zinc
[J].
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