基于BP人工神经网络的TC17钛合金显微组织-力学性能关系预测

钛合金的性能对其组织状态十分敏感，与组织的多种显微特征呈现非线性的交互关系。本研究在定量分析钛合金显微组织的基础上，采用BP人工神经网络方法建立了TC17钛合金组织与力学性能的关系模型。该模型输入的显微组织特征参数包括：α相体积分数、α相厚度和不同形态α相的体积分数，输出的力学性能包括抗拉强度、屈服强度、延伸率和断面收缩率。结果表明，该模型具有很好的预测精度和泛化能力。应用贝叶斯正则化和动量梯度下降学习法较好地解决了传统BP人工神经网络训练高精度和预测低精度的过拟合现象。此模型的建立对构建TC17合金利用组织预报力学性能的专家知识库具有重要作用，而且对钛合金专家系统的整体开发具有重要指导意义。     

TC4 ELI钛合金的热变形行为及本构关系研究

利用Gleeble-3500热模拟试验机对TC4 ELI钛合金在两相区温度为750~950℃、应变速率为0.001~70s-1条件下进行等温恒应变速率压缩试验,分析了该合金的热变形行为,并采用Arrhenius方程和BP人工神经网络模型建立了该合金的本构关系模型。结果表明,应变速率与变形温度对TC4 ELI钛合金流变应力影响显著,流变应力随变形温度升高和应变速率降低而降低;在两相区热变形时,原始组织α相发生了不同程度的球化/动态再结晶,并且低应变速率会促进球化/动态再结晶的发生;采用Arrhenius方程和BP人工神经网络模型建立的本构方程平均误差分别为17.51%和1.36%,BP人工神经网络模型具有更高的精度,更适合用于TC4 ELI钛合金的流动应力预测。     

(α+β)两相钛合金显微组织的定量分析和表征

基于体视学方法,结合计算机图形处理,建立一套钛合金显微组织定量测量和表征的方法.对钛合金中片层和等轴两类典型组织进行定量表征,其参数包括:片层α的厚度、体积分数、形态、取向,初生α相尺寸、体积分数,总α相体积分数.分析实例表明,建立的钛合金显微组织定量表征方法精度高、重现性好,为后续建立显微组织-力学性能预测模型奠定了基础.     

钛合金显微组织与性能定量关系的模型

提出利用软计算方法定量分析钛合金显微组织与性能的关系。在实现钛合金显微组织的定量分析和参数化表征的基础上,探讨以钛合金显微组织特征参数为输入变量、以性能为预测输出变量的组织与性能定量关系模型的构建方法。依据长期实践中得到的组织影响性能的定性规律及热加工工艺对组织特征的影响程度,提出定量关系模型显微组织信息预处理过程中组织特征参数评价取舍原则。运用人工神经网络建立Ti-17合金组织与室温拉伸力学性能的定量关系模型,研究建模的具体方法。该模型对各项性能指标具有较高的预测精度,说明提出的建模思想合理和模型构建方法可行     

Ti-6Al-4V钛合金网篮组织与拉伸性能 定量关系研究

建立钛合金显微组织-拉伸性能定量关系对于组织性能的控制及优化具有重要意义。本文基于定量金相学和体视学原理,利用多元非线性回归方法建立了Ti-6Al-4V钛合金网篮组织-拉伸性能定量关系模型。模型自变量包括片状α相厚度、片状α相长宽比,因变量为合金的室温拉伸性能。经验证表明,所建立的多元回归模型对合金的拉伸性能具有较高的预测精度,说明模型的构建方法是可行的。     

TC4/TA17异种钛合金激光焊接接头显微组织和力学性能

研究TC4/TA17异种钛合金激光焊接接头的显微组织和力学性能。结果表明,TC4/TA17异种钛合金激光焊接头焊缝的显微组织为片状α′马氏体,TC4侧靠近母材的热影响区和TA17侧靠近母材的热影响区只发生α相向β相转变,TC4侧靠近焊缝的显微组织为残余α相+针状α′马氏体,TA17侧靠近焊缝的显微组织为残余α相+片状α′马氏体。TC4/TA17异种钛合金激光焊接头的显微硬度呈不对称分布,焊缝的显微硬度最高,TA17母材显微硬度最低。TC4/TA17异种钛合金激光焊接接头断裂在TA17母材,断口呈现韧性断裂形貌。     

热处理工艺对TA17钛合金板材组织与性能的影响

文章实验研究了热处理工艺对TA17钛合金板材显微组织与室温力学性能的影响。结果表明:TA17钛合金板材经过不同温度热处理时,合金板材的显微组织由等轴球状α相+晶间β相构成。随着温度升高,合金中的初生α相含量显著减少,并逐渐趋于等轴化,β相和次生α相的体积分数逐渐增大。在740780℃范围内热处理,强度与塑性匹配最好,得到的TA17钛合金板材综合力学性能最优。     

基于BP神经网络的TC11钛合金工艺-性能模型预测

材料工艺与性能的关系具有复杂、非线性交互等特点。本文根据TC11钛合金力学性能与其影响因素之间的映射关系,以大量的试验数据为基础,建立了BP神经网络模型。模型的输入包括锻造温度、锻后冷却方式等热加工工艺参数;输出为常用的力学性能指标,即抗拉强度、屈服强度、延伸率和断面收缩率。运用该模型对TC11钛合金力学性能进行了预测,并通过试验数据对模型的预测精度进行了可靠性验证。同时,运用已建立的神经网络模型对TC11钛合金工艺参数与力学性能的关系进行了分析。结果表明,所建立的力学性能预测模型具有良好的外推能力,并且可以很好地反映出该合金的工艺-性能之间的复杂关系。     

热处理对异质钛合金线性摩擦焊接头组织和显微硬度的影响

研究焊后热处理对TC4和TC17异质钛合金线性摩擦焊接头显微组织的影响。焊态条件下焊缝组织为完全再结晶组织,表明线性摩擦焊接过程中,摩擦界面温度超过β相变点温度,其中TC4侧焊缝组织主要为具有马氏体组织结构的α′相,TC17侧焊缝组织主要为单一的β相。TC4与TC17侧热力影响区组织为严重的变形组织,且具有明显的方向性,但在该区各相的体积分数未发生变化。热处理后,TC4侧焊缝组织中α′转变为针状的α＋β相,且随着热处理温度的升高,针状α相粗化,长大现象明显,并导致该区的显微硬度下降。TC17侧焊缝组织热处理后从晶界和β晶粒内部析出了细小的α相,导致该区显微硬度明显提高。     

冷却速率对TC16钛合金显微组织和力学性能的影响

利用XRD、SEM、TEM和力学试验机等手段分析不同冷却速率的TC16钛合金试样的相组成、显微组织和力学性能,并分析冷却速率对TC16钛合金显微组织和力学性能的影响。结果表明:TC16钛合金经800℃保温处理后,水淬和空冷试样均由α相、α″马氏体、ω相和β相组成,炉冷试样仅由α相和?相组成;水淬和空冷试样中的初生α相体积分数和晶粒尺寸都相近,均比炉冷试样的小。水淬和空冷试样的单向拉伸曲线上,出现双屈服现象;随着冷却速率的降低,TC16钛合金的屈服强度提高;水淬和空冷试样的抗拉强度相近,高于炉冷试样的;3种冷却速度试样的伸长率和断面收缩率相近,都具有优异的室温塑性。     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

Effect of Short-Time Aging on the Pitting Corrosion Behavior of a Novel Lean Duplex Stainless Steel 2002

The effect of short-time aging in the temperature range between 400 and 1000 °C on the pitting corrosion behavior and mechanical property of a novel lean duplex stainless steel(LDSS) 2002 was investigated through the potentiostatic critical pitting temperature(CPT) tests and the Charpy impact tests. Both the pitting corrosion resistance and the toughness of aged specimens degraded due to the precipitation of detrimental secondary phases and the most significant reduction of CPT and impact energy emerged at 650 °C concurrently. The CPT of LDSS 2002 specimen aged at 650 °C decreased by 28 °C, and the impact energy dropped from 69 to 29 J/cm~2 compared with the solution-annealed sample. Transmission electron microscopy characterization showed that the main precipitates in LDSS 2002 were Cr_2N and M_(23)C_6 along the ferrite–austenite grain boundaries.     

Information for Contributors

正The Transactions of Nonferrous Metals Society of China,founded in 1991 and sponsored by The Nonferrous Metals Society of China,is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology,including mineral processing,extraction metallurgy,metallic materials and heat treatments,metal working,physical metallurgy,powder metallurgy,with the emphasis     

Preface

<正>We are pleased to present this Special Issue of Transactions of Nonferrous Metals Society of China containing selected papers from the First Asian Conference on Aluminum Alloys(ACAA-2013),held in Beijing,China,13–17 October 2013.This conference has been initiated,with approval of     

Information for Contributors

The Transactions of Nonferrous Metals Society of China, founded in 1991 and sponsored by The Nonferrous Metals Society of China, is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology, including mineral processing, extraction metallurgy, metallic materials and heat treatments, metal working, physical metallurgy, powder metallurgy, with the emphasis on fundamental science. It is the unique preeminent publication in English for scientists, engineers, under/post-graduates on the field of nonferrous metals industry. This journal is covered by many famous abstract/index systems and databases such as SCI Expanded, Ei Compendex Plus, 1NSPEC, CA, METADEX, AJ and JICST.     

INTRODUCTION TO PATENTS

The invention provides a method of making a mold which can reduce SOx generation rate while preventing decrease in hardening rate in the case of using sulfuric acid for a hardener composition. The method has a mixture step in which fire-resistant particles, a hardener composition and a binder composition are mixed to obtain a composition for a mold. The hardener composition contains sulfuric acid. In the mixture step, sodium carbonate is added. A molar ratio of the sulfuric acid to the sodium carbonate is 0.5 or more and 4.0 or less.     

China Foundry Week 2014

China Foundry Week, hosted by the Foundry Institution of Chinese Mechanical Engineering Society （FICMES） each year, is a large academic event in China. It is one of the ten high-impact activities sponsored by the Chinese Mechanical Engineering Society.     

17th Conference of Hydrodynamic and Electromechanical Control Engineering Call for papers

正1.Contents In order to promote the academic exchanges and technical communication of the research in the field of fluid power transmission and control,fluid control engineering specialized committee of the Chinese Society of Theoretical and Applied Mechanics will hold the 17th Conference of Hydrodynamic and Electromechanical Control Engineering on July 27-29,2014 in Tibet,Lhasa city.     

Formulas of Tension of Continuous Rolling Process

The development of computer controlled continuous rolling process calls for a mathematical expression that can express the inequality condition of "constant flow". Tension is the link of the continuous rolling process. From the condition of dynamic equilibrium, a differential equation of tension is given out. On the basis of the physical rules established from the industrial practice and experimental studies, the law of volume constancy, the linear relation of forward slip and tension, the state equation of continuous rolling, the formula of dynamic tension, and the formula of static tension have been obtained. These formulae reflect the functional relations between tensions, thickness, roll velocity, and time in the continuous rolling process. It is implied that the continuous rolling process is a gradually steady, controllable, and measurable dynamic system. An assumption of predicting the thickness of a steel plate using these tension formulae is also put forward.