Optimizing Domain Distribution of Grain Oriented Silicon Steel by Using Antimony as the Laser Surface Alloying Element

For reducing the core loss of grain oriented silicon steel and improving its aging property, a new method, the LLSA by using Sb as the laser surface alloying element, was investigated, and at proper technique conditions rather good result was obtained.

Study of the Coarse Blocky Compounds in the As－cast 7075 Aluminium Alloys Containing Rare Earth Elements

The coarse blocky compounds in the as-cast 7075 aluminium alloys containing rare earth elements, neodymium, cerium or mischmetal were investigated by means of transmission electron microscope with EDX and scanning electron microscope. The blocky compounds in these alloys were identified as rare earth compounds, (Cr, Ti)2 RE (Al, X)20 (X is magnesium, copper and zinc),body-centred cubic, with 184 atoms to the unit cell , lattice parameter 1.453￣1. 458 nm, Vickers hardness 4000￣5600 MPa and calculated density 3400 kg/m3. The results show that the amount of blocky compounds in the alloys decreases with decreasing of Ti and Cr content or with increasing of cooling rate during solidification.

Effect of pulsed current on temperature distribution,weld bead profiles and characteristics of gas tungsten arc welded aluminum alloy joints

Temperature distribution and weld bead profiles of constant current and pulsed current gas tungsten arc welded aluminium alloy joints were compared. The effects of pulsed current welding on tensile properties, hardness profiles, microstructural features and residual stress distribution of aluminium alloy joints were reported. The use of pulsed current technique is found to improve the tensile properties of the weld compared with continuous current welding due to grain refinement occurring in the fusion zone.

Influence of viscous medium temperature distribution on sheet fracture in viscous pressure forming at warm temperature

Viscous pressure forming(VPF) of aluminum alloy AA3003 sheet metal at warm temperature was investigated by using coupled thermo-elastoplastic-viscoplastic finite element method. The influence of viscous medium temperature distribution on sheet fracture location was studied and the distributions of fracture factor at different temperatures were obtained by using ductile fracture criterion. The results show that the failure of sheet metal varies with increasing initial temperature of viscous medium. When the initial temperature of viscous medium is near that of sheet metal,the failure location occurs at dome center,and when the initial temperature of viscous medium is too low,however,the failure location occurs at die corner. The occurrence of fracture can be postponed and even prevented through controlling the temperature distribution in viscous medium.

Investigation on Behavior of Rare Earth Element Cerium in Aluminum-Lithium Alloys by Internal Friction Method

The behavior of rare earth element Ce in 2090 Al Li alloys was studied by the method of low frequency internal friction.The results showed that rare earth element Ce can increase the activation energy of grain boundary and improve the grain boundary strength of alloys.Rare earth element Ce can decrease the tendency of softening of elastic modulus of 2090 Al Li alloys after heat cycle and keep high elastic modulus of initial state.

Residual Stress Distribution of Asymmetric Quenching in Al-Zn-Mg-Cu Aluminum Alloy Plate

The residual stress distribution for two strategies of asymmetric quenching in Al-Zn-Mg-Cu aluminum alloy plates has been simulated using the finite element method. The results show that for asymmetric quenching between the upper and lower surfaces, the through-thickness asymmetric quenching residual stress distribution lies between the two distributions corre-sponding to the heat transfer coefficients on the upper and lower surfaces respectively. The surface and central stress magnitudes are equal to the average of the stress magnitudes corresponding to the two heat transfer coefficients. For asymmetric quenching of a single surface, the surface stress distribution is the same as the heat transfer coefficient distribution and the stress magnitude is equal to the stress magnitude corresponding to the average value of the heat transfer coefficients at each location. However, the center quench residual stress distribution is approximately uniform and the stress magnitude is equal to the average of the stress magnitudes corresponding to the maximum and minimum heat transfer coefficients.

车用铝合金弯曲成形回弹行为研究进展

《中国制造2025》将轻量化列为众多关键行业发展的核心技术和共性技术,提高汽车轻量化能够有效节约油耗、减小排量、减轻对环境的污染,是汽车工业发展的必然趋势。铝合金材料由于其自身质量轻、易加工成型、节能、环保、回收率高等优势,被认为是汽车轻量化的首选材料。在实际应用过程中,为配合整体结构的装配,铝合金材料通常需要弯曲成一定的形状。但是弯曲成形回弹控制问题一直是该领域的研究难点。本文首先从成形方法、几何参数、材料参数、工艺参数等方面入手,将实验探究与有限元模拟相结合,讨论了这些因素对铝合金弯曲成形回弹的影响规律,揭示了这些因素对弯曲回弹的影响机理,为铝合金弯曲成形回弹行为的高精度控制提供了理论基础。另外,本文综述了铝合金弯曲回弹的预测及控制方法,并对铝合金弯曲回弹的现存问题进行总结归纳,有望对铝合金弯曲成形回弹行为的高精度控制提供新思路。

304LN表面沉积异质合金过程多组元传输行为数值模拟

目的探究在304LN不锈钢表面上激光沉积Stellite 6合金过程中的多元素传输机制。方法采用流体体积法VOF(Volume of Fluid),建立气-液两相传热传质激光沉积模型。模型中使用改进VOF法对熔池表面进行追踪,结合多组分传输模型与熔凝杠杆原则(Lever Rule),对异质材料熔覆界面的多元素传输进行模拟,采用扫描电子显微镜(SEM)与能谱仪(EDS)观察组织结构和元素分布,对比模拟结果分析多组沉积层宏观形貌和元素分布特征。结果沉积过程中,熔池的流动与材料导热对温度的传输起着重要作用,前端对流不断地将已熔化的基材金属运输至熔池中部,后端对流则将卷积的Fe元素和Co元素进一步混合。最终沉积层的宏观形貌平均误差为2.67%,主要元素Fe、Co、Cr的质量分数误差分别为0.64%、1.27%、0.31%。结论Fe元素浓度整体区域分布相对均匀,但在沉积层底部,Fe元素浓度迅速升高,Co元素浓度随沉积深度加深逐渐降低,Cr元素在沉积层中部富集的分布特性。该优化后的模型可以准确模拟异质合金沉积过程中的温度场、流场与质量传输过程。

大规格7A04铝合金铸锭裂纹缺陷的研究

采用电磁铸造法制备880 mm规格直径的7A04铝合金铸锭,通过工业CT扫描、SEM和EDS等检测分析手段研究了该铝合金铸锭中裂纹缺陷的形成原因和抑制措施,同时对缺陷附近区域微小缺陷的数量与分布进行了分析。结果表明,该铸锭出现裂纹的实质为Al_(2)O_(3)(氧化物)和少量Fe元素富集,位置靠近铸锭中心区域。观察微小缺陷其数量随半径尺寸的增大而略有减少,且大于40μm的缺陷占比最大。通过分析,微小缺陷的形成与裂纹缺陷的形成有关。在铸造前从合金熔体中去除夹杂物和气体氢,完善除气、扒渣等工艺过程是避免这些缺陷的方法。

5052铝合金板材渐进成形工艺参数双目标优化及试验验证

针对金属板材单点渐进成形工艺,选用具有较强成形性能的5052铝合金板材进行研究。基于Abaqus建立单点渐进成形有限元模型,以工具头直径、轴向进给量、板材初始厚度为研究变量,成形后圆锥台结构的最大Mises应力和最大减薄率为优化目标,设计了正交试验,并对每组参数进行模拟分析,采用田口分析和方差分析对工艺参数进行优化。优化结果表明,轴向进给量和板材初始厚度是对最大Mises应力影响的显著项,最终的优化工艺参数组合为工具头直径8 mm、轴向进给量0.5 mm、板材初始厚度0.5 mm,该工艺参数分析的圆锥台结构最大Mises为213.35 MPa,最大减薄率为38.32%。通过单点渐进成形试验进行验证,成形后的圆锥台结构表面质量较好,这也表明该工艺参数组合具备实际应用的可行性。

铝合金在接触固溶处理工艺中的界面传热系数

采用有限元模拟和反演优化(IO)方法测定7075铝合金在不同压力、表面粗糙度和温度下接触固溶处理过程中的界面传热系数(IHTC)值,并分析这些因素对IHTC的影响。结果表明:随着压力的增加,IHTC值先增加,然后保持稳定;IHTC值随表面粗糙度的增大而减小;随着板温的升高,瞬时IHTC值先增大后减小。基于压力、表面粗糙度和温度的综合影响规律,建立多因素影响的IHTC理论模型。使用此模型能较好地预测不同条件下合金的瞬时IHTC值。

铝合金硬质阳极氧化关键工艺中的有限元分析

[目的]结构复杂的2A11铝合金零件在整体硬质阳极氧化时易出现烧损、膜层均匀性较差等问题。[方法]基于AnodizingManager阳极氧化仿真技术,采用有限元分析方法对典型工艺方案进行仿真计算,并基于仿真结果开展优化试验方案设计。[结果]经试验验证,通过构建新型遮蔽物与导电点,可以改善硬质阳极氧化零件表面氧化膜厚度的均匀性,提高产品合格率。[结论]对于复杂结构的铝合金硬质阳极氧化,数值模拟技术是完全可行的,其应用彻底改变了传统工艺优化的“经验设计——现场试制——纠错”研发模式,可节省大量的时间与成本。

深海浮标反应舱的设计与有限元仿真

为了帮助极地深海设备平台解决穿透冰层的问题,深海浮标上搭载了一种反应舱加热装置。该装置是一个封闭式圆筒化学反应容器,其四周是外径为180 mm的铝合金筒体,上下底面采用端盖进行密封,并且内部穿插了各种管道。在设计方案基础上对反应舱进行耐压设计,采用SolidWorks软件和ANSYS Workbench软件对反应舱壳体进行结构设计及静力学有限元仿真分析。研究结果表明:该反应舱壳体的筒壁和端盖厚度均设计可靠,在水下375 m压力环境下工作时所受的等效应力和变形均在安全范围之内。

佛山市某大跨径铝合金人行天桥桁梁结构分析

铝合金作为一种优质的新型桥梁结构材料,具有轻质高强、易养护、低碳环保、施工便捷、景观性强等特点。近年来,铝合金结构在城市人行天桥中已被较多应用,但少有大跨径铝合金人行天桥应用实例。以佛山市禅城区佛山大道(澜石路口)人行天桥为例,详细介绍大跨径铝合金人行天桥上部结构设计。通过MIDAS及3D3S有限元模型,对大跨径铝合金人行天桥上部结构进行选型分析,可为大跨径铝合金人行天桥上部结构设计提供参考。

Modeling and characterization on electroplastic effect during dynamic deformation of 5182-O aluminum alloy

The coupling effects of electrical pulse,temperature,strain rate,and strain on the flow behavior and plasticity of 5182-O aluminum alloy were investigated and characterized.The isothermal tensile test and electrically-assisted isothermal tensile test were performed at the same temperature,and three typical models were further embedded in ABAQUS/Explicit for numerical simulation to illustrate the electroplastic effect.The results show that electric pulse reduces the deformation resistance but enhances the elongation greatly.The calibration accuracy of the proposed modified Lim−Huh model for highly nonlinear and coupled dynamic hardening behavior is not much improved compared to the modified Kocks−Mecking model.Moreover,the artificial neural network model is very suitable to describe the macromechenical response of materials under the coupling effect of different variables.

钛及钛合金外科植入物阳极氧化表面形貌及元素含量分布研究

目的探讨外科植入物产品阳极氧化表面元素含量分布及表面形貌分析,以促进产业优化,服务企业发展。方法采用扫描电镜及能谱仪对试样阳极氧化膜形貌和表面元素含量进行分析,并对各元素分布情况进行统计分析。结果着色阳极氧化产品表面形貌为不规则的凹凸不平状且均匀分布在氧化膜表面,其表面所含元素除基体元素外,有11.07%的产品表面包含Na、Si、P、S、Al等其他元素中一种或多种,且含量(质量分数)几乎全部落在小于1.00%这个区间。与着色阳极氧化产品相比,微弧阳极氧化产品表面形貌为均匀分布的火山口状突起,内部出现很多孔洞,直径为100~300 nm且出现交联,在整体上呈现立体孔隙结构,且表面所包含其他元素均匀分布在阳极氧化产品表面,其表面所包含元素除基体元素外,均还包含Na、Si、P、S、Ca、Mg、Fe等其他元素中一种或多种,且含量(质量分数)基本落在小于10.00%这个区间,其中Si、P含量落在1.00%~10.00%区间的批次占比均高于80%。结论研究结果显示不同企业、不同生产工艺的阳极氧化表面所含元素的种类和含量差异较大,但对优化改进企业生产工艺而言具有指导性意义,如企业应严格控制电解液的配方,且定期更换;电解池和清洗池的材料应与植入物产品基体材料相同;不同材料的产品应分开进行清洗;对于有意添加的元素(如Si、P、Ca等),其含量应尽量落在同一区间内,以确保作用最大化;而对于工艺引入的杂质元素,其含量应尽可能低,以降低不良反应发生的可能性。此结果对表面元素定量分析、生物安全性评价及临床应用也具有一定的参考意义。

铸铝合金螺旋弹鼓的车削数值模拟仿真与试验

为了研究螺旋弹鼓车削工艺技术,采用单因素试验、正交试验方法进行有限元仿真,采用极差分析方法分析刀具主要几何角度对切削力及刀尖温度的影响规律。通过切削加工试验对仿真结果进行验证。结果显示:当车刀前角为4°、后角为12°、刀尖圆弧半径为0.6 mm时,切削过程表现较好;有限元仿真软件可以较好地反映实际加工过程,可以为刀具参数的优化提供可靠依据。

高温合金H80A钢的Al、Ti元素控制技术研究

高温合金具有优异的高温力学性能、组织稳定性和抗热腐蚀性能,可在高温与复杂应力的环境长期可靠工作,广泛用于制造航空、航天、舰船发动机的热端部件。以高温合金H80A钢为例,分析真空熔炼和电渣重熔过程的Al、Ti元素变化规律,然后提出有效的Al、Ti元素控制措施。采取针对性措施后,H80A钢成分控制能力提高,产品质量大幅提升。

基于MeltFlow-VAR的Ti2AlNb合金铸锭熔炼工艺研究

在Ti2AlNb合金的熔炼过程中,成分均匀性受稳弧电流及周期、熔炼电流的影响波动范围较大,本文采用MeltFlow-VAR模拟软件对Ti2AlNb合金的熔炼流程进行了精确的模拟分析。在此基础上,我们确立了合理的熔炼电流、稳弧电流以及周期等关键工艺参数,以指导实际生产操作,显著提升了生产过程的可控性。所生产Ti2AlNb合金铸锭中Nb元素的分布呈现出均匀状态,且其化学成分的波动范围保持在较低水平。

X荧光光谱仪测定7×××系铝合金中元素的方法研究

通过电流、电压、计数时间等不同试验参数的正交试验,确定了X射线荧光光谱法的最佳试验条件。选择铝合金标准样品,建立标准工作曲线,实现了7×××系铝合金中元素Si、Fe、Cu、Mn、Mg、Cr、Ni、Zn、Ti、Zr的准确测定。对该测定方法的精密度进行考察,铝合金样品中各元素测定结果的相对标准偏差均低于0.7%,对标准样品进行分析,测定值与化学法吻合较好,能够满足铝合金各元素的准确测定的需求。