TC17线性摩擦焊界面温度分析与测量

焊接过程中的界面温度是研究接头组织形成变化机理的关键参量。根据线性摩擦焊接过程准稳定摩擦阶段焊件中（不包括飞边）准稳定温度场基本保持不变,所产生的热量主要被飞边带走的特点,通过理论分析,求解出了线性摩擦焊接过程准稳定摩擦阶段焊接界面的平均温度,利用半自然热电偶实际测量了TC17钛合金线性摩擦焊接时的焊接界面不同位置的温度变化。结果表明,典型参数下TC17准稳定摩擦阶段焊接界面的实测温度大约为1 228℃,焊后冷却至500℃的速度约52℃/s,准稳定摩擦阶段焊接界面中心点和边缘点的温度相差不超过10℃,界面中心点的升温速率以及降温速率均高于边缘点,测量值与理论计算值相差不超过10%。     

转速对TC4摩擦焊接头温度分布与微观组织的影响

采用连续驱动摩擦焊技术对TC4钛合金进行了连接。利用热电偶测温及金相显微镜观察等分别研究了不同转速下TC4钛合金焊接接头界面区的温度分布及微观组织变化。结果表明,焊接界面的升温速率和峰值温度均随转速增加而增大,初始摩擦阶段升温速率最高达762℃/s,峰值温度最高达1041℃,且转速越高,焊接界面温度沿径向分布的均匀性越好。TC4摩擦焊接头焊合区组织为网篮状组织,热力影响区为双态组织。网篮状组织随转速增加而明显粗化。     

边界散热条件对TC4线性摩擦焊接温度场的影响

基于ABAQUS软件建立了线性摩擦焊二维热力耦合数值模型,研究了边界散热条件对TC4钛合金线性摩擦焊接头温度场的影响。结果表明,在摩擦阶段,边界散热条件对TC4钛合金线性摩擦焊的接头最高温度及高温分布区域没有影响。在冷却阶段,边界散热条件对接头温度场呈现不同影响,在初始5 s内,边界散热条件对接头温度场几乎没有影响;在接头冷却5 s后,散热条件对接头温度场的产生了显著的影响,在冷却100 s时刻,A、B和C散热条件下接头最高温度分别为181℃、61℃和23℃。     

基于ABAQUS二次开发TC4线性摩擦焊过程的数值模拟

基于ABAQUS/Standard模块,建立TC4线性摩擦焊接过程的二维有限元模型,采用网格重划分与映射技术来处理网格畸变问题,分析线性摩擦焊接接头温度场的演变和轴向缩短量的变化.结果表明:网格重划分与映射技术能较好地解决网格畸变带来的计算不收敛.焊接过程的前0.1 s内,焊接界面温度迅速升高至1 000 ℃以上,之后接头温度渐趋均匀,接头塑性金属开始被挤出形成飞边,轴向缩短量明显增加;摩擦停止时刻(3 s),单边轴向缩短量达到最大值,约为2.7 mm.     

基于三维双塑性体摩擦副模型的FGH96高温合金管惯性摩擦焊数值模拟

基于弹塑性有限元理论,采用三维塑性体/塑性体摩擦副模型,考虑实际焊接过程中两侧工件散热条件的差异,建立了FGH96高温合金管惯性摩擦焊过程有限元模型,计算了焊接过程中瞬态温度场和轴向应力场的分布,研究了初始转速、顶锻力和转动惯量对接头温度场和飞边形貌的影响。模拟的飞边形貌与试验所得焊件误差仅为5%,验证模型的可靠性。模拟结果表明,惯性摩擦焊过程中,摩擦界面升温迅速,峰值温度可达1 335 ℃,塑性变形主要发生在距界面4 mm的区域内,该区域轴向温度梯度较大。摩擦界面附近压应力值从中心到边缘逐渐降低,界面边缘应力状态由压应力转变为拉应力,飞边根部由于挤压变形,存在压应力集中。提高初始转速和转动惯量均能增加焊接热输入,延长摩擦时间,提升峰值温度,增加飞边挤出量;加大顶锻力可提高机械能转化成热能的效率,缩短摩擦时间,增加轴向缩短量和飞边卷曲度。 创新点： 塑性体/塑性体有限元模型能够综合考虑接触面力的相互作用,采用更符合实际的三维双塑性体模型,对FGH96高温合金环形工件惯性摩擦焊过程进行了数值模拟。     

钢管径向摩擦焊温度场数值模拟

采用ABAQUS有限元软件,基于传热学及弹塑性力学有限元法,建立了径向摩擦焊接过程的二维轴对称、热力耦合及非耦合有限元计算模型.采用网格重划分技术模拟了径向摩擦焊接过程中焊接接头的温度场分布.结果表明,模拟出的接头飞边形貌与实际结果吻合良好.在二级摩擦阶段,摩擦界面由摩擦生成的热量与飞边形成带走的热量以及热传导散失的热量达到动态平衡,界面温度稳定在1320℃以下.在三级摩擦阶段,由于高温金属层被迅速挤出,界面温度迅速下降.通过分析金相组织,得出接头热循环过程.接头温度分布的模拟结果与实际结果吻合良好.     

45钢线性摩擦焊接过程的数值分析

基于Abaqus/Explicit显式有限元分析软件,建立了线性摩擦焊接同质接头的二维计算模型,研究了线性摩擦焊接45钢接头温度场、应力应变场、轴向缩短量和焊接后期接头的降温过程.结果表明,焊接界面中心温度可在不到1s内骤升至800℃,之后界面温度缓慢上升至900℃左右,随着焊接过程的进行,焊接接头主要是温度场的均匀化、不断的轴向缩短和飞边的形成,随后接头经历了较快的降温过程.试验验证了计算模型的可靠性.     

35Ni4Cr2MoA钢锻件连续驱动摩擦焊温度场及变形数值模拟研究

基于Abacus大型有限元分析软件,对35Ni4Cr2MoA空心轴环形工件连续驱动摩擦焊温度场和变形进行了模拟,对摩擦和顶锻阶段的温度场及变形规律进行了分析,并采用热电偶分析法对连续驱动摩擦焊工件表面的热循环进行了实测。结果表明,在摩擦阶段,最高温度在圆环外侧,随焊接时间增加,接触面温度不断升高,高温区域逐渐扩大,1260℃左右时界面金属发生屈服而形成焊接飞边,界面温度处于动态平衡,稳定在1260℃附近;在顶锻阶段,随时间增加,界面温度逐渐降低,高温区域缩小,温度在径向呈均匀分布,焊接飞边和轴向缩量均较摩擦阶段增大;在整个焊接过程中,界面各点温度先快速升高,后保持稳定,最后逐渐下降。热循环模拟结果与实测结果吻合较好,所建立的摩擦焊数值模型是可靠的。     

焊接参数对摩擦塞焊焊接区域温度场的影响

为了研究焊接参数对摩擦塞焊焊接区域温度场的影响,建立了摩擦塞焊焊接的产热模型,并进行摩擦塞焊焊接工艺试验。通过理论分析得出焊接过程中的产热量与焊接参数的关系,试验对理论分析结果进行验证,并深入探讨焊接参数对焊接区域温度场的影响。结果表明:焊接进给速度的改变影响焊接过程中的焊接压力大小,从而影响摩擦塞焊焊接初始阶段的产热,进而影响焊接区域温度场;较高的焊接转速提高摩擦界面材料的升温速率,提高材料塑化,避免焊接缺陷;应选择适当的焊接摩擦时间,尽量匹配较高的转速以缩短焊接摩擦时间。     

基于特征点测量的径向摩擦焊接温度场分布

介绍了半自然热电偶法测温原理,并对所选用的半自然热电偶进行了标定,线性度良好.采用自主研发的径向摩擦焊机进行径向摩擦焊接工艺试验.以摩擦焊接过程特点为依据,选择恰当的测温仪和热电偶.采用半自然热电偶对径向摩擦焊接过程中摩擦界面中心点温度进行了全过程测量;采用K型热电偶对管体侧距界面中线点纵向距离为1,2,3,6 mm的位置进行了温度测量.摩擦界面升温迅速,存在明显的温度恒定即稳定摩擦阶段.随着距摩擦界面纵向距离的增加,升温速率逐渐降低,升温时间逐渐增长.焊接过程结束后,温度逐渐趋于均匀化.     

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.     

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.     

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.     

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.