0Cr16Ni5Mo1马氏体不锈钢奥氏体化动力学研究

采用膨胀试验研究了0Cr16Ni5Mo1马氏体不锈钢以0.05～10℃/s的速率连续加热时的相变动力学。结果表明:随着加热速率的增大,奥氏体化温度显著升高。利用杠杆定律计算获得了0Cr16Ni5Mo1钢中奥氏体生成量与加热温度之间的关系,采用Johnson-Mehl-Avrami (J-M-A)方程描述了钢的奥氏体化过程,并对相变动力学参数进行了拟合,得到奥氏体化相变激活能Q约为3.737×10~5 J/mol,J-M-A 指数n约为 0.905 43,指前因子 lnk_0约为 40.731,确定了0Cr16Ni5Mo1钢的奥氏体化动力学模型。基于非等温J-M-A方程绘制了等温奥氏体化动力学曲线和TTA (time-temperture-austenite transfor mation)图,可用于计算形状复杂零件连续加热的奥氏体化过程。     

加热速度对高Cr铁素体耐热钢奥氏体化动力学的影响

通过高精度差分膨胀仪记录了高Cr铁素体耐热钢在不同的加热速度(10,100,500,2000℃/min)下的线膨胀量,获得其在奥氏体化过程中的相关动力学信息,并利用等时转变动力学模型解析式拟合了试样在奥氏体化过程中奥氏体的转变体积分数随温度变化的实验曲线.根据动力学参数的拟合结果得出,在连续加热过程中,奥氏体晶核的形成以及其随后的长大过程分别主要由碳原子在铁素体中和奥氏体中的扩散所控制.     

基于ABAUQS-Matlab对42CrMo钢表面感应淬火奥氏体化参数的研究

目的 确定42CrMo钢感应淬火过程的奥氏体相变动力学参数，并验证其可靠性。方法 根据不同加热速率下42CrMo钢奥氏体膨胀曲线，基于经典JMAK（Johnson-Mehl-Avrami-Kolmogorov）模型和Kissinger方法，确定了42CrMo钢奥氏体化相变动力学的参数。建立ABAQUS局部移动式感应淬火模型，选取淬火区域加热过程中点的温度变化曲线作为验证奥氏体化模型的对象。基于Scheil法则和JMAK相变动力学模型，采用文中求解得到的奥氏体化参数，采用Matlab对42CrMo连续转变过程离散为每个时间间隔的等温相变并求解，并对照相关学者采用的扩展解析动力学模型和JAMK模型，加以验证。结果 根据上述方法，得到的42CrMo奥氏体相变动力学参数为：激活能Q为2.04×106 J/mol，指前因子lnk0的值取230.78，Avrami指数n取0.427。将淬火加热过程离散为数量很大的均匀时间间隔，并以求解的动力学模型在每个间隔内进行对应温度条件下奥氏体体积分数的求解并顺次叠加，以模拟得到的奥氏体转变时间和转变温度等作为依据，该模型有良好的表现性。结论 对42CrMo非等温且加热速度不恒定的连续奥氏体转变过程，JAMK模型拟合表现良好，采用文中求解的参数组对表面感应淬火的奥氏体转变历程进行仿真预测是可行的。     

低压转子用钢奥氏体化过程的预测

通过实验和相变动力学方法对30Cr2Ni4MoV钢在连续加热过程中的奥氏体化过程进行了研究。结果表明,奥氏体化的相变激活能Q和相变动力学参数n,k0分别为2.358×106J/mol,0.2501和269.8。通过拟合得到的奥氏体化曲线与实验结果吻合较好,并且对该钢在加热过程中的等温转变曲线进行了预测。     

42CrMo钢加热时奥氏体晶粒长大演化规律

对42CrMo钢在不同加热温度(850~1150℃)和保温时间(0~1200 s)下的奥氏体晶粒长大规律进行了研究。采用金相定量法对加热后材料的奥氏体晶粒度进行测量,建立42CrMo钢加热时奥氏体晶粒长大演化模型。结果表明:奥氏体晶粒尺寸随加热温度升高呈指数关系长大,随保温时间的延长呈近似抛物线形式长大;利用基于唯象理论的Sellars模型,通过非线性回归方法建立42CrMo钢加热时奥氏体晶粒长大演化模型;将该模型导入有限元软件中预报42Cr Mo钢加热时奥氏体晶粒变化,预报结果与实验结果吻合,验证了该模型的正确性。     

25Cr2Ni3Mo钢热力学及相转变计算

利用材料热力学与动力学模拟软件JMatpro对25Cr2Ni3Mo钢进行相变热力学和动力学计算,通过计算得到了25Cr2Ni3Mo钢的温度-相组成图、等温转变曲线(TTT)、连续转变曲线(CCT)、热力学函数随温度变化情况以及再奥氏体均匀化的温度和时间。模拟结果可为25Cr2Ni3Mo钢在动力学的数值模拟及生产工艺的制定等方面提供依据。     

基于计算机仿真的30Cr2Ni4MoV钢奥氏体化动力学分析

试验测得了不同加热速率下30Cr2Ni4MoV钢的奥氏体化曲线,确定了J-M-A模型中的参数,并对该模型在变温相变条件下进行动力学分析。结果表明,J-M-A模型对奥氏体化相变过程的预测结果与实验结果基本一致,表明J-M-A方程能够准确描述30Cr2Ni4MoV钢的非等温以及等温奥氏体化过程。     

5CrNiMoV钢的奥氏体化动力学预测

利用DIL-805ADT动态热膨胀相变仪测定5CrNiMoV热作模具钢在不同加热速率下的膨胀量并对膨胀曲线数据进行分析,运用Kissinger方法拟合出了非等温扩散相变动力学Johnson-Mehl-Avrami(J-M-A)模型中的奥氏体化相变激活能Q、相变参数n和lnk₀,建立5CrNiMoV钢奥氏体化动力学模型。该模型计算所得的奥氏体转变量与试验测量结果相吻合,可用于预测等温奥氏体化动力学曲线和设计5CrNiMoV钢的奥氏体化工艺过程。     

CrMo钢比热与热扩散系数的热力学估算

利用热力学亚点阵等模型,构建了Fe-Cr-Mo-C四元合金系中单相组织比热与热扩散系数的计算方法,并对20Cr Mo钢与42Cr Mo钢中奥氏体(fcc)和马氏体(bcc)等微观组织的比热与热扩散系数进行了计算与实测。计算与实测结果具有较好的一致性,由此表明本文计算方法能够较为准确的预测不同碳含量Cr Mo钢材料中奥氏体等微观组织在不同温度条件下的比热和热扩散系数。该方法可以简化比热与热扩散系数的实测工作,为Cr Mo钢零件的热处理(特别是渗碳热处理)数值模拟的开展提供参数保障。     

50Cr5NiMoV钢奥氏体分解动力学模型建立与应用

测量了50Cr5NiMoV钢的等温膨胀曲线,研究了等温膨胀曲线中孕育期的读取误差对拟合相变动力学参数n的影响,提出了一种获得参数n的方法,建立了50Cr5NiMoV钢的等温奥氏体分解相变动力学模型。应用叠加原理预测连续冷却条件下奥氏体分解相变体积分数,借助连续冷却膨胀曲线对模型参数进行了验证。同时,利用该模型,基于商用ABAQUS软件,对50Cr5NiMoV支承辊热处理过程进行了温度-组织模拟。研究结果表明,该模型能够准确地预测支承辊热处理过程中显微组织演变规律。     

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.