钛微合金化热轧TRIP钢的连续冷却相变研究

用Formastor-FII相变仪研究了钛微合金化TRIP在不同开冷温度下的连续冷却相变,建立了实验钢的连续冷却转变曲线,分析了铁素体、贝氏体及马氏体的相变规律.结果表明,随着冷却速率的增加,实验钢依次经过铁素体、贝氏体及马氏体相区,在较宽的冷却速率范围内,均可获得贝氏体及马氏体组织,其Ms点为450℃左右;随着开冷温度的降低或冷却速率的提高,实验钢的铁素体及贝氏体开始转变温度降低,抑制了铁素体及贝氏体相变;随着冷却速率的增加,实验钢的显微组织由铁素体+粒状贝氏体逐步转变为板条贝氏体+板条马氏体及板条马氏体组织;当冷却速率较低时,铁素体由晶内铁素体和晶界铁素体组成,晶内铁素体形核质点为复杂的氧化物及硫化物.     

淬火冷速对转子30CrMoNiV511钢韧性的影响

使用热处理风冷炉模拟研究了大型汽轮机转子内外径处的冷却速率对转子材料30CrMoNiV511钢的组织转变及强韧性的影响。结果表明,淬火冷却速率对转子材料的强度影响不明显,而对冲击韧性的影响显著。随着淬火冷却速率从50℃/min逐渐降低至7℃/min,淬火组织由下贝氏体逐渐向上贝氏体、粒状贝氏体及其混合组织转变,冲击韧性由66 J急剧降低到16 J;当冷却速率降低到5℃/min以下时,组织中出现先共析铁素体,且上贝氏体铁素体粗大,碳化物分布极不均匀,冲击韧性极差。不同冷却速率转子钢的微观组织及碳化物析出形态和分布是决定其冲击韧性的主要原因之一。     

奥氏体变形对铌微合金钢贝氏体相变的影响

用Gleeb le-1500热模拟机研究了铌微合金钢奥氏体变形后连续冷却条件下贝氏体相变规律.研究表明,随变形温度的升高,先共析铁素体量较少,贝氏体的板条束变宽.在连续冷却条件下,贝氏体的转变量随变形量的增加而减少,随应变速率的增加而减少,但应变速率对贝氏体转变量的影响随冷却速度的增加而减弱.随着变形后保温时间的延长,奥氏体稳定性增加,在较快冷却条件下转变产物中存在残余奥氏体.     

超低碳SiCrMn2Ni4钢连续冷却转变行为研究

研究了超低碳SiCrMn2Ni4钢钢连续冷却过程,采用金相显微镜、SEM和TEM对组织进行观察分析。结果表明,试验钢在连续冷却后,只存在粒状贝氏体和板条状贝氏体组织。随着冷却速度的加快,组织逐渐由粒状贝氏体向板条状贝氏体转变,当冷却速度增加至5℃/s时,出现粒状贝氏体与板条状贝氏体的混合组织,冷却速度大于等于20℃/s时,组织全为板条状贝氏体。     

连续缓慢冷却贝氏体转变特征及合金元素分布的影响

利用热膨胀仪对实验用预硬型塑料模具钢不同冷却速率进行热模拟,观察组织形貌,并用电子探针显微分析仪对不同组织区域进行定点分析,发现Mo,Si在抑制珠光体转变及粒状贝氏体转变过程中起重要作用.在冷速≤0.015℃/s 冷却条件下,组织转变较为复杂,转变过程中有珠光体出现.由于内部合金元素微观分布不均匀,贝氏体组织分为片状和...     

9Ni钢焊接热影响区组织转变规律的研究

采用热模拟技术研究了液化天然气储罐用9Ni钢焊接热影响区的组织转变规律。实验结果表明,9Ni钢经历热循环后的显微组织类型包括贝氏体和马氏体两种。低冷却速度条件下,9Ni钢经历热循环后的主要转变产物为贝氏体(包括粒状贝氏体和上贝氏体两种类型);随着冷却速度的提高,组织类型由粒状贝氏体向上贝氏体转化。高冷却速度条件下,经历热循环后的转变产物为马氏体。     

冷却速率对30CrNiMo8钢过冷奥氏体转变的影响

采用膨胀法结合金相检验和硬度测试,在相变膨胀仪上测定了30CrNiMo8钢的临界点温度,绘制了过冷奥氏体连续冷却转变曲线,研究了不同冷却速率对30CrNiMo8钢显微组织和硬度的影响。结果表明:当冷却速率为0.02~7℃·s~(-1)时,随着冷却速率的增加,30CrNiMo8钢的显微组织由粒状贝氏体为主逐渐转变为马氏体为主,硬度也逐渐升高;马氏体转变的临界冷却速率为1.0~1.5℃·s-1,30CrNiMo8钢的淬透性较好。     

冷却速度对10CrNi5MoV钢焊缝金属相变的影响

采用Gleeble-3500热模拟试验机测量了10CrNi5MoV钢焊缝金属在不同冷却速率下奥氏体连续冷却过程中的温度-膨胀曲线,利用杠杆定律,得到了不同冷却速率下相变动力学曲线,分析了冷却速率对焊缝金属相变的影响。结果表明,不同冷却速率下焊缝金属的奥氏体转变动力学曲线均呈S型,冷却速率为60 ℃/s、30 ℃/s、15 ℃/s时,奥氏体转变速率与温度的曲线呈单峰状,冷却速率为6 ℃/s,奥氏体转变速率与温度的曲线表现为贝氏体、粒状贝氏体相变的双峰转变。      

3Cr2Mo塑料模具钢连续冷却相变行为

为了调节塑料模具钢3Cr2Mo的组织,以实现在线预硬化,使用Gleeble1500热模拟试验机、光学显微镜以及透射电子显微镜等研究3Cr2Mo钢变形及未变形奥氏体的连续冷却相变行为及相变组织.实验结果表明,3Cr2Mo钢奥氏体稳定性较高,在所研究的实验条件下,连续冷却过程中没有出现先共析铁素体和珠光体,而是发生贝氏体和马氏体相变.热变形使奥氏体发生了机械稳定化,贝氏体相变推迟到较低温度下才完成.随着冷却速度的降低,贝氏体的形态由常规板条状变成粒状,最终可获得粒状贝氏体组织.     

控轧控冷工艺对高强度X100管线钢组织的影响

对一种X100管线钢进行热模拟试验,研究了过冷奥氏体的相变规律,提出了一种得到以粒状贝氏体+板条贝氏体为主的混合组织的控轧控冷工艺制度,分析了精轧变形量、冷却速度及终冷温度对实验钢微观组织的影响。结果表明,随着变形量的增大实验钢的微观组织逐渐细化,高强度的板条贝氏体含量减少而粒状贝氏体含量增多;随着冷却速度的增加和终冷温度的降低实验钢组织中的板条贝氏体含量明显提高,组织也逐渐细化;组织中板条贝氏体含量较高时实验钢具有较高的强度,但过多的板条贝氏体和针状M/A岛对材料的韧性造成不利的影响。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Synthesis of Alumina-Zirconia Nanocomposites by Solgel Process

Al₂O₃-ZrO₂ nanocomposites were developed starting with the solgel process. Composite alumina-zirconia nanopowders were synthesized from metallorganic precursors (Aluminium secondary butoxide and zirconium Iso propoxide) using the solgel process. The parameters affecting the synthesis—solvent, concentration of precursor, R/H ratio (i.e., dilution of water in solvent)—were varied as also the temperature and pH. BET and TEM were used to measure nanosize. Diffuse reflectance spectroscopy and also qualitative optical absorption led to identical particle size estimate. The variation of process parameters was used to study the effect and interdependence of process parameters. Artificial Neural Networks was used to rigorously analyze the process. Although this led to confirmation of interdependence of parameters, the presence of a single overwhelming solvent variable was also established. Then the optimal process was used to synthesize more nanopowder. To produce bulk nanocomposite the nanopowders were sintered by varying the temperature and time period. The sintered lithoids were probed with a vickers hardness tester to measure elastic modulus, hardness, and fracture toughness. The results showed high elastic modulus, modest hardness, and very high fracture toughness.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.