热变形对316LN奥氏体不锈钢微观组织和力学性能的影响

利用Gleeble-1500热模拟试验机、光学显微镜、显微硬度计和纳米力学探针仪研究了温度、变形量和变形道次对316LN不锈钢组织和性能的影响。结果表明,试样3个变形区域的组织和显微硬度差距很大,难变形区变化最小,心部区域变化最大。统计分析不同试样的心部区域可知,大的变形量能得到细的晶粒和较高的显微硬度;高的变形温度能使材料充分再结晶;多道次变形后,试样的晶粒均匀性和圆整性得到改善;变形量为0.6时,1000℃下大变形后材料的纳米硬度和弹性模量高于原始材料,1200℃下则相反。     

45#钢高速冲击穿孔的显微组织

借助烧结的W合金圆柱体垂直冲击60mm厚的45^#热轧钢板实验,利用扫描电镜和光学金相显微镜研究了45^#钢高速冲击穿孔的显微组织。冲击波使穿孔周围的晶粒破碎,冲击引起的材料变形功转变为热能,以及侵彻过程中的摩擦作用,使穿孔表面熔化,靠近熔化区的晶粒发生再结晶。从穿孔表面到钢板内部可分为：熔化快凝层、再结晶细晶层、变形细晶层、形变层和正常基体组织。在细晶层和形变层中,铁素体晶粒的变形量要远远大于珠光体,部分珠光体开裂,其周围形成微裂纹和微孔洞。钢中的硫化锰夹杂在变形中被剧烈拉长。由于铁素体的塑性,钢板的破坏方式为延性扩孔。     

高强IF钢板沿厚度方向的织构和显微组织

利用X射线三维取向分布函数(ODF)方法和金相方法分别对加磷强化的高强IF钢沿厚度方向织构和显微组织的不均匀性及其变化规律进行了研究。结果表明:该高强IF钢板厚度中心层的γ纤维织构强度及体积分数最高,其次为1/4厚度层,最弱为表层;钢板的显微组织则由表层大小不均匀的晶粒逐渐转变为中心层大小非常均匀的等轴晶粒;这种织构和显微组织沿厚度方向的不均匀现象是由于在轧制过程中钢板的变形不均匀性所造成的。     

20CrMnTi钢两相区变形力学行为及微观组织研究

为了研究20CrMnTi钢温变形机理,利用等温压缩实验对该材料在两相区变形时温度与变形抗力之间的关系进行了研究,并用冶金学的方法对其进行了分析.结果表明:在Ac1温度以下变形时,铁素体的动态回复和珠光体中Fe3C相的球化导致流变应力在较小应变时出现"峰值",而后流变应力连续下降;在Ac1温度以上变形,770℃时因形变诱导铁素体相变,使流变应力下降,800℃时两相内的铁素体动态回复、奥氏体动态再结晶,使应变达到一定值后软化和硬化处于动态平衡,流变应力趋于稳定,且诱导相变和动态再结晶使晶粒超细化.     

变形温度对TA15合金组织和性能的影响

研究了变形温度对原始坯料为片状组织的TA15合金显微组织和性能的影响.随着变形温度(1030～930℃)的降低,合金的室温抗拉强度、延伸率及断面收缩率均增加.β区变形的镦粗试样为片状组织,在剧烈变形区和自由变形区,1080℃变形时β晶粒的动态再结晶程度比1030℃高.两相区变形镦粗试样的显微组织为过渡型组织,难变形区和剧烈变形区及自由变形区组织差别较大.     

大截面特钢锻材27SiMn组织细晶化与均匀化控制

利用Gleeble 1500热模拟试验机研究了热变形参数对27SiMn显微组织的影响及其机理,在此基础上改进了锻造工艺并进行了工业锻造实验,利用常规金相检验和电子背散射衍射技术(Electron backscattered diffraction,EBSD)对锻材27SiMn内部组织进行了剖析,分析了锻材心部粗大珠光体内部晶体学界面特征。结果表明,变形温度和变形量对27SiMn显微组织有重要影响,其机理在于热变形改变了奥氏体晶粒尺寸和内部界面特征,从而影响了铁素体形核位置和形核率,采用新锻造工艺将锻材心部珠光体组织平均尺寸由约100μm减小至约60μm,消除了"网状铁素体+粗大珠光体"的不均匀组织,获得了"块状铁素体+细小珠光体"的高均匀组织。     

基于动态大压下的510MPa级超细晶粒钢的组织及性能

基于动态大压下方法在1450热连轧机上生产出了510MPa强度级别超细晶粒热轧钢板。结果表明,通过基于动态大压下的热轧工艺,可以使Q235碳素钢的铁素体晶粒细化到4~6μm,可获得屈服强度为400MPa以上、抗拉强度510MPa以上强度级别的超细晶粒热轧钢板。超细晶粒热轧钢板的显微组织为铁素体和珠光体,铁素体晶粒多为细小均匀的等轴铁素体,铁素体晶粒内部及晶界位错密度较高,珠光体中的渗碳体大多以短棒状或颗粒状渗碳体存在。与用常规热轧工艺生产的Q235热轧钢板相比,基于动态大压下工艺生产的超细晶粒热轧钢板具有较高的强度和良好的韧性。     

喷射成形超高碳钢超塑性变形后的微观组织

研究了喷射成形超高碳钢的超塑性及其变形前后的显微组织.变形前,喷射态超高碳钢的组织为典型珠光体组织,而变形后,珠光体中的条状碳化物逐渐发生碎化和球化,并弥散分布于晶界处,此外,在铁素体基体中以及碳化物颗粒周围出现了高密度位错亚结构,而基体铁素体晶粒也有所伸长.喷射成形超高碳钢超塑性微观机制是以晶界滑动为主,晶内变形以及位错蠕变起了协调作用.     

TA19/TB2异质钛合金线性摩擦焊试验研究

目的 探究TA+TB钛合金组合的线性摩擦焊（LFW）接头组织及力学性能特点。方法 进行了TA19/TB2异质接头LFW焊接试验。利用光学显微镜及扫描电镜观察分析了接头微观组织特征,利用拉伸试验机及显微硬度计测试分析了接头力学性能。结果 TA19侧焊缝区为动态再结晶形成的等轴细晶组织,晶内析出了针状α''及细小片层α,热力影响区晶粒发生了不同程度的变形,在近焊缝较宽范围内形成水平流线形貌;接头中部界面TA19侧形成了直径约为2~3 μm的细小等轴晶;TB2侧焊缝区由动态再结晶形成的等轴晶及部分变形晶粒组成,热力影响区晶粒变形程度较低未形成流线形貌。接头界面两侧组织特征具有不同程度的强化效果,TA19侧从母材区到界面显微硬度值逐渐增大,TB2侧焊缝及热力影响区显微硬度值略高于母材;接头拉伸强度与TB2母材相当。结论 说明TA19与TB2钛合金可通过LFW获得可靠连接。     

SWRCH15A冷镦钢形变特征与组织结构研究

对湘潭钢铁有限公司生产的低碳冷镦钢SWRCH15A进行了1/3冷镦实验,利用光学显微镜、扫描电子显微镜、X射线衍射分析和透射电子显微镜分别对冷镦前后试样的横向、纵向截面进行了形变特征与微观组织的研究.结果表明,试样经1/3冷镦变形后呈鼓形,金相与扫描电镜观察发现组织呈明显的3个不均匀变形区域.冷镦变形后铁素体形成尺寸较小的纤维状亚晶结构,呈现〈111〉纤维织构和弱的〈100〉纤维织构.冷镦变形后,珠光体片层组织减少,片层厚度明显缩小.冷镦变形后组织中发现有一种新相形成.     

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.