热轧钛微合金化TRIP钢的组织与性能研究

对钛微合金化TRIP钢进行连续冷却转变曲线的测定,分析轧制与冷却工艺对其组织与性能的影响。结果表明:实验钢的奥氏体/铁素体、奥氏体/马氏体相变点分别在500~650℃和450℃左右;组织由铁素体/贝氏体及少量残余奥氏体组成;随着终轧温度的升高,实验钢的屈服强度和抗拉强度有所降低;随着空冷结束温度的降低,实验钢的屈服强度降低;当终轧温度和空冷结束温度分别为796℃和722℃时,实验钢的屈服强度,抗拉强度和强塑积分别为661,888MPa和25042MPa·%,其对应组织为细小的铁素体及板条贝氏体,铁素体基体上存在大量细小的析出物。     

利用TMCP开发F550高强度船板钢的实验研究

使用Gleeble 3800热模拟实验机研究了一种低C微合金SiMnCrNiMo钢的奥氏体连续冷却相变(CCT)行为,使用辊径750mm的二辊可逆实验轧机进行了系列TMCP实验,开发出F550高强度船板。生产F550船板的TMCP工艺为:在奥氏体再结晶区和未再结晶区进行两阶段轧制,精轧温度800～820℃,精轧压下率67%,轧后以14～18℃/s的速率冷却至350～500℃。钢板的显微组织为细密贝氏体,其屈服强度大于590MPa,抗拉强度大于700MPa,-60℃下Charpy冲击吸收能量高于230J。     

控制轧制中铁素体晶粒的细化及晶粒尺寸的予测

本文研究了控制轧制工艺参数对含铌与不含铌低碳钢的铁素体晶粒细化的影响规律。试验结果表明,热轧后铁素体晶粒尺寸d_f不受形变速度的影响(当ε为7～76秒~(-1)时),而形变量ε、形变温度T_d、轧前的奥氏体晶粒尺寸d_a、轧后冷速及钢的成分对d_f有重要影响。在单道次轧制中,所试验钢种的铁素体晶粒直径与各工艺参数的综合定量关系,可用下式表达。d_f=[55th((d_α-90)/25)+α]·ε~(-1)+b(T_d-750)~(1/2)+cd_α式中常数项a、b、c与钢的成分,冷却速度有关。试验表明,该式所表达的规律对其他低碳钢也适用。文中通过分析在细化晶粒方面,多道次轧制与单道次轧制的关系,将d_α推广为“等效奥氏体晶粒尺寸”,则该关系式可应用于多道次轧制,成功地予测了多道次轧制后铁索体晶粒尺寸。     

800MPa级冷轧耐候双相钢连续冷却相变及组织性能研究

为了探索一种800 MPa级冷轧耐候双相钢的连续冷却转变规律及退火后组织性能变化,利用For-master-FⅡ全自动相变仪及连续退火模拟实验机,进行了连续冷却转变(CCT)曲线的测定及连续退火实验.结果表明:实验钢的过冷奥氏体在很低的冷却速度(0.5℃/s)下即可发生马氏体转变,而珠光体转变较少.当冷速为80℃/s时,仅发生马氏体转变;退火后实验钢显微组织中的马氏体呈带状分布,经最优工艺退火后实验钢的显微组织为多边形铁素体(79%)+块状马氏体(16%)+细小的残余奥氏体(5%),残余奥氏体主要分布于马氏体晶粒内部或铁素体的晶界处;实验钢屈服强度为387 MPa,抗拉强度为863 MPa,延伸率为18%,强塑积达到15534.     

控轧控冷对低碳Mn-Nb-Cu钢拉伸力学性能的影响

研究了不同终轧温度及轧后冷却速度对低碳Mn-Nb-Cu钢的力学性能(σs，σb和δ5)的影响。研究结果表明，对控轧低碳Mn-Nb-Cu钢的力学性能的影响主要决定于钢的碳当量；随轧后冷却速度的提高，σs和σb提高，δ5降低；在奥氏体未再结晶区进行轧制，终轧温度对铁素体晶粒尺寸的影响较小。     

Q460C钢的连续冷却转变曲线

研究了Q460C钢连续冷却过程中奥氏体转变过程以及转变产物的组织变化,为制定生产工艺提供参考依据。由Q460C钢的连续冷却转变曲线(CCT图)和不同冷却速率的显微组织可知,当冷却速率较低时,形成粗大的块状铁素体和珠光体;当冷却速率大于3℃/s时出现贝氏体,形态似针状铁素体,其形成温度在450~600℃;当冷却速率大于15℃/s时,发生马氏体转变,马氏体的转变点约为350℃。     

高强度抗CO2腐蚀管线钢实验研究

在一定的轧制制度和轧后控冷速率下,通过添加适量的Cr能提高管线钢的抗CO2腐蚀能力,本工作重点研究了合金成分和轧制工艺参数对管线钢力学性能和耐腐蚀性的影响。结果表明:加入0.55%(质量分数)Cr,适当加大奥氏体未结晶区轧制时钢坯的累积变形量,并以23℃/s的冷却速率层流水冷,可得到屈服强度530MPa以上,抗CO2腐蚀性能较好的管线钢。     

控制轧制和控制冷却对低碳钢板的组织和抗冷脆性的影响

本文研究了控制轧制工艺参数(奥氏体化温度、道次压下率及终轧温度)对低碳钢板轧后铁素体晶粒平均直径和脆性转化温度的影响及其相互关系。试验结果表明:轧制工艺参数中终轧温度起主要作用,决定着轧后铁素体晶粒平均直径、脆性转化温度及-40℃时的冲击韧性;在约800℃终轧,效果最好。轧后快冷时间及冷却速度对低碳钢板的组织和脆性转化温度影响的试验结果表明,延长快冷时间及加快冷却对轧后组织产生复杂影响:使魏氏组织级别增大;使伪共析珠光体量增加;使珠光体退化及细化。这样复杂的组织变化,对脆性转化温度带来复杂的影响。文中提出了低碳钢中珠光体退化的几种机制。     

终轧温度对2205/Q235B双相不锈钢复合板组织和性能的影响

本工作以2205双相不锈钢和Q235B低碳钢为研究对象,采用Gleeble3800热模拟实验机将其压缩为复合板,并通过光学显微镜(OM)、扫描电镜(SEM)、力学及电化学性能测试仪器研究了终轧温度对2205/Q235B双相不锈钢复合板显微组织、剪切强度和耐腐蚀性能的影响规律。结果表明,在压下率一定的条件下,终轧温度在850～970℃范围内,2205和Q235B均能得到良好的结合界面,靠近复合界面的2205侧形成了一个奥氏体长条带,Q235B侧形成了宽度39.1～47.4μm的脱碳区域。随着终轧温度的降低,2205/Q235B双相不锈钢复合钢板的剪切强度显著提高,终轧温度为850℃时剪切强度最高,达到445 MPa。随着终轧温度的升高,2205双相不锈钢中δ铁素体含量逐渐增加,970℃时,δ铁素体含量达到最大值45.3%,2205不锈钢表面的耐腐蚀性能最佳。但随着终轧温度的升高,2205/Q235B结合界面处碳钢侧腐蚀深坑宽度由35.56μm增大到49.44μm,应注意腐蚀防护。     

Q345钢奥氏体连续冷却转变曲线(CCT图)

研究了Q345钢连续冷却过程中奥氏体转变过程及转变产物的组织和性能,为制定生产工艺提供参考依据.利用膨胀法结合金相-硬度法,得到不同冷却速度连续冷却时的膨胀曲线和相应的金相组织及硬度,用DTA法及膨胀法测定其临界点Ac1、Ac3以及Ms,获得了Q345钢的连续冷却转变曲线(CCT图).由CCT图和不同冷却速度的显微组织照片可知,当冷却速度比较低时,形成较粗大的块状铁素体和珠光体,当冷却速度大于0.5℃/s时出现贝氏体,形态似针状铁素体,其形成温度在450~600℃左右,当冷却速度大于20℃/s时,发生马氏体转变,马氏体转变点约为400℃.     

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.     

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.     

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...     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

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.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from