利用控轧控冷技术开发热轧不锈钢复合板的实验研究

使用Gleeble-3500热模拟试验机研究了Q345R的奥氏体连续冷却相变(CCT)行为,利用二辊可逆试验轧机进行了系列控制轧制控制冷却(TMCP)实验,开发出了不锈钢(316)/低碳钢(Q345R)复合板。较合理的工艺为:在奥氏体再结晶区进行轧制,终轧温度为1000~1050℃,总压下量为75%,轧后以0.2~7℃/s的速率冷却至450℃以下后空冷,随冷却速率的增加,Q345R钢板的显微组织从铁素体(F)+珠光体(P)向铁素体(F)+贝氏体(B)过渡,屈服强度范围330~430MPa,抗拉强度范围为535~595MPa,0℃的冲击吸收功高于50J;复合板界面结合强度大于350MPa,抗弯性能合格。     

变形制度对低碳锰钢组织性能的影响

为了获得细晶铁素体/贝氏体的复相组织,通过控轧控冷工艺研究了低碳锰钢在奥氏体区变形时变形量、终轧温度和卷取温度对组织演变和力学性能的影响规律.研究表明,增加变形量(对应道次间隔时间缩短)可以细化铁素体晶粒,但当终轧温度降低到800℃时,变形量的增加以及开冷温度的降低不利于贝氏体组织的获得.通过调整变形量、终轧温度、可开冷温度并适当降低卷取温度,可使实验钢获得晶粒尺寸约为5μm的铁素体和10%~20%的贝氏体组织,低碳锰钢强塑性能良好.     

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。     

轧制工艺对CSP生产低碳贝氏体高强钢组织和性能的影响

研究了CSP工艺生产低碳贝氏体高强钢的工艺控制与显微组织和力学性能的关系.通过比较不同终轧温度和卷取温度对低碳贝氏体高强钢组织性能的影响,得出钢板最终组织为不同比例的铁素体加贝氏体复相组织,且随着终轧温度和卷取温度尤其是卷取温度的降低,组织中贝氏体的体积分数增多,组织更加细小均匀,并且可以获得细小弥散的M-A组织和析出粒子,从而提高钢的屈服强度和韧性.     

终冷温度对高强度抗震钢筋组织和性能的影响

用Gleeble-3800热模拟机进行高强度抗震钢筋的热模拟实验,使用金相显微镜(OM)、场发射扫描电子显微镜(SEM)、高分辨透射电子显微镜(TEM)和万能拉伸试验机等手段表征其微观结构、第二相、力学性能和断口形貌,研究了终冷温度对高强度抗震钢筋的组织和性能的影响并揭示微合金元素细化晶粒的机理。结果表明：实验钢的显微组织主要为铁素体和珠光体,随着终冷温度的降低铁素体晶粒细化。终冷温度为650℃时实验钢中分布在铁素体基体上的主要析出相 (Nb, Ti, V)C和(V, Nb, Ti)C的平均粒径约为2 nm和5 nm。随着终冷温度的降低实验钢的抗拉强度和屈服强度都增加,终冷温度为650℃时其抗拉强度和屈服强度分别为638.75 MPa和467 MPa,强屈比为1.37。在不同终冷温度实验钢的拉伸断口主要为等轴韧窝,其尺寸和深度不同。     

Mo和Ni对高强无碳化物贝氏体钢组织转变与力学性能的影响

测定了不含Mo和Ni、含Ni和含Mo三种成分实验钢的CCT曲线,利用扫描电镜、透射电镜观察了连续冷却及轧后空冷条件下三种钢的显微组织变化,并对其力学性能进行了检测分析。结果表明:添加少量Mo和Ni能有效延迟高强无碳化物贝氏体钢CCT曲线中高温铁素体相变,降低Ms点,促进贝氏体相变。Mo和Ni的添加可使实验钢轧后空冷组织由铁素体+粒状贝氏体+M/A混合组织转变为无碳化物贝氏体组织(BF+AR),Ni对贝氏体板条的细化作用比Mo显著,但组织中会出现少量粗大贝氏体;Mo对轧后相变过程中粗大贝氏体的形成有一定抑制作用,可使获得的无碳化物贝氏体组织均匀性更好。Mo和Ni均可有效提高高强无碳化物贝氏体钢的力学性能,其中Ni对抗拉强度的提升作用强于Mo,而Mo则更有利于冲击韧性的提高。含Ni的2#实验钢抗拉强度比不加Ni和Mo的1#实验钢提高252MPa,含Mo的3#实验钢-20℃下冲击吸收功比1#提高11J。     

冷却工艺对货油舱用耐蚀钢组织性能的影响

基于货油舱用耐蚀钢的服役环境设计并冶炼了一种新型耐蚀钢,根据试验钢变形奥氏体连续转变曲线,采用控制轧制和控制冷却的技术将锻后110 mm坯料减薄至16 mm。热轧板材的年平均腐蚀速率分布在0.235~0.273 mm/a,小于船级社要求的1 mm/a。利用扫描电镜、透射电镜、拉伸试验机和冲击试验机进行了耐蚀钢的显微结构分析及力学性能研究,探究了控制冷却工艺对耐蚀钢组织性能的影响规律。结果表明:在终冷温度669 ℃、冷却速度8.9 ℃/s的条件下,耐蚀钢显微组织主要为铁素体、贝氏体和退化珠光体。降低终冷温度或提高冷却速率有利于抑制珠光体转变,促进针状铁素体和贝氏体相变进程,增加小角度晶界数量,提高耐蚀钢的组织均匀性和力学性能。当终冷温度降低至597 ℃,冷却速度增大到13.1 ℃/s,耐蚀钢组织为针状铁素体、粒状贝氏体和板条贝氏体混合结构,不均匀分布且粗大尺寸的板条结构弱化了材料的抗冲击性能。     

超快冷对厚规格X80管线钢组织性能的影响

采用Gleeble试验机研究了厚规格(22mm)X80管线钢的动态相变行为,得到了动态CCT曲线,对不同冷却工艺钢的显微组织、力学性能以及析出行为进行了系统的对比分析。结果表明,在40℃/s的高冷速条件下试验用钢的组织为细小的板条贝氏体(LB),相变终止温度达到约400℃;在超快冷工艺条件下钢卷的强度有所提高,韧性没有明显的变化;其显微组织中准多边形铁素体(QF)的比例下降,板条贝氏体(LB)的比例上升,M/A岛的比例有所降低;轧后快冷可抑制奥氏体中的析出,提高Nb在铁素体中的析出比例,使析出粒子尺寸更加细小,提高析出强化效果。     

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。     

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.     

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.     

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.     

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.     

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.……     

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.     

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.     

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.