大线能量低焊接裂纹敏感性钢的焊接(一)——热影响区强韧性机理研究

利用焊接热模拟技术对一种610MPa级大线能量低焊接裂纹敏感性钢的热影响区(HAZ)强韧化机理进行了研究.结果表明:在大线能量焊接条件下,该钢HAZ的强韧性决定于HAZ组织中针状铁素体的含量和形态,其含量越高、越细小,对HAZ的强韧性越有利;钢中TiN粒子的存在可促进HAZ针状铁素体的形核,且当钢中Ti/N比值接近理想化学配比3.42时,可明显细化针状铁素体,提高HAZ韧性.     

大线能量低焊接裂纹敏感钢的焊接（一）——热影响区强韧性机理研究

利用焊接热模拟技术对一种610MPa级大线能量低焊接裂纹敏感性钢的热影响区（HAZ）强韧化机理进行了研究。结果表明：在大线能量焊接条件下，该钢HAZ的强韧性决定了HAZ组织中针状铁素体的含量和形态，其含量越高，越细小，对HAZ的强韧性越有利；钢中TiN粒子的存在可促进HAZ针状铁素体的形核，且当钢中Ti/N比值接近理想化学配比3.42时，可明显细化针状铁素体，提高HAZ韧性。     

高强钢焊材及焊接性的国内外研究进展

对高强钢焊接问题进行分析介绍，主要阐述了高强钢焊接材料的发展现状，线能量、氢、氮、氧对高强钢焊缝金属性能的影响。介绍了高强钢大线能量焊接时，第2相粒子在热影响区粗晶粒区（CGHAZ）诱发生成细晶针状铁素体，从而使焊缝金属具有高强度高韧性。     

大线能量低焊接裂纹敏感性钢的焊接(二)--热影响区组织及晶内铁素体形核机理研究

利用焊接热模拟技术和透射电子显微镜对大线能量氏焊接裂纹敏感性钢的焊接热影响区（HAZ）组织及晶内铁素体（IGF）的形核机理进行了试验研究。通过对大线能量焊接（100kJ/cm)条件下HAZ中IGF精细组织分析，认为IGF非均匀形核核心主要为富含MnS和Si元素的Ti2O3复合粒子。     

Ti-Zr微合金化高强钢焊接热影响区性能及组织特征

研究了Ti-Zr微合金化高强钢100 kJ/cm大线能量焊接热模拟和192 kJ/cm大线能量电渣焊热影响区(HAZ)的力学性能和组织特征。研究表明:不同线能量下,HAZ均具有良好的强韧性;HAZ组织以针状铁素体为主,电渣焊HAZ组织相对粗大,并出现少量均匀分布的M-A岛;不同线能量下第二相夹杂物均为含Ti,Zr及Mn的复合氧化物,热模拟HAZ组织中夹杂物尺寸较小,且数量较多,对晶内针状铁素体形核促进作用更大。     

稀土对700 MPa级大焊接热输入用钢的组织和性能影响

面向700 MPa级大焊接热输入用钢的迫切需求,通过加稀土(RE)改进制备钢板,基于Gleeble试验模拟焊接热影响区,并开展力学性能测试,以及显微组织和断口分析,结果显示,钢板具有优良的强韧性匹配和抗大焊接热输入性能,母材屈服强度R_(eL)≥600 MPa,抗拉强度R_m≥700~850 MPa,断后伸长率A≥16%,-40℃下冲击吸收能量KV_2≥47 J、焊接热影响区的冲击吸收能量KV2≥34 J,满足相关技术要求。分析发现,添加RE可明显改善钢板母材和焊接热影响区的低温韧性,主要由于细小含RE复合氧化物作为针状铁素体的形核核心,促使焊接热影响区内形成针状铁素体,明显改善了焊接热影响区的韧性。     

汽车大梁用BS700MC低碳微合金钢焊接接头的组织和力学性能

通过裂纹敏感性、显微硬度、弯曲、冲击、拉伸试验及组织观察,研究了汽车大梁用BS700MC低碳微合金钢焊接接头的显微组织和力学性能。结果表明:采用WH80-G焊丝焊接时,BS700MC钢具有较好的抗裂性,焊前不需要预热处理;焊接接头的焊缝组织为针状铁素体和极少量贝氏体与先共析铁素体;焊接接头具有良好的综合力学性能,焊缝硬度为380HV,与母材相当,接头底部硬度分布波动明显,热影响区存在软化现象,在-20~20℃范围内焊接接头具有良好的冲击韧性;接头的抗拉强度为815 MPa,为母材的97.1%,断裂于热影响区,拉伸断口为韧窝与解理台阶混合型断口。     

NM450耐磨钢板焊接接头的显微组织和力学性能

采用ER50-6焊丝对NM450耐磨钢板进行了CO_2气体保护焊,研究了接头的显微组织、力学性能,以及焊接冷裂纹敏感性。结果表明:焊缝组织为块状铁素体+针状铁素体,热影响区粗晶区和正火区的组织分别为板条马氏体和铁素体+渗碳体;焊缝区、粗晶区、正火区和不完全重结晶区的硬度分别为220,412,234,386HV,马氏体分解导致正火区和不完全重结晶区硬度降低;接头的抗拉强度为768 MPa,焊缝中心、影响区和母材的-20℃夏比冲击吸收功分别为110,140,88J;此钢有一定的冷裂纹敏感性,在环境温度32.6℃、不预热焊接时不会产生裂纹,在环境温度-1.4℃、不预热焊接时,接头根部裂纹率和截面裂纹率均为100%,80℃预热焊接则不会产生焊接裂纹。     

原油储罐用钢的开发与应用最新进展

介绍了中国原油储罐用大线能量用钢的开发和应用现状，并介绍了鞍钢新轧钢股份有限公司和上海宝钢集团公司最近开发的低焊接裂纹敏感性大线能量用钢。     

t_(8/5)对高强度余热处理棒材焊接热影响区组织和力学性能的影响

采用Gleeble-3500型热模拟试验机研究了不同t8/5对高强度余热处理棒材焊接热影响区(HAZ)显微组织和力学性能的影响。结果表明:随着t8/5增大,粗晶热影响区(CGHAZ)的组织由羽毛状上贝氏体、短条状下贝氏体和铁素体转变为粒状贝氏体、珠光体和铁素体;HAZ的室温冲击功先增大后减小,并在t8/5=100s时达到最大;当t8/560s后,CGHAZ组织由珠光体和铁素体组成;HAZ的硬度随着t8/5增大而降低;高强度余热处理棒材能够满足实际生产需要的t8/5区间为20~300s。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.