核反应堆蒸汽发生器压力边界焊接接头的显微组织及硬度

根据核反应堆蒸汽发生器压力边界水室分隔板与定位板之间的结构特点,采用不对称X形坡口形式对Inconel600合金进行对接焊,研究了焊接接头的显微组织与硬度。结果表明:与母材相比,焊接接头热影响区的晶粒变大,熔合区组织过渡良好;焊缝边缘为垂直于熔合线向焊缝中心生长的柱状晶,焊缝中心为柱状晶和等轴晶的混合组织;在正面焊缝和反面焊缝之间的重熔区形成了较多的等轴晶;焊缝区物相组成与母材的相似,均由基体γ相、γ′间隙相及碳化物组成;焊缝重熔区的硬度最高,热影响区的硬度最低。     

铝合金搅拌摩擦焊技术研究

论述了搅拌摩擦焊的焊接方法、工艺过程和基本原理；通过大量的工艺参数优化，解决了焊缝中的孔洞问题，使ＬＦ６板材搅拌摩擦焊的焊缝达到与母材等强，ＬＹ１２焊后未经热处理，连接强度接近母材的８０（。由金相分析可以看出，搅拌摩擦焊属于固相连接，焊缝晶粒细小，无气孔、夹杂、裂纹等焊接缺陷。初步应力测试发现，搅拌摩擦焊焊缝比熔焊焊缝的残余应力低。试验研究结果表明，搅拌摩擦焊焊接过程稳定可靠，焊接接头性能良好，具有广泛的应用前景。     

铝对渗铝钢焊缝金属组织与性能的影响

本文通过X 射线衍射、透射电镜(TEM)、扫描电镜(SEM)和电子探针(EPMA)等测试技术分析和讨论了铅对GL 渗铝钢管焊接时Cr-Ni 奥氏体焊缝金属组织和性能的影响。结果表明:GL 渗铝钢的渗铝层主要由FeAl、Fe_3Al 和(α-Fe(Al)固溶体组成,晶粒细小,可焊性好。此外,在渗铝钢焊接过程中,熔入焊缝的铝使Cr-Ni 奥氏体焊缝金属中的δ铁素体的数量和形态发生了变化,但在δ铁素体中并不富铝,铝元素在δ相和γ相中的分布是随机的。     

高温长期时效对镍基单晶高温合金γ′相形貌的影响

研究了长期时效对一种镍基单晶高温合金γ′相形貌的影响。结果表明:合金在950℃时效100h后,γ′相正方度略有下降,500h后γ′相开始沿不同的[100]方向长大。合金在1050℃时效100h后,γ′相开始沿不同的[100]方向长大,长大速度明显高于950℃时效。γ/γ′相界面能和弹性应变能的降低是γ′相长大的驱动力,γ′相按Ostwald熟化方式长大,即大的γ′相长大,小的γ′相溶解,高温长期时效过程中无有害相析出,表明合金的组织是稳定的。     

轨道车辆铝合金地板搅拌摩擦焊残余状态分析

搅拌摩擦焊作为一种先进的固相焊接技术,以其针对铝合金材料焊接效率高、焊后缺陷小、环境污染小等优点被逐渐地广泛应用。但是目前缺乏搅拌摩擦焊焊接中力学过程的研究,也鲜有力学过程对于焊缝残余状态影响的资料,不利于搅拌摩擦焊的推广应用。因此,本文以某型地铁车辆铝合金地板的焊接为研究对象,对搅拌摩擦焊工作原理及焊缝残余状态规律进行了分析,总结了摩擦焊接过程中的力学规律与导致焊缝残余应力不对称分布的原因。     

固溶温度对LF9镍基合金中η和γ′相尺寸、数量及冲击性能的影响

用SEM、TEM、EDS和ICP-AES等方法进行微观组织分析,用冲击试验机测定冲击性能,研究了LF9镍基合金经(800～1 040)℃×1 h固溶水冷处理后γ′相和η相的变化及对合金冲击性能的影响.结果表明:合金中的γ′相在高温下发生长大,原始锻态γ′相的平均尺寸约20 nm,980℃固溶时平均尺寸约120 nm,而1 020℃时γ′相完全溶解;820℃时次生析出η相沿晶界平行往外生长,在η相两侧形成贫γ′区,约980℃时析出量达到最多,约1 040℃时完全溶解;贫γ′区的微塑性区能减缓裂纹的扩展速率,改善合金的冲击性能;η相的析出数量增多和尺寸增大降低了合金的冲击性能.     

焊前和焊后调质处理下25Cr2Ni4MoV钢焊接接头的组织及性能

对比研究了焊前和焊后调质处理条件下25Cr2Ni4MoV钢焊接接头的显微组织、力学性能和耐腐蚀性能,调质处理工艺为920℃×1 h油淬+580℃×2 h回火,焊接工艺为手工焊条电弧焊.结果表明:焊前调质处理的接头焊缝组织为板条马氏体+δ-铁素体+M23C6碳化物,焊后调质处理使焊缝中的δ-铁素体溶解,形成了板条马氏体+...     

大厚度TA15钛合金板潜弧焊接头的组织及拉伸性能

在添加TA1纯钛中间层填充板的条件下,对64mm厚TA15钛合金板进行潜弧焊接,分析了焊接接头的显微组织、拉伸性能以及焊缝中氢、氧、氮的含量,并与不添加中间层的普通潜弧焊接头的拉伸性能进行了对比。结果表明:添加中间层后焊接接头的焊缝区组织为较大尺寸的柱状晶,晶内分布着不同方向的针状α′相,母材区组织为初生α相和少量β相,热影响区组织中既存在α相,也存在α′相;添加中间层后焊接接头的抗拉强度比普通潜弧焊接头的有所降低,但其塑性显著提高,焊缝中氢、氧、氮的含量比母材中的有所降低。     

热处理对激光增材In718/316L功能梯度材料组织和性能的影响

研究1 080 ℃ (HT1)和980 ℃ (HT2)固溶温度的固溶双时效处理对激光定向能量沉积(Laser directed energy deposition, LDED)的In718/316L功能梯度材料(Functionally gradient material, FGM)微观组织的影响，以揭示热处理诱导的微观组织演变对In718/316L FGM硬度和拉伸性能的影响机理。结果表明，随着In718粉末含量的增加，In718/316L FGM的微观组织沿增材方向呈现由等轴晶向柱状晶的转化，固溶双时效热处理后，In718/316L FGM中的铁素体含量降低，同时在靠近In718的区域析出大量的γ′、γ″和δ强化相。HT2试样的晶粒比HT1试样的更细。随着In718粉末含量的增加，In718/316L FGM的硬度呈现出先减后增的趋势，热处理后，随着γ′和γ″等强化相的析出，In718/316L FGM的整体显微硬度、抗拉强度和塑性得到显著提高。热处理前后试样都以韧性断裂为主，但热处理后韧性特征更为显著。相比之下，HT2热处理后In718/316L FGM的强塑性配比更佳。     

12Cr2Mo1R钢焊条电弧焊焊接接头的性能

采用焊条电弧焊工艺用奥氏体A302焊条对12Cr2Mo1R钢进行焊接,焊后对焊接接头进行425℃保温370h的热处理;对焊接接头进行了显微组织观察、能谱分析、物相测定和高温拉伸、冲击试验。结果表明:焊缝区组织为奥氏体、δ铁素体和少量碳化物;焊接接头高温拉伸屈服强度比母材的大,焊缝区的冲击功比母材的低;在焊缝区产生了少量脆性碳化物(M23C6型)和铁-铬新相,造成焊缝区的脆性比母材的增大。     

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.