马氏体钢中δ-铁素体的表征及影响

利用冲击试验机、维氏硬度计、金相显微镜、扫描电镜和能谱分析技术研究工业生产大型锻件马氏体耐热钢中的δ-铁素体含量以及δ-铁素体对冲击性能的影响。研究表明:δ-铁素体是一种富W、Mo、Cr和V且贫Mn相,接近水口端比冒口端含量高,它的存在是造成马氏体耐热钢冲击韧性低的主要原因。可通过控制铁素体形成元素到最低限和奥氏体形成元素到最高限,抑制δ-铁素体的析出,获得完全马氏体组织及良好的综合力学性能。     

电站管道用ASME P92钢材显微金相组织研究

通过对电站管道用ASME P92钢材进行了显微金相组织分析，结果显示在ASME P92钢中出现了回火马氏体＋δ-铁素体组织形态，其中δ-铁素体含量超过10%。分析表明在高温回火过程中实际温度和升温降温速率控制不当是产生δ-铁素体组织的主要原因。     

X12CrMoWVNbN10-1-1钢中δ铁素体的消除

X12CrMoWVNbN10-1-1钢在高温下加热和长时间保温时会析出大量δ铁素体,并对力学性能产生较大影响;将原始试样经高温预处理后,分别经1 000～1 100℃长时间保温和热镦粗后进行冲击性能测试,研究了热处理和热镦粗对试验钢中δ铁素体的影响。结果表明:热处理对δ铁素体的消除作用不明显,力学性能改善有限;热镦粗钢中的δ铁素体随着再结晶的发生而消除,残余δ铁素体与等效应变量成反比,且力学性能也提高显著。     

δ铁素体对316LN不锈钢冲击韧性的影响

针对核用316LN不锈钢锻件试环,采用OM,SEM,EDS等设备研究了δ铁素体对其冲击韧性的影响。结果表明,试环固溶处理的保温时间较短,导致锻件芯部δ铁素体组织无法全部分解而残留于奥氏体基体中;冲击过程中,在剪应力的作用下裂纹优先在δ铁素体与奥氏体界面开裂,发生脆性断裂,进而显著降低其冲击韧性。     

低合金高强度钢焊缝熔敷热处理冲击韧性下降原因分析

用于高参数压力容器的低合金高强度钢采用窄间隙埋弧焊,在焊后热处理后其焊缝冲击韧性大幅下降。利用扫描电镜和透射电镜,对焊缝熔敷金属焊后热处理前后的显微组织变化进行研究,找出其冲击韧性下降原因。结果表明：低合金高强度钢焊缝焊态时组织为针状铁素体,在晶内有细小碳化物弥散分布;经焊后热处理,针状铁素体变为块状,碳化物在晶界大量析出,导致晶界脆化和冲击韧性下降。     

模拟热成形后的热处理对08Ni3DR钢性能的影响

国产08Ni3DR钢为-100℃低温用钢,通过制定不同的热处理冷却方式,研究正火+回火后对母材组织和性能的影响。结果表明,经正火水冷+回火的热处理制度后,其强度及冲击韧性综合性能最佳,金相显微组织为贝氏体+少量铁素体,晶粒度达到9级。     

浅谈升降温速度对N-TUF490钢低温冲击性能的影响

通过对高强钢N—TUF490低温冲击韧性的试验，指出焊后消除应力热处理过程中升降温速度的缓慢，使500～580℃的停留时间增长，导致该材料低温冲击韧性下降。     

BHW-35钢焊缝熔敷金属热处理脆化机理研究

用于高参数锅炉的BHW－35钢采用窄间隙埋孤焊，在焊后热处理后其焊缝冲击韧性大幅下降。利用扫描电镜（SEM）和透射电镜（TEM），对焊缝熔敷金属焊后热处理后的显微组织变化进行研究，找出其冲击韧性下降原因。结果表明：BHW－35钢焊缝焊态时组织为针状铁素体，在晶内有细小碳化物弥散分布；经焊后热处理后，针状铁素体变为块状，碳化物在晶界大量折出，导致晶界脆化和冲击韧性下降。     

30CrMnSiA钢多相复合组织的低温冲击性能研究

通过热处理方法,在30CrMnSiA钢中,获得了马氏体十贝氏体十铁素体十未转变的奥氏体纤维状和半纤维状多相复合组织,以及纤维状和半纤维状马氏体十铁素体双相组织,对不同复相组织与传统调质组织的低温冲击性能进行了对比研究。借助扫描电镜和透射电镜,对断口形貌、组织形态进行了观察。结果表明:多相复合组织具有低的冷脆倾向,高的冲击韧性。并探讨了低温冲击性能变化的机理。     

低温用铁素体球墨铸铁的研制

球墨铸铁作为重要的金属结构材料已广泛应用于机械制造业。通过对低温用铁素体球墨铸铁化学成分的选择、球化和孕育工艺的控制，以及热处理方案制定原则的研究分析，确定了低温用铁素体球墨铸铁的合理生产方案，成功地研制出了低温用铁素体球墨铸铁。     

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...     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

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.     

交通荷载作用下桥梁结构参数识别方法

应用动力节点加载法,将作用在桥梁上的交通荷载转化为等效节点荷载,再用两步构造法识别结构物理参数.第1步,用Newmark-β方法变换结构运动方程,并用结构的加速度响应求得变换空间内的位移、速度和加速度响应;第2步,基于最小二乘原理,构造出变换空间内求解结构参数的递推式,进行结构物理参数识别.数值模拟结果表明,在交通荷载作用下,该方法能够快速、准确地进行桥梁结构参数识别.     

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.     

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...