可锻铸铁孕育剂近展

可锻铸铁是一种具有团絮状退火碳的韧性铸铁。为了缩短可锻铸铁退火周期,提高可锻铸铁机械性能,国内外开展了许多研究工作。其中孕育处理是一种简便有效的方法。本文综述了可锻铸铁孕育技术研究近况,并提及了一些其它有效的方法。一、可锻铸铁石墨化孕育剂在可锻铸铁生产中,可锻化退火是一个薄弱环节。为此,各国竞相进行研究,寻求确有实效的促进固态石墨化的孕育剂。硅铁是灰铸铁、球铁中常用的孕育     

可锻铸铁低温退火

可锻铸铁采用锌气氛退火新工艺后,退火周期虽然缩短到40h以内,但能源消耗仍然是很大的。我厂在此基础上又开始采用DH-1型可锻铸铁专用催化剂进行催化低温退火新工艺。该工艺是在国家规定的可锻铸铁的化学成分不变,不经孕育处理的条件下,靠DH-1催化剂自身强烈的石墨化作用,促使退火件石墨化核心迅速生成,继而当退火件达到700℃时,催化剂分解生成物对铸件起强     

复合孕育对可锻铸铁组织和性能的影响

本文试验研究了以稀土、钡为主的几种复合孕育剂对可锻铸铁的孕育效果。硅钡铁、稀土硅钡铁均能大大缩短可锻铸铁第一,第二阶段石墨化时间,它们都是较理想的可锻铸铁孕育剂。硅钡铁,稀土硅钡铁能使可能锻铸铁铸态组织细化,退火温度降低,退火时间缩短,机械性能提高。     

铜对可锻铸铁组织和性能的影响

本文研究了Ｃｕ－Ｂｉ复合孕育对可锻铸铁可石墨化和机械性能的影响。与单独加Ｂｉ孕育相比，复合孕育剂中含０．２％Ｃｕ时，可明显缩短第一和第二阶段石墨化时间，经Ｃｕ－Ｂｉ复合孕育后，机械性能超过ＫＴＨ３５０－１０。     

球化孕育处理工艺对下贝氏体铸铁组织特性及力学性能的影响

采用真空中频感应炉,通过改变球化孕育处理工艺获得具有不同形态石墨的铸造试样,将铸件加热到860 ℃保温2 h,使用20 ℃的硝酸钠、亚硝酸钠饱和溶液将其连续冷却至室温,并在250 ℃低温回火2 h后空冷,获得具有不同形态石墨的下贝氏体基体组织。研究了球化孕育处理工艺对石墨球化效果的影响,以及石墨形态对热处理显微组织和力学性能的影响。结果表明：球化处理温度及时间对铸铁中的镁吸收率有显著影响,超过1 500 ℃时,镁烧损加剧,当球化处理温度为1 450 ℃,镁吸收率达到64.2%;孕育剂添加工艺也是影响铸铁中石墨的形态和分布的重要因素,当一次孕育和二次孕育添加量分别为0.8%和1.2%时,石墨的形态以球状为主,尺寸细小且分布均匀,石墨的球化率为93%,球化级别达到2级,尺寸级别为9级;另外,均匀分布的球状石墨有利于提高热处理后下贝氏体铸铁的综合力学性能。     

加锑可锻铸铁孕育剂的研究

在可锻铸铁孕育处理剂中应用锑和铝的孕育作用，配以适当的铅，研制成功了Ｐｂ－Ｓｂ－Ａ１型孕育剂。通过大量试验证明：在常规可段铸铁化学成份范围内，ＰｂＳｂ－Ａ１型孕育剂孕育效果稳定，能够保证中等壁厚的可锻铸铁件获得全白口组织，对固态石墨化过程没有不利影响，可使主要机械性能指标略有提高；一般情况下可替代现生产中使用的较昂贵的铀孕育剂。     

稀土在可锻铸铁复合孕育处理中作用

本文通过多次试验,分析了稀土在复合孕育处理铁索体黑心可锻铸铁时, 对石墨化过程及其组织和性能的影响。试验表明,加入适量稀土可大大增加石墨核心,细化石墨颗粒,加速石墨化过程。缩短遇火周期,从而节省燃料,降低能耗。处理后的性能与GB978-67比较,在塑性相近下,可提高强度39.2～58.8N/mm~2以上。     

加锑可锻铸铁孕育剂的研究

在可锻铸铁孕育处理剂中应用锑和铝的孕育作用，配以适当的铅，研制成功了Ｐｂ－Ｓｂ－Ａｌ型孕育剂。通过大量试验证明：在常规可段铸铁化学成份范围内，ＰｓＳｂ－Ａｌ型孕育剂孕育效果稳定，能够保证中等壁厚的可锻铸铁件获得全白口组织，对固态石墨化过程没有不利影响，可使主要机械性能指标略有提高；一般情况下可替代现生产中使用的较昂贵的铋孕育剂。     

铁素体可锻铸铁锌气氛退火工艺

可锻铸铁退火周期长,燃料消耗大,退火质量不稳定是当前生产中急待解决的问题。近两年,石家庄市机械研究所、河北机电学院、河北工学院等单位组成锌气氛退火试验研究小组,并先后在石家庄市农机厂,河北三七四厂进行生产试验,将铁素体可锻铸铁退火的高温石墨化时间缩短到1～3小时,低温石墨化时间缩短到5～7小时,总退火周期:0.5吨燃煤室状炉为13～15小时,2吨燃煤室状炉为17～20小时;10～15吨燃煤室状炉为     

稀土镁球墨铸铁线路金具

我国的高压架空电力线路金具,过去一直采用可锻铸铁件。可锻铸铁件在生产过程中需经较长时的高温(910～950℃)和低温(700～750℃)两个阶段的石墨化退火,生产周期长,劳动强度大。为了解决上述问题,我厂采用本省的钒钛生铁生产稀土-镁钒钛球墨铸铁金具。铸态抗拉强度为60～66.5公斤/毫米~2,延伸率为2.4～3.6％;经760～800℃退火4小时后,     

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.     

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....     

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。     

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.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion.