共查询到20条相似文献,搜索用时 62 毫秒
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在-200 ℃~室温范围内,采用拉伸和夏比冲击试验测定了1Cr22Mn15N高氮奥氏体不锈钢的韧-脆转变温度(DBTT),并通过扫描电镜(SEM)、透射电镜(TEM)和X射线衍射(XRD)等方法对该钢在低温下的韧-脆转变现象进行了研究.结果表明:该钢发生韧-脆转变的温度在-110℃左右;最早出现脆性滑移平台的温度在-80℃,并有诱发的ε相出现;其断口形貌由韧窝→韧窝 准解理→解理脆断变化,断裂形式为穿晶断裂;可能是由于在脆性第二相上形成微裂纹,导致在两个滑移面之间产生穿晶脆性断裂. 相似文献
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《机械制造与自动化》2017,(5):45-47
高氮钢焊接技术是高氮钢应用的关键技术之一,采用熔化极惰性气体保护焊接(MIG)方法,选用自制高氮钢焊丝对16 mm厚高氮奥氏体不锈钢进行焊接,分析了焊接接头显微组织、硬度、力学性能。结果表明,氮气的加入能够影响焊缝的结晶行为,不同比例氮气保护气氛下的焊接接头,焊缝区硬度均低于母材,20%氮气的加入对改善焊缝区域显微硬度效果最为显著,高氮奥氏体不锈钢焊接接头抗拉强度随着氮气比例的变化呈现先增大后减小的趋势。 相似文献
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304不锈钢属于非稳态奥氏体不锈钢,在应变强化过程中,应变温度、应变速率、应变量等均可改变应变诱发马氏体的转变量和转变速率及内部组织滑移线、形变孪晶、位错和层错密度的转变量和转变速率,从而表现出不同的应变硬化行为。针对304奥氏体不锈钢,主要从应变速率敏感指数、应变硬化指数两方面,研究了应变速率对其室温应变硬化行为的影响。 相似文献
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SUS304亚稳奥氏体不锈钢在耦合摩擦和变形条件下的磨损行为研究 总被引:1,自引:0,他引:1
在自制的耦合摩擦和变形的试验机上初步研究了SUS304亚稳奥氏体不锈钢带的磨损变形行为,分析了在耦合摩擦和变形条件下的形变量、磨痕表面的马氏体转变以及磨痕形貌与试验条件的关系。结果表明:研制的试验机实现了SUS304亚稳奥氏体不锈钢带的摩擦和塑性变形的耦合行为;不仅带试样摩擦表面的形貌随正压力增加变化明显,而且其形变量和诱发转变的马氏体量均增大,但马氏体量增加对SUS304奥氏体不锈钢的磨损无明显影响。 相似文献
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ZGlCr17Mnl2Ni2N铬锰氮不锈钢是一种高铬、高锰、高氮、低镍型奥氏体不锈钢,金相组织为单一奥氏体,是耐腐蚀不锈钢,其力学性能很高。因其独特的物理特性,在发电行业中有着很特殊的用途。 相似文献
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利用小冲杆试验对304L不锈钢进行了应力腐蚀敏感性评估,研究了加载速度和腐蚀介质对评估结果的影响,并对小冲杆试样的断口形貌和显微组织进行了分析。结果表明:最适合304L不锈钢评估的小冲杆应力腐蚀试验介质为1.0mol.L-1 NaCl+0.5mol.L-1 HCl混合溶液,加载速度为3×10-3 mm.min-1;在以上介质中,304L不锈钢小冲杆试样断口以穿晶解理断裂为主,部分为准解理断裂;小冲杆试验法是一种有效的应力腐蚀敏感性评估手段,且具有快速近乎无损等特点。 相似文献
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Clarence W.DE SILVA 《Instrumentation》2019,(4):72-84
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... 相似文献
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INTEGRAL EQUATION METHOD'S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES 总被引:1,自引:0,他引:1
LI Cheng ZHENG Yanping 《机械工程学报(英文版)》2008,21(6):115-118
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. 相似文献
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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. 相似文献
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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... 相似文献
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分布动态载荷识别的抗噪处理 总被引:2,自引:2,他引:0
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. 相似文献
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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。 相似文献
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The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar... 相似文献
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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.... 相似文献
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J. A. Williams 《Lubrication Science》1997,3(3):267-306
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. 相似文献
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CHEN Sunyi 《机械工程学报(英文版)》2007,20(6):13-17
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. 相似文献