双淬火+深冷处理工艺对Cr12Mo1V1模具钢组织和性能的影响

对退火态Cr12Mo1V1模具钢分别进行一次淬火+回火、双淬火+回火、一次淬火+深冷+回火、双淬火+深冷+回火等工艺处理,其中一次淬火工艺为1 030℃×0.5 h油淬,双淬火工艺为1 050℃×0.5 h油淬+1 030℃×0.5 h油淬,深冷处理工艺为-60℃×1 h+-120℃×1 h,对比研究了双淬火+深冷处理对试验钢显微组织和力学性能的影响。结果表明:与一次淬火+回火工艺相比,双淬火+回火工艺可以改善共晶碳化物分布均匀性,使碳化物形态趋于球状;增加深冷处理对改善共晶碳化物形态和均匀度的效果不明显,但可降低残余奥氏体含量。双淬火+回火工艺处理后试验钢的硬度与一次淬火+回火处理后相近,但冲击吸收能量和抗弯强度分别提升22%和12%;增加深冷处理对试验钢硬度、冲击韧性和抗弯强度影响不大。     

淬火温度和回火工艺对4Cr5Mo2V钢高温耐磨性能的影响

将4Cr5Mo2V钢在1 000～1 090℃下淬火,并通过不同温度2次回火处理将相同淬火温度下试验钢的回火硬度分别调整至55,52 HRC,研究了淬火温度和回火工艺对显微组织、冲击韧性和高温(350℃)耐磨性能的影响。结果表明：回火硬度相同时,淬火温度过高或过低均会降低试验钢的韧性而加剧磨损表面材料剥落,从而降低耐磨性能;相同回火硬度下,1 030℃淬火条件下试验钢的韧性和高温耐磨性能最好,1 090℃淬火条件下最差;淬火温度相同时,较低温度回火试验钢因具有较高回火硬度,能够起到支撑表面氧化层的作用,其耐磨性能比较高温度回火时好;4Cr5Mo2V钢的推荐热处理工艺为1 030℃×30 min油淬+560℃×2 h×2次回火。     

碳含量对4Cr5Mo2V热作模具钢显微组织及热稳定性的影响

对不同碳含量的4Cr5Mo2V钢进行淬火+回火热处理,研究了碳含量(0.35%,0.47%,0.71%,质量分数)对其显微组织、碳化物演变规律和热稳定性的影响。结果表明:在1 030℃淬火后,碳质量分数为0.35%的试验钢中无碳化物,碳质量分数为0.47%,0.71%的试验钢中存在颗粒状富钒MC型碳化物;淬火+回火处理后,试验钢中均析出M_(23)C_6碳化物,随碳含量增加,M_(23)C_6碳化物增多;进行热稳定性试验后,碳化物大量析出并发生粗化,随热稳定保温时间缩短和碳含量增加,试验钢硬度增大,热稳定性增强;碳含量增加能够提高试验钢的回火转变激活能,碳元素的固溶强化作用与MC型碳化物的析出强化作用是钢热稳定性增强的主要原因。     

热处理工艺对工程机械用1000MPa级高强钢组织与性能的影响

对工程机械用1 000MPa级高强钢进行不同温度的淬火和回火热处理,研究了热处理工艺对其力学性能和显微组织的影响,并得到了试验钢较佳的淬火和回火温度。结果表明:随着淬火温度升高,试验钢的强度先增大后降低,并在900℃时达到最大;830℃以下淬火后,组织中存在未溶铁素体,组织为铁素体和板条马氏体;900℃以上淬火后,组织为板条马氏体;随着回火温度的升高,试验钢的强度下降,塑、韧性提高,当回火温度达到450℃以上时,组织转变为回火索氏体,冲击韧性大幅提高;较优的热处理工艺为900℃淬火后在500℃回火。     

淬火温度对车轴管用XCQ16-1钢组织和性能的影响

对车轴管用XCQ16-1钢进行了不同温度淬火和相同温度回火的热处理,测定了其力学性能,并用OM和SEM对热处理后钢的显微组织和断口形貌进行了观察,分析了淬火温度对其组织和性能的影响机理。结果表明:在840~910℃的温度淬火对XCQ16-1钢屈服强度、抗拉强度和硬度的影响不大,而对伸长率和冲击功的影响较大;860℃淬火后该钢具有良好的综合力学性能,可满足车轴管钢的要求;860℃淬火+490℃回火后该钢的显微组织为回火索氏体,冲击断口具有韧性断裂特征。     

热处理工艺对14Cr1MoR钢组织性能及腐蚀行为的影响

采用扫描电镜、透射电镜和电化学工作站,分析了控轧+回火、淬火+回火、正火+回火不同热处理工艺对14Cr1MoR钢显微组织、力学性能和腐蚀行为的影响。结果表明：控轧+回火和正火+回火后,试验钢的显微组织由多边形铁素体和贝氏体回火组织构成,但相比例不同。淬火+回火后,试验钢的显微组织为回火索氏体,该热处理工艺下的14Cr1MoR钢室温和高温强度最高,韧性最佳。耐蚀性能方面,淬火+回火态试验钢最佳;其次为正火+回火态试验钢;控轧+回火态试验钢最差。     

淬回火工艺对N-Mo合金化Cr13型耐蚀塑料模具钢组织与力学性能的影响

对N-Mo合金化Cr13型耐蚀塑料模具钢进行925～1 150℃保温0.5 h的油淬处理,再分别进行150～300℃保温2 h或者350～600℃保温1 h的回火处理,研究了淬回火工艺对该钢组织与力学性能的影响。结果表明：试验钢淬火后的组织主要为淬火马氏体,随着淬火温度的升高,晶粒长大,第二相逐渐固溶进基体,试验钢的硬度先增大后降低,当淬火温度为1 050℃时,硬度达到峰值,为57.7 HRC,此时第二相基本固溶进基体,残余奥氏体体积分数仅为8.49%。随着回火温度的升高,试验钢组织由回火马氏体向索氏体转变,第二相逐渐析出并长大;硬度呈先降低后升高再迅速降低的趋势,冲击吸收能量随回火温度的变化规律与回火硬度的变化规律相反,抗拉强度的变化规律与硬度的变化规律一致,屈服强度呈先增大后降低的趋势,并在回火温度为480℃时达到最大值,为1 445 MPa;在200℃以上温度回火后试验钢的塑性均保持在一个较好的水平。试验钢获得优异综合性能的热处理工艺为1 050℃×0.5 h淬火+200～300℃×2 h回火,此时组织为回火马氏体,硬度为48～53 HRC,抗拉强度为1 752～2 050 MP...     

热处理工艺对SDC90新型冷作模具钢组织与性能的影响

为了确定SDC90新型高强韧冷作模具钢的热处理工艺,采用光学显微镜、洛氏硬度计和冲击试验机等对其显微组织、硬度和冲击性能进行了研究,并与Cr12MoV钢进行了对比。结果表明:SDC90钢中的莱氏体、碳化物比Cr12MoV钢的更细小、分布更均匀;经1 040℃淬火和210℃回火后,其硬度与Cr12MoV钢的相当,而冲击功却是它的2倍;该钢经1 080℃淬火和540℃回火后,其硬度和冲击功均高于Cr12MoV钢的;该钢的高硬度与良好的强韧性配合可大大提高模具的使用寿命。     

GGr15钢的锻后热处理方案设计

介绍了锻造后GGr15钢的一套完整热处理工艺方案,其工艺过程为：1）预先热处理,780℃球化退火0.5h,炉冷至659℃后出炉空冷,710℃等温退火710℃,保温2h,空冷;2）最终热处理,840℃淬火0.5h,出炉,机油冷却,油温30~60℃,150℃回火2h,空冷,120℃补充回火3h,空冷。对热处理后试验用钢的硬度以及显微组织进行分析可知,其硬度〉63HRC,达到了使用要求。     

S290粉末高速钢高硬度丝锥的盐浴淬火工艺研究

高碳、高合金和高碳饱和度是S290粉末高速钢的成分特点。采用合理的淬火和回火工艺能得到高硬度,并且不容易磨裂。淬火温度对S290钢淬回火硬度影响不明显,但对其过热程度和强度影响明显。S290钢高硬度丝锥适宜的淬火温度为1190℃～1210℃,回火工艺为560℃×1h×2次+550℃×1h×1次,S290钢淬火加热时间略短于M2钢。为保证S290钢的淬回火硬度和韧性,S290钢的淬火冷却速度应比M2钢更快。     

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.