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。     

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。     

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。     

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。     

电脉冲调质处理对齿套用35CrMo钢显微组织和 力学性能的影响

在不同回火温度(550～640℃)、不同脉冲次数(1,2次)和脉冲持续时间(60～180ms)下对热轧态35CrMo钢分别进行传统淬火+传统回火、电脉冲淬火+传统回火、传统淬火+电脉冲回火处理,对比研究了处理后的显微组织和力学性能。结果表明:电脉冲淬火+550℃传统回火、传统淬火+1次电脉冲回火以及传统淬火+2次电脉冲60ms回火处理后,试验钢的组织与传统淬火+传统回火处理后的相似,均由马氏体和碳化物组成;随着回火温度的升高,电脉冲淬火+传统回火处理后的组织中出现层片状索氏体,试验钢的抗拉强度和硬度降低,伸长率增大;电脉冲淬火或回火均能提高试验钢的强塑性,电脉冲淬火+580℃传统回火处理后的强塑性最佳。     

热处理温度对高钒高速钢显微组织和硬度的影响

研究了淬火温度和回火温度对高钒高速钢显微组织和硬度的影响.结果表明:在空冷条件下,当淬火温度低于1 040℃时,随着淬火温度的升高,钢的硬度逐渐升高;超过1 040℃后,随着淬火温度的升高,其硬度又逐渐降低;同时随着淬火温度的升高,钢中碳化物的数量逐渐减少,马氏体不断粗化,而残余奥氏体含量逐渐增加;在1 040℃淬火后,当回火温度低于500℃时,钢的硬度变化不明显;超过500℃后随着回火温度的升高,其硬度先升高,并在520℃时达到最高值,此后钢的硬度又逐渐降低;随着回火温度的升高,马氏体中弥散析出的碳化物数量逐渐增加并聚集长大,同时马氏体和部分残余奥氏体转变为回火马氏体.     

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...     

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。     

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。     

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.     

Fifth International Summer School on Screw-Theory Based Methods in Robotics

正3-11 September,2014University of Bologna,Bologna,Italy www.summerscrews.org summerscrews2014.ing.unibo.it SUMMER 20SCREWS 14In 2014,our screw-theory school comes to the world's oldest university.In early September,Summer Screws'14 will gather six experts in the application of screw theory in robotics and up to 40 participants at the University of Bologna,Bologna,Italy.The school will teach attendees how to apply existing methods and empower them to develop new ones in their own research.The basic theoretical notions will be introduced in a rigorous manner,emphasizing examples,applications,and exercises.Scholarships are available.     

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。     

INDUSTRIAL ENGINEERING AND VISUALISATION-A PRODUCT DEVELOPMENT PERSPECTIVE

Taking the actual project of teaching and researching process for example, the relationship between the industrial engineering and product development is discussed. And use the novel visualization technology to support the industrial engineering and product development. How to use the new computer modeling and simulating technologies to support the product development and industrial engineering, is introduced especially. The support includes both domestic products and industrial systems. The visualization and computer technologies take a very important role in some system or multi-direction modeling, those technologies mentioned above can help the industrial engineers study the effect of design on the whole life circle, including the producing steps. So the engineers can avoid making the wrong decision which may cause bad effects on the whole industrial engineering.     

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...