奥贝球铁的现状与发展趋势

在综合大量文献资料的基础上，论述了奥贝球铁的研究和应用现状，阐述分析了存在的问题，指出了解决的途径和发展趋势。     

奥－贝球铁断裂与疲劳研究的新近进展

奥 -贝球铁具有很强的强度、塑性、韧性、疲劳强度和耐磨性等综合性能 ,应用日益广泛 ,已成为一种重要的工程材料。近年来对其断裂与疲劳的研究发展很快 ,得到不断的深入 ,本文详细介绍了其新近进展。     

等温淬火对奥贝球铁上贝氏体转变动力学的影响

本文研究了等温淬火过程中奥氏体化温度和等温淬火温度对奥贝球铁上贝氏体第一阶段转变速度的影响及其机制；观察与测定了不同等温转变时奥贝球铁的组织与性能。结果表明，升高奥氏体化温度和等温淬火温度，使上贝氏体第一阶段转变速度减慢，在该转变结束时，奥贝球铁组织与性能最稳定。     

Characterization of Dual-Phase Steels Using Magnetic Barkhausen Noise Technique

The aim of this work is to nondestructively characterize the dual phase steels using the Magnetic Barkhausen Noise (MBN) method. By quenching of AISI 8620 steel specimens having two different starting microstructures, from various intercritical annealing temperatures (ICAT) in the ferrite-austenite region, the microstructures consisting of different volume fractions of martensite with morphological variations have been obtained. The microstructures were first conventionally characterized by metallographical investigations and hardness tests. Then, the MBN measurements were performed using a μSCAN commercial system. Good correlations between the martensite volume fraction, hardness and MBN emission have been obtained. MBN signal height clearly decreased as the ICAT, therefore the volume fraction of martensite increased. The effect of the initial microstructure prior to intercritical annealing has also been differentiated by the MBN measurements. It has been concluded that MBN method can be used as a useful tool for nondestructive characterization of dual phase steels.     

硅对连续冷却贝氏体球铁的影响

探讨含铬、钼、铜多元微量元素的合金球铁经连续冷却获得贝氏体组织的新工艺中,硅对热处理工艺参数、球铁显微组织和强韧性能的影响.结果表明,硅对奥氏体化工艺参数影响显著,硅量在2.6%～3.3%(质量分数)时,可以稳定地获得以下贝氏体为主的组织和良好的力学性能(HRc＞50,冲击韧度＞10J/cm2).     

Effect of Ball Scribing on Magnetic Barkhausen Noise of Grain-oriented Electrical Steel

Effect of ball scribing on magnetic Barkhausen noise(MBN) of conventional grain-oriented(CGO) and highpermeability grain-oriented(HGO) electrical steel was investigated.The results showed that after ball scribing, root mean square of MBN(MBNrms) of CGO electrical steel increased 9.8%with 4 mm scribing spacing at 1.2 T,and that of HGO electrical steel apparently decreased 17.3%with 16 mm scribing spacing at 1.2 T. Through the formation and development of free magnetic poles and secondary magnetic domains due to compressive stress,primary magnetic domain space of grain-oriented electrical steel becomes smaller,which reflects as a variation of MBN in the macroscopic magnetic properties.Through correlation formula derivation of MBNrms and equilibrium distance between domain walls,effect of domain refinement on grain-oriented electrical steel was also interpreted,and optimum equilibrium distance between domain walls was determined.     

球墨铸铁机械性能的优化模型

通过对球墨铸铁机械性能影响因素的分析,指出在一定的生产条件下,球墨铸铁的机械性能主要取决于组织、成分。利用Matlab中的Neural Network Toolbox仿真环境和BP模型算法建立了球墨铸铁机械性能的优化模型,详细论述了模型结构的设计、数据处理、网络初始化、训练与仿真的过程。该方法对提高球墨铸铁的机械性能具有积极作用。     

Monitoring the Microstructural Changes During Tempering of Quenched SAE 5140 steel by Magnetic Barkhausen Noise

The aim of this work is to characterize the microstructures of quenched and tempered steels non-destructively by a diverse set of parameters of the Magnetic Barkhausen Noise method (MBN fingerprint, frequency spectra, pulse height distribution, root-mean-square, and total number of pulses). Identical specimens from a SAE 5140 steel bar were prepared. All specimens were austenitized at 860°C for 30 minutes and water-quenched identically. The quenched specimens were then tempered at various temperatures between 200°C and 600°C. The microstructures were characterized by metallographic examinations and hardness measurements. Pulse height distributions, noise signal envelopes and frequency spectra were used to evaluate Barkhausen activity. The results show that as the tempering temperature increases, the Barkhausen activity increases due to the enhancement of domain wall displacement with softening of the martensite. An excellent correlation was found between Barkhausen parameters and hardness values.     

磁巴克豪森噪声检测材料疲劳的励磁频率优化研究

磁巴克豪森噪声在铁磁性材料早期疲劳损伤的检测中具有巨大的应用潜力.在疲劳检测过程中,励磁频率作为磁巴克豪森噪声的激发源,对检测结果有重要影响.实验研究励磁频率对磁巴克豪森噪声检测铁磁性材料疲劳时检测结果的影响规律,以20R钢材料为对象进行低周疲劳实验,并在励磁频率分别为9,16,35,60?Hz下对取自同一母材的3个试...     

Ni对球墨铸铁热处理的影响

采用电子探针，图象分析仪、差质变分析仪和Ｘ射线衍仪定量研究了Ｎｉ在球铁中的分布和Ｎｉ铸态球铁组成相比例奥氏体中含碳量以及贝氏体转变ＴＴＴ曲线线的影响，结果表明，Ｎｉ在球铁中呈连续负偏析，其加入可以影响球铁组成上比例，并使粤氏体中含碳量和贝氏体转变孕育期期增加。     

铸态球墨铸铁阀体铸件的生产试验

在分析化学成分对铸态球墨铸铁影响的基础上,通过采用低稀土球化剂、使用盖包法球化处理以及复合孕育工艺等一系列措施,成功实现了完全铸态条件下球墨铸铁件的生产。该方法无需对铸件进行热处理,提高了生产效率,降低了铸件生产成本,改善了生产环境。     

热浸镀铝球墨铸铁失效机理研究

采用VK-9710型激光共聚焦显微镜对热浸镀铝球墨铸铁试样的三点弯曲失效过程进行原位观察,分析镀层和基体的裂纹萌生和扩展机理。结果表明:对于纯Al浸镀球墨铸铁,在拉应力作用下,铁铝合金镀层率先萌生裂纹,诱导临近基体中铁素体撕裂与石墨球剥离,裂纹近似垂直于拉应力方向并沿着临近石墨球最短途径扩展;压应力导致表面纯Al层剥离和铁铝合金层破碎,镀层失效对球墨铸铁基体基本无影响。对于Al-3.7Si-1.0RE浸镀球墨铸铁,拉应力作用下的失效机理与纯Al浸镀相似;压应力作用下纯Al层和铁铝合金层与基体脱开,表现为铁素体基体失效。     

马氏体基体含碳量对马氏体球铁磨损性能的影响

针对马氏体球铁,研究了马氏体基体不同含碳量(不同奥氏体化温度)对两体磨损和冲击磨料磨损耐磨性的影响。结果表明:在软磨料作用下的高应力两体磨损中,马氏体球铁以疲劳机制破坏,硬磨料作用下以切削机制破坏;在有较大冲击载荷作用的动载磨料磨损中,马氏体球铁存在有抗冲击疲劳剥落的最佳马氏体含碳量;石墨球的存在对耐磨性有害。     

A study of austenitization of SG iron

Austenitization process of three SG irons with varying compositions and as cast matrix microstructure has been studied at three austenitization temperatures of 850, 900 and 950C for different time periods. Microstructure, hardness and X-ray diffraction have been used to reveal the nature of dependence of the process on austenitization temperature, time and as cast structure. The optimum austenitization time is maximum for ferritic and minimum for pearlitic matrix.     

Nondestructive evaluation of cementite content in steel and white cast iron using inductive Barkhausen noise

A nondestructive testing method for the determination of the cementite content in iron-carbon steel and white cast iron is presented. The method is based on micromagnetic measuring parameters derived from inductive Barkhausen noise measurements taken under room temperature and with temperatures above the Curie temperature. The influence of different cementite contents and cementite modifications on the micromagnetic measuring quantities for steels with ferritic, pearlitic, martensitic annealed and martensitic soft annealed microstructure states and for white cast iron was determined. Cementite actively produces its own inductive Barkhausen noise and also influences the Barkhausen noise of the iron matrix both as a foreign body and by its stress fields of the second kind. Each influence has a different effect on steel and on white cast iron. It was shown that parameters derived from the Barkhausen noise can be used for determining the cementite content if the microstructure state is known. Moreover, when the steel grade is known, the microstructure state can be detected from the pattern of the Barkhausen noise curve by means of simple pattern recognition.This paper is dedicated to Prof. Dr. phil. Paul Hoeller ( Feb. 21, 1996), former director of the IZFP. Prof. Hoeller supported especially the scientific research work described in this article.     

球铁渗硫软氮化耐磨性研究

对球铁进行了渗硫软氮化试验，分析结果表明，在工件表面上形成一层很薄的多孔化合物层。文中除了找出最佳渗硫软氮化工艺方案外，对提高耐磨性机理进行了初步分析。     

热等静压处理对球墨铸铁疲劳性能的影响

研究了球墨铸铁材料(EN-GJS500-7)热等静压处理前后疲劳性能的变化,并分析了珠光体、石墨、铁素体含量随热等静压工艺的变化及其对球墨铸铁疲劳性能的影响。结果表明,热等静压处理后如果珠光体含量增加而铁素体含量减少,则材料抗疲劳性能增强;反之,材料疲劳性能降低。     

含硼低合金球铁磨球的研制

研究了一种能在冲天炉条件下生产的用于制造磨球的低合金球铁材料。通过加入微量的硼元素及少量的铬元素提高了碳化物的显微硬度,通过采取一定的热处理方式改变了碳化物的形态,耐磨球铁的组织为:球状石墨+小块状碳化物+针状组织。含硼低合金耐磨球铁的硬度为HRC52～58,冲击韧性可达9～11J/cm~2.     

等温淬火球墨铸铁滚动磨损与损伤性能

利用不同热处理方式和球化工艺,获得两种显微组织和不同硬度的等温淬火球墨铸铁(Austempered Ductile Iron,ADI)材料,利用MMS-2A微机控制摩擦磨损试验机对比研究了两种等温淬火球墨铸铁材料、车轮材料与U71Mn钢轨匹配时的滚动磨损与损伤性能。结果表明:ADI材料与U71Mn钢轨匹配时的摩擦因数明显小于车轮材料;由于ADI材料具有自润滑效果导致其磨损率明显小于车轮材料,ADI材料的自润滑性能也降低了对摩副U71Mn钢轨的磨损率,其中含有较大球状石墨和较少残余奥氏体的ADI2材料和对摩副U71Mn钢轨的磨损率最小;ADI材料的磨损机制主要表现为轻微疲劳磨损,对摩副U71Mn钢轨的磨损机制主要表现为黏着和轻微疲劳磨损,而轮轨材料匹配时的塑性流动层显著,损伤以表面疲劳裂纹和剥层损伤为主。