铋对球墨铸铁低温韧性的影响

研究了铋对球墨铸铁组织和性能的影响,特别是对低温冲击韧性的影响。实验设计了合适的化学成分和含铋量,制定出合理的生产工艺和热处理工艺。利用光谱分析仪、金相显微镜、低温冲击试验机等设备对试样的化学成分、金相组织和力学性能进行了检测和观察。结果显示,适量的铋可以减小石墨球径,增加石墨球数量,提高球铁的低温冲击韧度。铸态下,未加铋的试样低温冲击韧性约在9 J左右。经热处理后,与铸态下加铋试样的低温冲击韧性近似,在12~13 J左右。加铋并热处理后,低温冲击韧性最高可到17 J。另外,随着加铋后石墨球的细化,低温冲击韧度数值波动变小,性能变得更加稳定。     

热处理工艺对GCr15钢碳化物球化效果的影响

分别采用常规球化退火、循环球化退火和1050℃高温固溶+700℃高温回火三种不同的预热处理工艺处理后,再用840℃淬火+150℃回火工艺处理了GCr15钢试样,研究了经上述三种工艺处理后GCr15钢试样的金相组织和硬度,分析了实验结果和球化机理。结果表明:GCr15钢试样经1050℃高温固溶+700℃高温回火+840℃淬火+150℃回火的热处理工艺,具有工艺过程简便、可操作性较强、生产周期较短、能耗较低和强韧性较好的特点,其热处理后的金相组织为回火马氏体+细小、圆整、比较均匀弥散分布的碳化物。     

铜和硅对铸态球铁力学性能的影响规律

研究了铜和硅对铸态球铁井圈基体组织和力学性能的影响,并对铜和硅在铸态球铁中的作用机理进行了分析。制备了铸态球铁试块,测试了试样的力学性能,并观察了材料的金相组织结构。研究表明,在试验范围内,随着铜含量增加和硅含量减少,球铁基体中的珠光体数量增多。当球铁中的铜含量为0.40%~0.60%,硅含量为2.30%~2.70%,基体组织中的珠光体数量达到40%~60%时,可批量生产抗拉强度bσ≥620 MPa、伸长率δ≥10%的铸态球铁井圈铸件。     

热作模具钢的力学性能研究

通过分析在不同热处理工艺下新型热作模具钢沉淀硬化马氏体不锈钢试样的金相组织的变化规律,来研究不同热处理工艺对该沉淀硬化不锈钢的力学行为的影响。     

局部热处理对SPCC冷轧钢压印接头组织及静力学性能的影响

通过组建局部热处理试验装置,对压印接头进行局部热处理,之后制备金相试样,以观察热处理后压印接头的金相组织,检测热处理前与热处理后接头的组织硬度. 并对热处理前与热处理后的压印试件进行拉伸-剪切试验,对比热处理前与热处理后接头的静强度. 结果表明,局部热处理使压印接头部位材料由铁素体与珠光体组织发生转变出现马氏体组织;与前者相比,马氏体组织具有较高的强度与硬度,马氏体组织的这种特征最终使接头静强度得到大幅提升.     

离心铸造高铬合金铸铁气门座圈的组织及耐磨性能研究

采用离心铸造制备两种高铬合金铸铁气门座圈。利用X射线衍射仪(XRD)、金相显微镜、洛氏硬度计和扫描电镜(SEM),对气门座圈铸态及热处理态后的试样物相组成、金相组织、力学性能及拉伸断口形貌进行了观察和分析,同时在销盘式摩擦磨损试验机上对高铬合金铸铁气门座圈的耐磨性能进行了磨损试验。结果表明,热处理前高铬合金铸铁主要为由初生奥氏体、共晶奥氏体和碳化物组成的铸态组织,经淬火及回火处理后转变为马氏体和碳化物组成的组织,明显提高了气门座圈的硬度和强度,由于基体组织和碳化物的形貌及分布改善,高铬铸铁的耐磨性能在热处理后明显提升。     

LPC稀土改性ZG25CrNiMo后耐H2S均匀腐蚀性能

设计了不同含量镧镨铈(LPC)稀土的25CrNiMo铸钢,采用失重法测定了试样在H2S环境中的平均腐蚀速率;并用金相显微镜对铸态试样的腐蚀产物进行了观察分析,结合XPS方法研究了加入稀土前后热处理态试样的腐蚀产物膜表面各元素的化学状态。结果表明,加入LPC稀土的铸态和热处理态试样都达到耐蚀级别,LPC稀土能改变表面铁原子的聚集状态,对25CrNiMo铸钢的确有提高耐蚀性作用。     

含氨试剂防试样污染

一、概述在废品分析、焊接工艺试验、球铁金相检验、低倍酸浸试验及某些多孔疏松型材料(如铁基粉末冶金制品)的金相检验中,常常会出现试样制备完成后,由于裂隙、孔洞中的残存酸液不易冲洗干净而继续污染试样,造成裂隙或孔洞周围污染,甚至波及整个试面,造成观察困难或导致错误的检测结     

铸态铁素体球铁铸件的生产

通过控制铁液合适的化学成分，稳定球化处理工艺，以及加强孕育等措施，成功地实现铸态条件下生产QT450－10铸件，免除了高温热处理工艺，铸件的力学性能和金相组织都符合要求，铸件的综合质量指标也得到提高。     

略论奥贝球铁及其应用

介绍奥贝球铁的特性和使用价值,阐述主要几种合金元素对奥贝球铁热处理和力学性能的影响,分析了奥贝球铁等温淬火热处理规范及工艺过程,对具有高强度、高韧度的奥贝球铁材料的工业应用方面的情况作了介绍。     

彩色金相在金属型磨球凝固分析中的应用

利用彩色金相对过共晶和亚共晶球铁磨球五组试样进行了试验对比。对金属型球铁磨球高温凝固的动态过程及其结晶组织的形态进行了深入分析，讨论了平衡结晶组织与非平衡结晶组织的差异，探讨了金属型球铁磨球非平衡凝固的特性。     

An analysis of induction hardening of ferritic ductile iron

Achievements of the induction hardening of ferritic ductile iron were investigated. Ductile iron is not advisable for use in induction hardening because of the small carbon content in the metal matrix of ferritic ductile iron. The carbon content in the metal matrix of ductile iron can be increased by additional preparation of metal matrix before final induction heat hardening. Wear resistance of the induction hardened ferritic ductile iron can increase as result of increased carbon content of the metal matrix and higher hardness after induction hardening. Some heat pretreatments for metal matrix preparation were applied before the induction hardening of ferritic ductile iron. The process parameters of the induction hardening heat pretreatment were analyzed and optimized. According to recommended elemental composition of ferritic ductile iron and required mechanical properties, the process parameters of the investigated induction heat pretreatment were optimized. The efficiency of pretreatment processes of induction hardening was analyzed. Applicability and manufacture ability of engineering components by proposed heat pretreatments were investigated. The limitations of the investigated heat pretreatment applications were estimated by the comparison of mechanical properties of heat-treated specimens.     

Characteristics of the Transformation of Retained Austenite in Tempered Austempered Ductile Iron

Controlling the amount of retained austenite is a concern in austempered ductile iron formation. Retained austenite has a strong influence on austempered ductile iron properties, such as hardness and wear resistance. In this research, the characteristics of the transformation of retained austenite were investigated as a function of the number of tempering cycles. The hardness of the austempered ductile iron samples was measured, and the specific amount of retained austenite was analyzed by x-ray diffraction (XRD). Wear tests were conducted on a ball-on-flat sliding fixture. The tempering process was found to have no effect on the hardness of the austempered ductile iron samples. This may be due to retained austenite being partially converted into brittle quenched martensite during the tempering process. However, tougher tempered martensite was also formed from existing martensite. The two effects seemed to offset each other, and no significant differences occurred in overall hardness. XRD analysis showed that under the same austempering temperature and holding time, the amount of retained austenite decreased with additional tempering cycles. Also, with the same holding time and tempering cycles, less retained austenite was contained in the matrix at higher austempering temperatures. This was due to more high carbon content austenite and needle-like ferrite being present in the austempered ductile iron matrix. In addition, tempered austempered ductile iron exhibited significantly higher wear resistance as compared to traditionally treated ductile iron.     

激光熔覆巴基管／球墨铸铁的研究

本文以巴基管为涂层，采用激光熔覆并辅以后续热处理的方法，对珠光体球墨铸铁进行改性处理，所得样品的表面硬度达ＨＲＣ６５。观察电镜（ＳＥＭ）观察表明，样品的组织主要为马氏体及网状碳化物，同时，产生了具有规则几何形状的晶体，它的形成与马氏体的转变有关。     

连续冷却淬火球墨铸铁的性能研究

研究了连续冷却淬火球墨铸铁的组织与性能。结果表明:采用适当的化学成分,选择合适的淬火介质,可用连续冷却淬火获得奥贝组织的球铁,其硬度达54HRC,冲击韧度为21 J·cm(-2),相对耐磨性为淬火马氏体低合金钢的2.17倍。     

EFFECT OF SILICON ON PRODUCING DUCTILE IRON WITH COMPLEX STRUCTURE OF BAINITE AND MARTENSITE

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汽车球铁件凝固数值微机模拟技术开发与应用

利用微机对球墨铸铁件的凝固过程进行三维数值模拟,并用彩色图形显示其动态凝固过程,其计算结果可为汽车球铁件的工艺参数优化提供科学依据。     

冲压模具激光表面强化的搭接工艺研究

针对激光相变强化搭接带存在的回火软化等问题,对激光强化的球墨铸铁材料QT700-2搭接区的显微硬度、表面粗糙度、物相变化等进行了测试,并分析了强化机理。结果表明:选用合理的搭接率等工艺参数,球墨铸铁激光搭接强化后的硬度可达到50HRC以上,调节搭接宽度可以避免搭接区的回火软化问题。多道搭接强化后表层的马氏体组织呈区域性交错分布,材料表面形成非均匀、多尺度强化结构,强化后的表面具有良好的耐磨性和耐疲劳性。通过上述结果,对材料激光搭接强化的工艺参数进行了合理的优化。     

A study of several factors governing the fatigue limits of austempered ductile cast iron with various microstructures

The effects the leading factors bearing on fatigue limits were investigated with three kinds of ductile iron specimens various microstructures. As a result of examination, the fatigue limits in relationship to hardness and tensile strength, the expected higher improvement for fatigue limits in the case of the high strength specimens that experienced austempering treatment are not observed in comparison with the specimens treated with stress relief treatment. The estimated maximum defect size is one of the important parameters in predicting and evaluating fatigue limits for three different heat-treated ductile cast irons. Also, a quantitative relationship can be established between the fatigue limit and maximum defect size. Moreover, it is possible to explain the difference in fatigue limits in the three ductile cast irons by application of the rates of non-propagating crack which connects the adjacent graphite nodules before it stops.     

Effect of sub-zero cooling on microstructure and mechanical properties of a low alloyed austempered ductile iron

The effect of sub-zero cooling on microstructure and mechanical properties of a low alloyed austempered ductile iron has been investigated. Austempering of samples was performed at 325℃and 400℃after austenitizing at 875℃and 950℃. The sub-zero treatments were carried out by cooling down the samples to -30℃, -70℃and -196℃. The changes in volume fraction of austenite and mechanical properties were determined after cooling to each temperature. The austenite volume fraction of samples which were austenitized at 875℃and austempered at 325℃remained unchanged, whilst it reduced in samples austenitized at 950℃and 875℃for austempering temperature of 400℃. In these specimens, some austenite transformed to martensite after subzero cooling. Mechanical property measurements showed a slight increase in strength and hardness and decrease in elongation and toughness due to this transformation behavior.