铸态QT550-7球墨铸铁制备及组织研究

为了研究铸态QT550-7球墨铸铁组织,铁液凝固过程及石墨球化机理,用回炉铁、生铁、废碳钢、球化剂、孕育剂等材料,采用双联熔炼法制备了球墨铸铁.经测试,化学成分和力学性能满足QT550-7球墨铸铁要求,球墨铸铁组织由铁素体+珠光体+球状石墨组成,凝固过程为糊状凝固.     

稀土蠕墨铸铁基体组织的试验总结

从目前所发表的国内外文献来看,尚不能在铸态条件下获得全珠光体组织,而且也缺乏这方面的系统试验研究。本文作者在实验室条件下,通过近二百炉次的试验,研究了 C、Si、Mn、Cr、Mo、V、Sb、Sn、B、Nb 和 W 等元素对石墨形态和基体的影响,并把这些元素对基体组织的影响进行分类、探索了获得珠光体基体蠕虫状石墨铸铁化学成分选择的原则。试验结果表明:适当地调正碳当量,加入一定量的锰或其他合金元素可以在铸态基体组织中稳定地获得90%以上的珠光体。这种合金蠕墨铸铁的抗弯强度达90kg/mm~2,抗拉强度达43～47kg/mm~2,挠度,4～6mm,布氏硬度249Hs(在φ30mm 试棒上测定)。     

一种提高GCr15钢冷冲模具使用寿命的新工艺

1前 言 我们根据GCr15钢冷冲模具的服役条件,进行了GCr15钢高温固溶和循环加热淬火双细化工艺试验,分析对比了不同的工艺参数及热处理效果,并在生产中进行了验证。2 试验材料及方法2.1试验用钢及冶金质量 试验用GCr15钢化的化学成分如表1,冶金质量见表2,原始组织为球化退火组织。表1 试验用钢的化学成分化学元素CCrSiMnSP含量（%）1.041.620.240.280.0040.009表2 冶金质量检查球状珠光体碳化物不均匀性非金属夹杂物网状带状氧化物硫化物点状2级<2级<2级1级1.5级1级2.2热处理工艺2.2.1工艺A: 预处理是将φ16×15mm试样加热至104…     

基于BP神经网络的球墨铸铁组织和力学性能预测

以合金化元素与组织和性能关系为研究对象,从42组实验数据中,选取33个作为训练样本,9个作为验证样本,采用BP神经元网络原理,以珠光体球墨铸铁组织和力学性能的主要影响元素作为输入量,模型由3层神经元组成,分别为输入层、隐含层和输出层,建立了合金成分对珠光体含量的影响规律的神经网络模型,珠光体含量、铁素体含量及球化率和硬度及强度关系的神经元网络模型.用建立的网络模型预测结果表明,该方法对球墨铸铁的珠光体含量和力学性能预测具有很好的准确性,有效地解决了球墨铸铁化学成分、显微组织与力学性能之间的关系难于描述的问题.     

后桥主减速器壳体轴承座材料裂解性能数值分析

对基体组织为25%P+75%F和50%P+50%F的后桥主减速器壳体轴承座材料QT450的显微组织进行比较,以研究组织与裂解性的内在联系.首先,对不同金相组织的QT450试件进行拉伸试验,获取数值模拟所需的材料参数,并与模拟相结合,分别确定两种基体组织的临界断裂韧度J_(IC),利用ABAQUS模拟获得不同显微组织的QT450的裂解载荷及应力集中程度;然后建立回弹模型,分析两种组织的塑性变形及失圆;最后进行裂解试验对数值分析的有效性进行验证.结果表明:基体为50%珠光体+50%铁素体的QT450相比基体为25%珠光体+75%铁素体的QT450更适于裂解;QT450材料的强度和刚度取决于珠光体的含量,随珠光体含量的上升,材料的脆硬性好,缺口敏感性好,其裂解性能更佳;采用基体组织为25%珠光体+75%铁素体的QT450生产的轴承座的失圆度大于0.2 mm,无法完成后续精加工及装配,而采用基体组织为50%珠光体+50%铁素体的QT450材料生产的轴承座的失圆度小于0.2 mm,裂解产生的塑性变形小,更符合实际生产的工艺要求.     

低合金钢双辉渗W-Mo-Co初探

利用双层辉光离子渗金属技术在低合金钢25Cr2Mo2V表面渗W—Mo—Co三元合金，可在表面形成铁、钴、钨、钼时效合金。研究了形成这种合金的表面冶金工艺和渗层组织状态，渗层成分分布以及工艺参数的改变对渗层厚度及渗层成分的影响。结果表明，表面合金元素的含量可以达到高钴时效合金W11Mo7Co23的水平。     

铁-铬-镍系耐热合金的焊接工艺分析

耐热高温合金广泛应用于航空航天、船舶等行业,其焊接技术和焊接性能一直是研究的重点.分析了铁-硌-镍系的Incoloy800耐热合金、铸造耐热不锈钢炉管(HK-40)和HP45NbTi铸造耐热不锈钢的化学成分,结合所选用的焊接材料,讨论了这三种耐热合金适宜的焊接工艺.     

服装纽扣用锌铜钛合金带材的研制

通过研究锌-铜-钛合金带材中铜、钛等合金元素的合理控制以及轧制变形工艺与退火工艺的优化控制,根据服装纽扣等五金制品的使用要求,提出了服装纽扣等五金制品用锌-铜-钛合金带材合理的化学成分及生产工艺,并批量生产出锌-铜-钛合金带材,用于代替黄铜带材生产服装纽扣等五金制品.     

镍、铬对D型石墨铸铁基体组织的影响

文章研究了加入不同量合金元素镍、铬对D型石墨铸铁基体组织的影响。研究结果表明:微量合金元素镍、铬的加入都有细化珠光体的作用,在某种程度上随着合金元素镍和铬加入量的增加细化作用越大;加入合金元素镍或铬都能提高D型石墨铸铁基体的硬度,随着合金元素加入量的增大,硬度值亦随之增大;当合金元素加入量超过0.6%后,硬度值减小。     

机用锯条双层辉光离子渗金属、离子渗碳后的研究

针对机用锯条存在消耗合金元素、碳化物分布不均匀、冶金困难和工艺复杂等问题，利用双层辉光渗金属技术形成的表面冶金高速钢可以达到良好的综合机械性能。本研究用20Cr2V2机用锯条坯材作为试样进行双层辉光离子渗金属和离子渗碳，对渗金属、渗碳后的金相、XRD图谱进行分析，为表面高速钢机用锯条的工业化推广进行了有益的探索。     

球墨铸铁中渗碳体球化的影响

The research aims to provide an alternative to austempering treatment of ductile cast iron with a simple and cost-effective heat-treatment process. This goal was accomplished by applying a simple one-step spheroidization heat treatment to the as-cast ductile iron, which would normally possess a coarse pearlitic microstructure to a significant extent. Spheroidization experiments involving isothermal holding below the lower critical temperature (A1) were conducted followed by standard mechanical testing and microstructural characterization for an experimental ductile iron. After improving the spheroidization holding time at a given temperature, the work shows that the ductility and toughness of an as-cast ductile iron can be improved by 90% and 40%, respectively, at the cost of reducing the tensile strength by 8%. Controlled discretization of the continuous cementite network in pearlitic matrix of the ductile iron is deemed responsible for the improved properties. The work also shows that prolonged holding time during spheroidization heat treatment leads to degradation of mechanical properties due to the inhomogenous microstructure formation caused by heterogeneous decomposition and cementite clustering in the material. The main outcome of this work is the demonstration of ductile cast iron’s necking behavior due to spheroidization heat treatment.     

Effect of spheroidization of cementite in ductile cast iron

The research aims to provide an alternative to austempering treatment of ductile cast iron with a simple and cost-effective heat-treatment process. This goal was accomplished by applying a simple one-step spheroidization heat treatment to the as-cast ductile iron, which would normally possess a coarse pearlitic microstructure to a significant extent. Spheroidization experiments involving isothermal holding below the lower critical temperature(A1) were conducted followed by standard mechanical testing and microstructural characterization for an experimental ductile iron. After improving the spheroidization holding time at a given temperature, the work shows that the ductility and toughness of an as-cast ductile iron can be improved by 90% and 40%, respectively, at the cost of reducing the tensile strength by 8%. Controlled discretization of the continuous cementite network in pearlitic matrix of the ductile iron is deemed responsible for the improved properties. The work also shows that prolonged holding time during spheroidization heat treatment leads to degradation of mechanical properties due to the inhomogenous microstructure formation caused by heterogeneous decomposition and cementite clustering in the material. The main outcome of this work is the demonstration of ductile cast iron's necking behavior due to spheroidization heat treatment.     

马氏体球墨铸铁磨球的研制

在生产条件下研究了马氏体磨球的生产工艺和性能。通过淬火和低温回火处理获得了马氏体基体组织，冲击值达５～７Ｊ／ｃｍ２，硬度为ＨＲｃ５３～５８，含磷量可以放宽到０．１４％。马氏体球、墨铸铁磨球的生产成本与中锰球墨铸铁磨球相当，但机械性能明显地优于后者。     

运用均衡理论改进D6110ZQ型柴油机曲轴铸造工艺

运用均衡凝固理论,分析改进D6110ZQ曲轴铸造工艺,结果表明合理地设置冷铁,可以减少曲轴的缩孔或缩松缺陷,或者可使缩孔移至不影响曲轴性能的中心部位;选择适合的冒口颈尺寸,利用冒口颈的自适应调节的作用,利用冒口补缩曲轴本身自补不足的差额,是解决曲轴缩孔缩松的有效途径之一;在QT900-3牌号要求的化学成份范围内,铜、钼合金元素是否加入对D6110ZQ曲轴缩孔缩松的产生影响不大;对于类似D6110ZQ曲轴结构的球铁件,在符合一定的条件下,可认为冒口补缩距离在理论上不受限制。     

离心奥氏体──贝氏体球墨铸铁管

比较系统地研究了合金元素Ｃｕ、Ｍｏ和等淬时间及温度对离心奥氏体／贝氏体球墨铸铁管组织与性能的影响，找出了合金元素Ｃｕ、Ｍｏ对离心奥氏体／贝氏体球墨铸铁管的影响规律，确定了适宜的热处理工艺参数，并在实验室生产出性能良好的离心奥氏体／贝氏体球墨铸铁管。     

铁素体球墨铸铁低温冲击韧性

为了优化生产工艺,探究化学成分对低温冲击韧性影响规律,通过夏比冲击试验方法研究了3组铸态全铁素体球墨铸铁的低温冲击韧性,分析了硅、碳含量对低温冲击韧性影响及断口形貌。结果表明：3组试样中,冲击韧性随碳含量增多和硅含量降低而升高;冲击韧度值随着温度的降低而下降,-20℃下可以达到15.20 J,冲击韧度值在温度低于-40℃后变化不大,韧脆转变温度在-40℃以上。冲击断口形貌表明,随温度降低,球墨铸铁的断裂机制由韧性断裂转为韧脆混合断裂,最后变为脆性断裂。可见碳硅含量会对低温冲击韧性造成一定影响。     

二次孕育及终硅量对铸态铁素体球墨铸铁组织性能的影响

将铸态球墨铸铁经退火处理生产铁素体球墨铸铁的工艺复杂、周期长。本研究进行了调整终硅量及釆用二次瞬时孕育处理工艺直接得到铸态铁素体球墨铸铁的试验。结果表明,釆用稀土镁球化剂和硅铁孕育剂,对铁液进行立即孕育、立即浇注的瞬时孕育处理,并控制终硅量为2.95%~2.99%,可直接获得铁素体球墨铸铁,石墨球径仅为0.019~0.017mm,球化级别提高至3~2级,铁素体量多达88.4%~94.7%,力学性能完全达到国家标准。     

Iron-silica interaction at extreme conditions and the electrically conducting layer at the base of Earth's mantle

The boundary between the Earth's metallic core and its silicate mantle is characterized by strong lateral heterogeneity and sharp changes in density, seismic wave velocities, electrical conductivity and chemical composition. To investigate the composition and properties of the lowermost mantle, an understanding of the chemical reactions that take place between liquid iron and the complex Mg-Fe-Si-Al-oxides of the Earth's lower mantle is first required. Here we present a study of the interaction between iron and silica (SiO2) in electrically and laser-heated diamond anvil cells. In a multianvil apparatus at pressures up to 140 GPa and temperatures over 3,800 K we simulate conditions down to the core-mantle boundary. At high temperature and pressures below 40 GPa, iron and silica react to form iron oxide and an iron-silicon alloy, with up to 5 wt% silicon. At pressures of 85-140 GPa, however, iron and SiO2 do not react and iron-silicon alloys dissociate into almost pure iron and a CsCl-structured (B2) FeSi compound. Our experiments suggest that a metallic silicon-rich B2 phase, produced at the core-mantle boundary (owing to reactions between iron and silicate), could accumulate at the boundary between the mantle and core and explain the anomalously high electrical conductivity of this region.     

Melt Quality Evaluation of Ductile Iron by Pattern Recognition of Thermal Analysis Cooling Curves

The melt quality of ductile iron can be related to the melt's thermal analysis cooling curve. The freezing zone of the thermal analysis cooling curve was found to indicate the melt quality of the ductile iron. A comprehensive difference parameter, Ω, of the thermal analysis cooling curves was found to be related to the properties of ductile iron melts such as composition, temperature, and graphite morphology. As Ω ap- proached O, the thermal analysis cooling curves were found to come together with all the properties indicat- ing melt quality about the same. A database of thermal analysis cooling curves related to the properties of the ductile iron melts was set up as a basis for a method to accurately evaluate the melt quality of ductile iron by pattern recognition of thermal analysis cooling curves. The quality of a ductile iron melt can then be immediately determined by comparing its thermal analysis cooling curve freezing zone shape to those in the database.