灰口铸铁抗拉强度值的Weibull统计分析

制备了HT200和HT150两种牌号灰口铸铁抗拉试样并进行了拉伸试验.通过对强度值进行Weibull统计分析以及对试样的石墨形态的观察分析,认为灰口铸铁的脆性表现主要在于片状石墨的切割作用;片状石墨的不均匀分布是造成灰口铸铁抗拉强度值分散的主要原因.     

铸铁在铝液中侵蚀机理的研究

研究了金相组织对铸铁耐铝液侵蚀性能的影响;利用Ｘ射线衍射分析和金相分析探索了铸铁在铝液中的侵蚀机理;黑色保护层的表成导致铸铁耐铝液侵蚀性能增强,石墨形态和珠光体基体影响铸铁耐铝液侵蚀速率;结果表明,片状石墨和细片状珠光体数量越多,耐铝液侵蚀性能越强。     

复合石墨组织铸铁抗铝液侵蚀的机理及应用

石墨与铝合金熔液之间润湿性差，在有限铝液高度时，铝液对灰铸铁石墨片之间的铁组织的侵蚀也可忽略。可利用具有片状组织的灰铸铁抵抗铝液侵蚀；将铸件内层设计为球墨铸铁以利用其高温强度性能；该复合层铸铁件可用铸造方法一次获得。试验结果证实了复合石墨铸铁用于处理铝合金熔液的装置是可靠的。     

珠光体灰口铸铁静载与疲劳断口形貌扫描电镜观察及其断裂机理初步研究

本文对珠光体灰口铸铁的静载拉伸、冲击试样断口和旋转弯曲疲劳试样断口的扫描电镜观察结果进行了对比研究,认为断口的微观形貌取决于加载方式。据此提出:珠光体灰口铸铁静载断裂与疲劳断裂可从断口上的石墨暴露率、片状石墨及珠光体组织断裂特征三个方面来判定。在断口微观形貌观察的基础上,对片状石墨和珠光体组织的断裂机理进行了初步探讨。     

铸铁在铝液中浸蚀机理的探讨

研究了铸铁在铝液中的浸蚀机理，发现铸铁在铝液中是通过铝原子的扩散，形成铁铝合金层后剥落和溶解造成浸蚀的。铸铁中的片状石墨对铝原子的扩散有很好的阻碍作用，并在铸铁表面上形成由石墨碳、Al_4C_3和铁铝化合物组成的保护层，进一步提高铸铁在铝液中的耐浸蚀性能。获得均匀分布的细小A型石墨，消除碳化物有利于提高耐浸蚀性能。     

铸铁模具产生裂纹的原因及解决办法

针对铸铝用铸铁模具在使用过程中产生裂纹问题,经分析表明:产生裂纹的原因是原铝锭铸铁型是由以珠光体为基的普通灰口铸铁制造,在浇注720℃铝液时,由于热胀冷缩将产生较大的应力;珠光体将逐渐分解形成铁素体;而灰铸铁中片状石墨又易产生应力集中,加剧了裂纹的扩展。在上述热应力、组织应力的共同作用下,导致裂纹产生,使铸铁模具报废。采用以铁素体为基的蠕墨铸铁可解决此问题。     

石墨形态对铸铁在铝液中耐腐蚀性的影响

运用微观分析和失重法研究了球墨铸铁和耐铝液腐蚀铸铁在铝液中的耐腐蚀机理.试验结果表明,铸铁在铝液中的腐蚀是由于铝原子在铸铁基体中扩散并形成铁铝金属间化合物,进而剥落溶解,造成铸铁的腐蚀.其中,石墨形态是铸铁腐蚀性能优劣的关键因素,交织成网状结构的片状石墨对铝原子的扩散有最强的阻碍作用,在铸铁表面形成的石墨、碳化物和Fe-Al金属间化合物界面提高了铸铁的耐腐蚀性能.     

灰口铸铁的热处理

<正>灰口铸铁中的石墨是片状的,对基体的割裂作用大。热处理只能改变基体组织,不能改变石墨的形状和分布。强化基体的热处理对灰口铸铁效果不大。所以灰口铸铁一般不进行这类热处理。球墨铸铁的石墨是球状的,对基体的割裂作用小,基体的强度利用率可达70%~90%,所以球墨铸铁可以进行这类热处理。总之,凡能强化基体的各种热处理方法,对球墨铸铁都非常有效。常对球墨铸铁使用的热处理方法有以下几     

蠕墨铸铁中石墨形状的研究

前言近十几年来,国内外大力开展了对蠕墨铸铁的研究工作。由于它的机械性能、物理性能均介于友口铸铁与球墨铸铁之间,并有着接近灰口铸铁的良好铸造性能,所以,这种材料已在机械制造领域占据了一隅,正在发展成为一种具有独特性能的机械工程材料。以光学显微镜对蠕墨铸铁进行观察,常见的石墨形态有球状石墨、球片状石墨、开花状石墨、蠕虫状石墨和点状石墨等五种形态.近年来发展的一种根据光学显微镜下观察到的石     

同步送粉铸铁表面大功率CO2激光熔覆工艺研究

采用２０ＫＷＣＯ２激光器及同步送粉熔覆技术,在球墨铸铁和灰口铸铁表面熔覆镍基和钴基合金,研究铸铁组织,合金粉末体系和工艺参数对熔覆层气孔和裂纹的影响。结果表明：熔覆支气孔的形成与铸铁组织,石墨形态有关,片状石墨灰口铸铁易产生气孔,而裂纹主要取决于所使用的合金体系,其中钴基司太立合金具有良好的抗裂性能,通过优化激光熔覆工艺参数,可以避免熔覆层裂纹和气孔的形成。     

灰铸铁中石墨形态分级及其特点

文章就美国标准ASTMA-247与GB7216-1987对铸铁的石墨形态分级作了详细介绍。美国材料与实验学会ASTMA-247中将铸铁中可能出现的石墨形态分成7类,其中对灰铸铁的石墨形状分为5种,从A型到E型,而GB7216—1987把灰铸铁的石墨形状分为6种,即A型到F型。同时将石墨片长又分成8级。     

表层石墨球化的灰铸铁件外表层片状石墨的防止

利用含有稀土的涂料实现了表层石墨球化的灰铸铁件,其组织形态由外到内依次为球化区、过渡区和灰铸铁本体。生产中发现,在某些条件下,已经实现了表层石墨球化的灰铸铁件的外表层又出现片状石墨。为防止这种现象发生,进行了研究。     

稀土蠕化剂对蠕墨铸铁石墨形态和性能的影响

对以云南地方生铁为主要炉料的铁液,搭配使用稀土硅铁合金和稀土镁合金作为蠕化剂,研究了稀土蠕化剂加入量对蠕墨铸铁石墨形态和性能的影响。研究结果表明,随着稀土蠕化剂加入量的增加,铁液中稀土残留量逐渐增加,石墨形态从片状逐渐向球状过渡,抗拉强度和硬度逐渐上升。实践证明,通过合适的蠕化处理工艺,云南地方生铁铁液可以获得组织和性能较为理想的蠕墨铸铁。     

Colour Metallography of Cast Iron

Chapter 3 Spheroidal Graphite Cast Iron（I） Spheroidal Graphite Cast Iron, SG iron in short, refers to the cast iron in which graphite precipitates as spheroidal shape during solidification of liquid iron. The graphite in common commercial cast iron can only be changed from flake to spheroidal shape by spheroidising treatment. Since spheroidal graphite reduces the cutting effect of stress concentration, the metal matrix strength of SG iron can be applied around 70%-90%, thus the mechanical property of SG iron is significantly superior to other cast irons;even the tensile strength of SG iron is higher than that carbon steel.     

铸铁的电化学腐蚀机理

在深入分析已有文献试验数据和用户使用经验的基础上，根据腐蚀的电化学原理，总结出铸铁中的石墨形态和基本组织对耐蚀性的不同影响取决地铸铁在腐蚀介质中所处的状态。铸铁在介质中处于钝化态时，石墨促进钝化，细片状石墨的珠光体灰铸铁耐蚀性最好。铸铁在介质中处于活化状态时，石墨加速铸铁的腐蚀，铁素体球墨铸铁耐蚀性优于其它组织的普通铸铁。     

高强度D型石墨铸铁的研究进展

综述了灰铸铁中产生D型石墨的原因，D型石墨对灰铸铁性能的影响以及D型石墨灰铸铁的应用。国内外的研究表明：深过冷，在灰铸铁中加入提高过冷度的合金元素（钛，铝，锑，碲，稀土元素等）或者二者的结合都会促进生成D型石墨；D型石墨灰铸铁具有较高的强度，较好的抗氧化性，抗生长性，抗热疲劳性和耐磨性；D型石墨灰铸铁已经广泛用于生产玻璃模具，压缩机缸体，压缩机曲轴等铸件。笔者还介绍了采用钒钛生铁生产的D型石墨合金铸铁凸轮轴的性能特点及其应用情况。     

High Temperature Oxidation Behavior of Flake and Spheroidal Graphite Cast Irons

Flake and spheroidal graphite cast irons with similar composition were subjected to high temperature oxidation to investigate graphite morphology and distribution effects on the oxidation behavior. High temperature oxidation tests were conducted between 400 and 750 °C in air. For comparison low carbon steel was also tested.Graphite morphology obviously affected high-temperature oxidation resistance. The flake graphite cast iron exhibited the worst high-temperature oxidation resistance compared with spheroidal graphite cast iron. Since graphite flakes provide suitable sites for the iron oxide growth and are almost interconnected, the iron oxide grows faster and penetrates along the graphite flakes boundaries resulting in the subsurface oxidation. Due to the severe subsurface oxidation flake graphite cast iron parabolic rate constants are five times higher than that of the spheroidal graphite cast iron. However, spheroidal graphite cast iron parabolic rate constants and oxide layer thickness are similar to those of the low carbon steel. Therefore, graphite flakes have negative effect on the cast iron high temperature oxidation resistance.     

薄壁灰铸铁件中的蠕虫状石墨

研究３ｍｍ的薄壁灰铸件的石墨形态，特别是蠕虫状石墨的形态。这种蠕墨呈单片或空间相互联结的多个蠕墨片；尺寸非常细小，其长度和厚度为蠕墨铸铁件中的蠕墨的１／３－１／１０。     

Calculating the effective thermal conductivity of gray cast iron by using an interconnected graphite model

A new theoretical model of gray cast iron taking into account a locally interconnected structure of flake graphite was designed, and the corresponding effective thermal conductivity was calculated using the thermal resistance network method. The calculated results are obviously higher than that of the effective medium approximation assuming that graphite is distributed in isolation. It is suggested that the interconnected structure significantly enhances the overall thermal conductivity. Moreover, it is shown that high anisotropy of graphite thermal conductivity, high volume fraction of graphite, and small aspect ratio of flake graphite will cause the connectivity effects of graphite to more obviously improve the overall thermal conductivity. Higher graphite volume fraction, lower aspect ratio and higher matrix thermal conductivity are beneficial to obtain a high thermal conductivity gray cast iron. This work can provide guidance and reference for the development of high thermal conductivity gray cast iron and the design of high thermal conductivity composites with similar locally interconnected structures.     

Production of iron castings with altered graphite morphology by a modified Inmold process

A new melt combination process which can control the graphite morphology from spheroidal, compacted-vermicular to flake in cast iron has been developed by a modified Inmold process. Two reaction chambers were prepared in one sand mould. One reaction chamber was for spheroidizing and the other was for inoculating. After being poured into the sprue, the molten iron, of a given chemical composition, was separated in the runner and passed through each reaction chamber. The separated metal streams then collided with each other and filled the cavity. As a result, a new iron, with one side having the properties of spheroidal graphite cast iron and the other the properties of flake graphite cast iron, was produced. The graphite structure has usually been controlled using filters, dams or chillers.