锰铸铁的结晶过程与组织特点

研究了锰量在小于2．5％范围内变化时，灰铸铁的结晶特性与组织变化。试验表明：锰显著增大铸铁共晶过冷度，细化共晶团，促进D、E型石 墨的形成，有较强的白品倾向，可有效细化基体组织，促进硬化相网孔组织的形成。试验发现，反石墨化的正偏析元素可促进一种新型的“逆B型”石墨出现，其分布特征完全区别于现已命名的A型－F型石墨。     

铁神一号净化剂对灰铸铁组织和力学性能的影响

利用中频感应电炉熔炼灰铸铁铁液，水玻璃砂造型，浇注铸造阶梯试样、φ30mm试棒以及热分析试样，研究了净化剂对其结晶过冷度、组织和力学性能的影响。试验结果表明，单独加入净化剂0．6％可以增加过冷倾向，细化石墨，降低断面敏感性；可以提高灰铸铁的抗拉强度和冶金质量指标；同时加入净化剂0．6％和硅钡孕育剂0．7％对灰铸铁进行复合孕育，明显增加共晶团数量至441个/cm^2，可以获得细小A型石墨，显著提高灰铸铁的力学性能σb至282MPa。     

聚丁烯(PB)/石墨复合材料结晶和力学性能的研究

本文利用钛酸酯偶联剂NDZ-101处理石墨,采用熔融法制备了聚丁烯(PB)/石墨复合材料.利用DSC、XRD等研究了材料晶型、结晶度随结晶时间的变化,同时研究了复合材料结晶性能对其力学性能的影响.研究表明,随着结晶时间的增加,PB/石墨复合材料的晶型由Ⅱ转变为Ⅰ,石墨的加入加速了晶型的转变;随着石墨含量的增加,PB/石墨复合材料的拉伸强度和抗弯强度增加,而冲击强度降低;当PB/石墨复合材料中石墨含量为15%(质量分数)时,随着晶型的转变和结晶时间的增加(从2 h到96 h),复合材料的拉伸强度从17.34 MPa增加到26.59 MPa,弯曲强度也增加了20%,而冲击强度却降低了大约50%.     

凿岩机缸套的铸造工艺

YN27型内燃凿岩机缸套为风冷式缸套，其本体结构特点是：散热片大而密集，片间距仅5mm。铸件材质要求HT30O，化学成分（％）为：3．2～3．4C，1．8～2．2Si．0．7～0．9Mn，＜～1．0CU。石墨为A型十B型，允许有5％以下的D、E型．石墨长度为4～6级，基体为珠光体，铁素体不超过5％，不允许有大块状或网状磷共晶。原铸造工艺采用卧浇，侧冒口补缩，不仅工艺出品率低，且铸件局部热节区（见图中的A区）缩孔、缩松等综合废品率高过30％。考虑到缸套本体结构特点及HT30O合金的凝固特性，补缩是工艺的关键，缸套为复杂小件，补缩的实质是…     

铜合金石墨型铸造

一、石墨型铸造的优点石墨型铸造是硬型铸造的一种。同现在常用的铸型材料相比,有下列几个特点:1．石墨具有较高的导热系数、导温系数和热容量(见表1)。因而铸造合金在石墨型中结晶速度快,铸件得到了快速凝固,致使合金组织变细,提高了合金的致密性和机械性能;     

玻璃模具用低铬D型石墨灰铸铁的研究

对低铬D型石墨灰铸铁的成分、组织和性能进行了研究。试验结果表明：选择适宜的基本元素（3．4％C、2．2％Si、0．5％Mn、＜0．15％S、＜0．12％P）,控制Cr和Cu的含量分别为0．75％和0．7％,用湿砂型和下型安放大块冷铁的铸造工艺控制冷却速度,经热处理后,可获得具有良好石墨形态的D型石墨灰铸铁,其抗氧和热疲劳性能分别是普通灰铸铁的4．1倍和4．2倍,适于制作玻璃模具。     

再探蠕虫状石墨的形成机理

通过对不同冷速下结晶蠕铁的液淬试样进行分析观测，对蠕墨铸铁的一次结晶及蠕墨的形成机理进行了一些探讨，并进一步阐述了石墨中倾斜孪晶的作用。     

蠕虫状石墨的生长特点

用单向凝固技术和扫描电镜研究经变质处理的Fe-C-Si共晶合金中蠕虫状石墨的形貌特征、形成过程及生长特点。试验表明,蠕虫状石墨主生长方向和结晶取向是不断变化的,从而构成了不同的形态,     

含Pb、As、Sn D型石墨铸铁抗氧化性能的研究

利用含Pb、As、Sn地方生铁制取D型石墨铸铁并测定了这种铸铁的抗氧化性能。结果表明：这种含Pb、As、Sn D型石墨铸铁的抗氧化性能明显优于A型石墨铸铁。在600℃时，其抗氧化性能比A型石墨铸铁提高了56％－64％；在900℃时，其抗氧化性能也比A型石墨铸铁提高了约5％－27％。     

单体铸造活塞环中 E 型石墨浅析

内燃机单体铸造活塞环金相检验标准中规定:石墨应为适当大小的 E 型、A 型或 B 型,分散度较大,分布均匀。E 型石墨在工作表面层内,其数量不超过视场面积的10％。E 型石墨我们通常称为“过冷石墨”或“枝晶石墨”。E 型石墨是有规则排列(有方向性)的点状和短、小片状石墨。众所周知,单体活塞环属于特小、薄铸件,其成     

灰口铸铁中石墨分布的优化

为了获得优秀的灰口铸铁性能,控制石墨的形态和分布是关键,而石墨的形成取决于凝固过程中经过共晶区间时的冷却条件,适当的金属液处理和有效的成分控制,能获得分散的、均匀分布的A型石墨。     

Characteristics of the fracture surface of gray magnesium cast irons after dynamic fracture

Conclusions Modification of gray test iron with as much as 0.08% Mg leads to globularization of graphite and greatly changes the average rate of fracture. The fracture of the pearlitic matrix is brittle in character. The fracture of the pearlitic matrix is brittle in character. Thus, the discrete pattern of crack propagation observed is due mainly to the presence of graphite inclusions, which are areas of scattering of the elastic energy of the crack — relaxation areas. Comparison of the electron fractographs of cast and heat-treated samples (alloy with 0.08% Mg) revealed new elements of brittle fracture in the latter. Crack propagation in the ferritic cast iron is a ccompanied by intensive twinning (Fig. 3g, positive replica). It should be noted that ferritizing annealing has a negligible effect on the average rate of crack propagation (350 m/sec).The presence of ferrite in castings of alloys modified with 0.15 and 0.23% Mg has a negligible effect on the fracture, since the ferrite contains silicon and is therefore not a ductile phase. Comparison of the type of fracture leads to the conclusion that fracture can be regarded as brittle for all the cast irons tested. The change in the fine structure of the fracture surface with increasing magnesium concentrations first manifest in increasing signs of brittle fracture (up to 0.08% Mg) and then in weakening of these signs, is due to the change in the rate of crack propagation, which in turn depends on the shape and distribution of graphite, depending on the structural condition of the cast iron.Institute of Problems of Machine Construction, Academy of Sciences of the Ukrainian SSR. V. I. Lenin Kharkov Polytechnic Institute. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 8, pp. 26–28, August, 1979.     

卧式离心铸造汽缸套"黑斑"形成机理及预防措施

卧式离心铸造合金铸铁汽缸套"黑斑"是一种由合金成分和生产工艺等因素而造成的"夹层"石墨漂浮、比重偏析的综合缺陷.主要预防措施是强化冷却和将锰含量提高到2%.     

C、Si、Mn、Cu对中锰球墨铸铁组织和性能的影响

应用湿砂铸型浇注中锰球墨铸铁,采用正交设计研究了C、Si、Mn、Cu对中锰球墨铸铁组织和力学性能的影响。结果表明,中锰球墨铸铁的铸态组织为奥氏体＋碳化物＋球状石墨,扫描照片中可见有大量细小均匀的韧窝。中碳、高硅、中锰和低铜有利于提高中锰球墨铸铁的硬度;低碳、高硅、中锰和中铜有利于提高其冲击韧度;低碳、中硅、低锰和低铜有利于提高其耐磨性。新开发的中锰球墨铸铁的硬度、冲击韧度和耐磨性远高于目前生产排沙潜水泵过流部件中所使用材料的各项性能,使用寿命是其2倍左右。     

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。     

一种铸铁用复合过滤器的开发

所开发的用于铸铁的双层过滤器(复合过滤器)同时具有无衰退的孕育功能和净化功能.该复合过滤器由涂挂孕育剂的第一层过滤器和比第一层过滤器更细的第二层过滤器所组成.使用复合过滤器进行了灰铸铁和球墨铸铁的浇注试验,在灰铸铁中,得到了A型石墨,提高了抗拉强度.在球墨铸铁中,石墨大小、形状变得均匀,改善了伸长率.伴随在孕育过程产生的夹杂物可以被第二层过滤器所截获.结果表明这一复合过滤器具有良好的孕育和过滤效果.     

Effect of nodularity on mechanical properties and fracture of ferritic spheroidal graphite iron

Ferritic spheroidal graphite irons with nodularity from 72% to 96% were prepared. The relationship between the nodularity and the mechanical properties of the ferritic spheroidal graphite iron was investigated. The effect of nodularity on the mechanical properties and tensile fracture of the cast iron were studied. Results showed that the tensile strength Rm, yield strength R_(p0.2), elongation to failure A_5, and impact energy KV_2 of the cast iron had a good linear relationship with its nodularity. Nodularity and annealing treatment would obviously affect the fracture characteristics of ferritic spheroidal graphite iron. The annealed ferritic spheroidal graphite iron with 93% nodularity showed a completely ductile rupture. With the decrease of nodularity from 93% to 72%, the cleavage fracture area ratio increased gradually from 0% to 8.3%. Compared with as-cast ferritic spheroidal graphite iron, annealing treatment reduced the cleavage fracture area of the ferritic spheroidal graphite iron.     

钛在灰铸铁中行为的研究

研究了钛（Ti）对灰铸铁组织和性能的影响。结果表明,钛有促进D型石墨形成的作用,不同含量的钛对D型石墨形成的影响程度不同,当钛含量为0．36％时,铸铁具有较好的力学性能。     

MICRODISTRIBUTION OF NODULIZER IN VARIOUS PHASES OF CAST IRON

应用有机电解液低温电解及放射性测量方法,测定了普通铸铁及高纯Fe-C-Si合金中的合金化Ce量及石墨中的Ce量,石墨中的Ce量大都略高于或相近于基体中的Ce量,在Ce含量相同的情况下,铸铁中的合金化Ce量比钢中多。 涂层法自射线照相结果表明:Ce在片状石墨中呈均匀分布,而在球状石墨中的分布却是多样的。开花状石墨中的Ce多于片状石墨及球状石墨中的Ce.球状石墨周围的铁素体及珠光体是贫Ce.远离球状石墨的珠光体及莱氏体是富Ce.初生奥氏体枝晶转变形成的珠光体和蜂窝状莱氏体都含有较少的Ce,而板状渗碳体型莱氏体含Ce较多.Ce明显富集于共晶时最后凝固的区域。球状石墨的形成主要取决于原铁水中的反球化剂(硫)含量,它的影响比球化剂的残留量或合金化量的作用更大。     

Benefits of Residual Aluminum in Ductile Iron

Two main chemistry systems of micro-inclusions can be identified in ductile iron: Ca-S-X and Mg-Si-O-X with the majority of the inclusions regardless of treatment type and location being of the second type, silicates. Laboratory investigations have shown that simple silicates were present in the matrix, while more complex silicates were present in conjunction with graphite, probably acting as graphite nucleation sites. In these more complex silicates, elevated levels of Al, Ca, Ce and La were typical. Comparing micro-particles embedded in iron matrix and graphite nodules of iron treated with pure Mg-metal and iron treated with MgFeSi alloy showed a higher amount of complex silicates with elevated Al-levels in the iron treated with MgFeSi. Further laboratory investigation was undertaken to explore which source of Al and which range of residual Al would have a favorable impact on the graphite nucleation in ductile iron. The work showed that a residual aluminum of 0.005 to 0.020 wt.% appears to be beneficial for improving ductile iron solidification characteristics without the incidence of pinholes. Greatest benefits were achieved when introducing the Al into the iron via an inoculant late during processing or via a pre-conditioner to the base iron. Al added via the MgFeSi provided less benefit. Some case studies illustrating the effect of Al in ductile iron are also presented, as Al-containing pre-conditioner or/and Al-bearing, FeSi inoculant application.