回顾灰口铸铁接种

Prof.S.C。证券交易所,Y.E.Mangulkar

助理教授,部门的机械工程、及补助费、奥兰加巴德,印度马哈拉施特拉邦
打开学生,机械工程部门,及补助费,奥兰加巴德,印度马哈拉施特拉邦

文摘

在发达国家,研究相关的灰口铸铁的切削加工性能和微观结构进行了早期,特别是在菌剂的效果。也有越来越需要和需求的碳化过程获得自由,薄片灰铸铁铸件。接种是一个完善的过程,不仅可以防止硬质合金的形成,而且还控制石墨片的尺寸和形状的灰口铸铁。本文综述的一些发展发生雷竞技苹果下载了灰口铸铁孕育剂和接种程序。还一些最近的菌剂已经被不同的研究人员使用各种程度的成功已经简要解释。

关键字

灰口铸铁共晶细胞,接种,成核。

介绍

接种是目前普遍应用的冶金处理由铸造厂改善商业合金的力学性能。铸铁接种的本质在于熔融金属的物理化学状态的变化。这是一个意味着控制的结构和性能的铸铁通过增加可用的成核网站数量的增长石墨片在韧性铁灰色熨斗或石墨结节。获得的变化是通过引入的铸铁石墨成核功率低,模具浇注前不久,少量的变质剂,也就是说,一种化合物能够增加活动星系核的数量。的主要标准用于评价接种影响微观结构的变化,铸铁的力学性能及其令人心寒的倾向。亚共晶铸铁的凝固成核和生长过程,发生在阶段。当熔体冷却凝固始于熔点温度奥氏体树突的成核和随后的经济增长。随着温度继续下降,剩余的液体变成了丰富的碳,直到达到共晶成分的共晶温度。充分融化继续冷却,当过冷austenite-graphite共晶转变的开始。从液体到固体的转换是通过在一系列离散成核位置被称为共晶细胞(核)和收益的增长这些细胞沿着球状结晶的道路。 The eutectic cells continue to grow until they have impinged on one another and solidification is essentially complete. The form and distribution of the graphite phase of the eutectic is determined by the composition, cooling rate, and degree of nucleation of the melt.[1] Inoculation is a mean of controlling the structure and properties of cast iron by minimizing undercooling and increasing the number of nucleation sites during solidification. This means to prevent the undercooling to temperatures below the metastable eutectic where carbidic structures are formed (Figure 1). The iron solidification mechanism is prone to form chilled iron structures when inoculation is inadequate. Chilled structures interfere with the machining, necessitate additional heat treatment operations, results in non-conformance with specifications and, in general, increase the total cost of production. [2]

二世。疫苗接种史

75年,铸铁行业生产的主要技术和方法的变化和理解其基本冶金。接种扮演重要的角色在不断进步的铸铁。寻找高强度铸铁是基于知识的减少碳和硅低水平为高强度发展至关重要。钢增加了圆顶电荷从战争爆发的时候,和令人困惑的“钢性铸铁”一词是对任何铸铁在超过15%的钢屑已经包含在费用。这个词仍然盛行了大约30 - 40年之前最终消失。在早期,可怜的控制冲天炉和铁分析导致许多失望,甚至在1930年代,许多铸造经理仍将不会容忍穹顶钢。流程开发生产铸铁具有特殊属性通过使用加热或冷却模具,震动摇晃铁或使用特殊的指控。尽管他们蓬勃发展,他们很快便消失了。所有这些过程实际上是德国人,但在美国和英国在1920年代早期接种开始出现,虽然没有所谓。[3]1920年代的初期,许多铸造人调查了钢包添加对铸铁的影响。 Some of this work was done in secret, some of it was published, and some of it formed the basis of a variety of patents. Silicon control was in the forefront of everyone's minds. Strong iron was dependant on obtaining the lowest possible silicon content consistent with a grey fracture and machineability of thin sections. Crosby at the Studebaker Foundry added graphite and ferrosilicon (1922-1923), Meehan added calcium silicide and magnesium silicide (1922), Smalley used ferrosilicon, calcium silicide, and zirconium silicon (1922-1924), and Moldenke added aluminum (1921). The objective of all these various additions to the ladle were to control the graphite size and shape in low carbon equivalent iron, to promote A-type flakes instead of fine under-cooled forms, to obtain freedom from chill in thin sections, to promote uniformity throughout different section sizes, and to improve machineability. These are exactly the same objectives for which inoculants are still used today. [3]

在1920年代,被视为一个扫气过程,提炼,和脱氧融化,没有理解为一种成核。铸铁的冶金凝固的是还不完全理解,和许多争论了石墨是否直接从熔化,凝固或是否总是主要凝固,渗碳体的分解产物。例如,米汉纳公司规范使用的硅化硅铁或钙添加在1928年首次出现在英国。没有提到这个词接种在1920年代,和治疗只是称为包添加。接种和各种历史上属于下一时期,和他们的发起者是未知的。包含75 - 80%硅铁硅成为了最常见的变质剂。钙和铝硅铁的控制已经远非令人满意的早期,这可能帮助钙硅化物的初步成功。直到1938年,Lorig金尼尔和巴洛认为,钙和铝硅铁中的重要元素,是留给McLure道森出版社(1957)和(1961)表明最佳内容。石墨本身是被证明是有价值的变质剂Norbury和摩根和Linsay了起来。由国际镍和镁方法开创了铈的方法Morrogh和威廉姆斯都宣布在一个历史性的AFS国会在1948年在费城。 Because both magnesium and cerium are carbide stabilizers and the manufacturing of ductile iron requires an inoculation step, so inoculation received another boost. Ferrosilicon rapidly became the almost universal product to be applied in ductile iron.In grey iron the 1940s was a time of considering the best methods of adding the existing selection of inoculants. It was soon proved that the most effective method was into the stream of metal entering the ladle, and a number of simple devices were invented to do this. [3] However, further modifications to inoculation theories were proposed, e.g. the solidification of undercooled graphite was finally proved to be just as much a product of solidification from the liquid during the eutectic reaction as are random flakes by Hurum in 1952. The most notable suggestion for a new inoculant was the use of barium in a silicon-manganese alloy base by Kessler in 1956. Commercial barium-containing inoculants were developed by the Vanadium Corporation and Baranov, and strontium ferrosilicon was prepared by BCIRA and Union Carbide after the work of Dawson and Clark and McCluhan. Cerium-bearing inoculants were proposed, and appeared from the Vanadium Corporation. Mixed inoculants giving good control over the very potent effects of graphite were introduced by Foseco. The problem of fading had been recognized very early on, and it was acknowledged that inoculated metal had to be poured in 10 minutes or less to avoid this. In the mid-1960s, the problem was tackled in a different way, and inoculation of the metal directly in the mould was attempted with no further problem in fading. The investigations of Dell and Crist, Trager and Kaune, Hall, Bakkerus and Gaertman, and Ryzhikov proved that the concept was viable by using a variety of inoculants either as fines, lumps, pellets, or tablets. Karsay used a different technique and inoculated in the spout of the ladle with a tube filled with inoculant. [3]

三世。LITRATURE调查

J.N.哈维出版社描述了铸铁接种的必要性和不同的接种技术的灰色和球墨铸铁。他还探讨了影响各种变质剂材料铸铁的显微组织。同时,案例研究基于接种方法的变化,和铸铁孕育剂的成绩。[3]N.T. Skjegstad Et.Al Described Important Conditions In The Production Of Cast Iron Which Call For The Addition Of An Inoculant To Ensure The Reliable Production Of Sound, Strong, And Machinable Castings. The Principal Differences Between Inoculated And Un-Inoculated Cast Irons Are Described, And These Differences Are Exemplified By Characteristic Microstructures And Mechanical Properties. Also, Some Practical Considerations Related To Various Methods Of Inoculant Addition To Liquid Iron Are Explained. [4] J.O. Choi Et.Al Investigated That Effect Of Rare Earth Metal(RE) On Microstructural Features In Thin Wall Ductile Iron Castings, Including The Thickness Of Ferrite Layer Around Graphite Ferrite, Graphite Nodule Size, And Graphite Nodule Count, Depend On The Amount Of Rare Earth Elements And Sample Thickness. The Addition Of RE Leads To A Decrease In The Amount Of Chill Formation, A Higher Graphite Nodule Count And Size As Compared To Those In The Specimens Without RE. He Suggested That The Role Of RE Varies With Sample Thickness. Irrespective Of The Addition Of RE, Suggesting That The Effect Of Rare Earth In Reduces Chill Formation In Very Thin Sections. Due To The RE Addition Nodularity Of Graphite Nodules Improved, A Lower Tensile And Yield Strength Reduced In Specimens Without RE. [5]

S.O.奥尔森出版社描述重要的铸铁的生产条件和微观结构特征和力学性能例证接种和Un-Inoculated铁之间的区别。接种的主要机制和石墨成核在灰色和韧性铁。研究结果是基于先进的电子显微镜研究微粒作为石墨异相成核的网站。影响小的合金元素,如钙、Ba、Sr、解释以及重要作用石墨氧和硫的成核过程。[6]Iulian Riposan等。研究了强脱氧元素的影响,如铝、锆、钛,在灰色的熨斗,相同的0.03 Wt %之外。铝、锆有可见的有利影响,通过降低程度的共晶过冷,令人心寒的趋势,过冷石墨,和免费的碳化物数量,未接种,接种熨斗。Ti似乎是有益的,只在Un-Inoculated铁石墨化作用,但较低的相对力量与铝、锆相比。出行,复杂(Mn, X)年代化合物有核基于前面氧化形成很小的网站作为主要的石墨片的成核点的具体分布,钛、锆。[7]V。Popovski和研究影响Ledeburitic渗碳体铸件的不可接受的质量和效果基于钡复合菌剂接种的由两个不同的供应商。研究表明,添加变质剂的量对Ledeburitic渗碳体的形成产生影响,削弱了机械切削加工性能。 Inoculants Help To Balance The Hardness On The Castings. The Measurements Showed That The Difference In Hardness Of The Castings At Different Wall Thicknesses Is Smaller In Cases, Where Inoculants With Less Barium Were Used And They Also Were Alloyed With Calcium And Also Contained No Aluminium. Occurance Of Ledeburitic Cementite Is Undesired Because Such Castings Cannot Be Machined With Removing Material. Thin Walled Castings Are Especially Sensitive To Precipitation Of Cementite. The Observed Casting Had The Wall Thickness Of 6 Mm To 7 Mm On The Base And 25 Mm In The Center. Hardness Measurements And Microscopic Test Showed That The Most Suitable Inoculant For The Chosen Casting Was The One That Besided Iron And Silicon Contains Also 2 % To 2.5 % Of Barium And 2 % To 2.7 % Of Calcium. [8]

四、接种方法

答:预处理

预处理用来描述一个特定的变质剂的清洁,脱渣炉融化表面烧结前处理过程。这个事件是规范化的成核势融化。变质剂可能高纯石墨,接种年级硅铁或碳化硅颗粒。在每种情况下,除了必须的大小将很快溶解。碳化硅的尤其如此,因为这除了溶解而不是融化。通常,添加0.1%或1公斤每公吨(2磅每吨)能充分提高核的形成。[9]

b . Pre-inoculation

在这个阶段,除了接种年级硅铁是由要么包铁的流填充治疗,或作为合金的一部分“包”治疗包。变质剂可能覆盖材料的一部分在一个三明治或中间包治疗。结合镁合金和硅铁孕育剂有助于削弱Mg的硬质合金促进作用和调整硅含量的铁根据年级的针对性和铸件断面尺寸。像其他接种步骤,变质剂的主要功能是添加成核网站促进石墨粒子的增长与碳化物的增长。[9]

c .钢包接种

这是典型的接种方法,变质剂添加在攻丝或浇注,例如镁后治疗。根据大量的铁、菌剂与晶粒尺寸之间的0.6毫米和6毫米大多用于这种类型的接种。必须确保接种体不放在包的底部但尽可能稳定铁流。钢包接种通常被称为“后接种”可能是接种过程的最重要的一步。因为暴力的Mg反应在球化处理,生成的核的一个重要部分步骤1和2可以在表面熔渣覆盖变得越来越大铁融化。镁治疗融化也倾向于过冷。因此有必要恢复的成核势铁。[9]

d .后期接种

晚接种接种系列中的最有效的步骤。众所周知,镁治疗过程的影响,以及添加菌剂随着时间慢慢变淡。通过移动接种事件尽可能晚的浇注工艺,衰落的影响最小化。通常,一个小的后期变质剂可以换一个更大的在前面的步骤中。在某些情况下,晚些时候接种可能是可以避免的。最后一个步骤可以作为安全程序而不是绝对必需的。在某些情况下,接种后期补偿低于最优费用组成和/或融化的过程和/或球状化处理过程。例如,尽管后期接种不完全抵消有害元素,如铬的影响,V, Mo,某人,V Ti可以减少不利影响的增加根瘤数和减少偏析的程度。[9]

控制接种实践很重要,必须使用正确的技术获得令人满意的和一致的结果。菌剂必须与铁水获得混合均匀和完整的解决方案。获得了良好的混合通过增加攻流从钢包炉或转移到钢包。的做法将变质剂在钢包底部开始填补不推荐。[2]影响因素的选择接种方法[7]:1。时间从灌装桶倒过去的铸造,俗称消退时间。2。金属温度。3所示。添加变质剂的能力在一个特定的点。 4. Suitability of the casting system to late stream inoculation. Inoculants are generally added to cast irons at one or more of four stages during the casting procedure as shown in figure 2 [2],[7]: 1. To the transfer ladle. 2. To the pouring ladle. 3. To the stream of metal as it enters the mould. 4. Using an insert placed inside the mould runner system

使用插入由压制或铸造接种菌很少用作接种的主要来源。不同大小和构成平板电脑是可用的和被证明是特别有价值的消失时间长时,作为二次接种,只有当后期金属流处理是不可能的。人为错误的可能性没有平板电脑添加到一个模具需要高度的铸造检验,通常在一些情况下,平板电脑作为唯一的变质剂。[7]如果无法避免,接种后长时间持有接种可能超过了一个额外的,小的。另外,接种可能被认为是某种形式的晚。金属流后期接种几乎消除了褪色。接种方法金属后离开了钢包和进入模具或模具内部,称为接种。后期接种,正确应用,给的最大效应获得从一个接种,从而产生更高水平的接种,因此更低的倾向比包单独接种。后期接种时应使用不可能达到和维持足够的钢包接种。后期接种需要分开,广泛试验为每个铸件和建立一个合适的流程,建立之时,这一过程必须严格遵守,以避免困难。 Late inoculation may be used in addition to ladle inoculation in order to obtain an extra effect, but preliminary trials must first be made to ensure that it will be successful. [2]

V。有效的接种的原则

1。有效接种基数较低铁冷却值应该维持治疗前和接种。2。除了正确的数量、类型和大小的菌剂的金属处理和铸件断面尺寸/冷却速率。

3所示。过度罚款接种的变质剂可能会导致糟糕的结果,因为他们已经氧化了。4所示。在接种可能导致增加金属的收缩倾向。5。高温增加衰落趋势和低温促进碳化物形成的护理时间添加变质剂和倒应该正确的温度铸造金属部分。6。合适的混合接种体的金属会导致均匀和细微观结构。7所示。最小化后的金属氧化菌剂已被添加。 8. After completion of inoculation process the metal holding time should be as short as possible. [10]

VI.INOCULANTS

变质剂是一种材料添加到铁水铸造之前提供一个合适的成核阶段石墨在随后的冷却。变质剂的目的是协助提供足够的沉淀的碳石墨的成核点而不是碳化铁(渗碳体)。传统上,各种基于石墨,硅铁或硅化钙。今天最流行的变质剂含有少量的元素如铝、硅铁Ba、钙、锰、Bi、Sr、锆。[2]FeSi作为一个纯物质没有接种效果。结合活性元素如铝、钙、Ba、锰、锆、Sr Bi添加到FeSi何时接种。在这些;英航,Zr、Sr Bi比铝更强大的活跃元素和基于Ca在FeSi的菌剂。这将导致更低的利率。[5]接种体的大小通常是½英寸(13毫米)最大。 Since fines do not inoculate effectively, a minimum size limit of 1/6 inches (1.5 mm) is advisable. The inoculant should be stored in closed containers. Its effectiveness deteriorates with time when exposed to open air and moisture. [8] The prime effects of a few inoculants are listed in the table 1.

七世。衰落的影响

一)主要衰落的影响

后立即接种的影响在一个最大的变质剂。变质剂的速度消退,这取决于变质剂的组成和铁的添加,可以非常迅速和接种的效果可能会丢失后的最初几分钟。衰落的主要影响是[2]:1)导致更大的过冷期间发生共晶凝固,导致伟大的趋势在灰色和球铁冷却,尤其是在薄片。2)减少共晶细胞生长在片状石墨铁导致不均匀的粒度分布的石墨在铸造和机械性能的减少。

3)减少形成的结节在球墨铸铁和导致恶化他们的形状。如果足够严重,恶化的形状会影响铸件的机械性能。

B)关于衰落的事实

有一些行之有效的事实有关衰落的现实意义[2]:1)所有菌剂在一段时间后将消失。2)没有时间期间接种后不褪色。获得最大的效果,金属后应尽快把添加变质剂。3)一些菌剂比其他人更慢慢消退。4)接种的影响根据不同变质剂组成。它是可取的,铸造厂应进行测试,以确定最合适的变质剂是为他们的特定的目的。

VIII.CONCLUSION

从以上研究可以看出各种比例的变化和改变基材成分我们可以改善贱金属的性质。因此得出结论,接种是最好的一个合适的过程来获得所需的贱金属的力学性能和微观结构变化的百分比一样,各种大小的变化,贱金属的温度时间添加菌剂和贱金属成分的变化。

确认

作者是负债向董事和机械工程部门负责人Deogiri工程和管理学院的研究,奥兰加巴德。

引用

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