关 键 词：

型号 冲压 模具设计 工艺 分析 冲孔 复合 CAD

资源描述：

某型号角架冲压模具设计及工艺分析-落料冲孔复合模含8张CAD图,型号,冲压,模具设计,工艺,分析,冲孔,复合,CAD

内容简介：

设 计（论 文）任务书设计(论文)题目： 某型号角架冲压工艺分析及冲压模具设计 学生姓名： 学 院： 专 业： 班 级： 学 号： 指导教师： 下发任务书日期： 20XX年12月20日任 务 书1本毕业设计（论文）课题应达到的目的：该零件的生产涉及多道冲压工艺，本课题不仅要研究其冲压成形的工艺方案，完成设计冲裁工序模具，还要充分考虑到各工序之间的衔接。 通过对本课题的研究，旨在让学生综合应用所学的专业理论和设计方法，参与生产实践，以达到对冲压件的成形特性、冲压成形质量的保证有深刻的认识和理解，从而制定合理的冲压工艺方案并完成模具的设计。2本毕业设计（论文）课题任务的内容和要求（包括原始数据、技术要求、工作要求等）：课题的任务是设计一副冲裁模具，具体设计要求如下： 1）根据给出的零件，完成零件的测绘并完成零件图的设计，在对零件进行冲压工艺性分析后，各参数应合理地满足冲压工艺要求，零件材料自定； 2）根据零件图要求完成一副冲裁模具（应该包含两个或两个以上的工序），结构形式自己确定； 3）自定生产批量，重点要注意下料展开尺寸的计算准确性，凸、凹模的间隙值的选择、在选择设备时要注意设备的工作行程、工作台面尺寸与模具的关系，在考虑排料方式时，应该最大限度的提高材料的利用率； 4）模具设计时要严格按照国家标准选用公差、技术参数和模架；要求用CAD完成图纸的设计； 5）完成二维装配图和主要部分零件图； 6）完成论文的撰写、修改和定稿； 7）交付相关的电子文档及纸质图纸，提交论文纸质查重报告，查重率应低于30%； 8）整个毕业设计过程最少要填写5份毕业设计（论文）指导情况记录表。毕 业 设 计（论 文）任 务 书3对本毕业设计（论文）课题成果的要求包括图表、实物等硬件要求：按毕业设计的时间节点要求按期完成： 1）完成与本专业相关的英文翻译一篇数量要求在3000汉字以上，并附原文，原文为PDF格式； 2）开题报告一份，总字数不少于3000汉字； 3）撰写4000汉字以上的设计说明书（格式同毕业论文）一份，中文摘要300汉字左右，外文摘要约250个词左右，格式应符合规范化要求； 2张A0号图纸。4主要参考文献：主要参考文献：1冷冲压模具改进设计分析案例J.陈克忠.企业科与发展.2013（08）：26-302李大鑫，张秀锦.模具技术现状与发展趋势综述J.模具制造，2005 （2）：1-4.3赵丹阳，宋满仓，王敏杰.模具现代制造技术综述J.模具制造，2003（8）：22-264挂钩冲压工艺及模具设计J. 钟翔山,黄志雄,肖军.世界制造技术与装备场. 2015(05)，1987:34-375 Ivana Suchy.Handbook of die Design J.McGraw-Hill, 19886 Ivana Suchy. Handbook of Die Design J. McGraw-Hill, 1998:66-70设 计（论 文）任 务 书5本毕业设计（论文）课题工作进度计划：起 讫 日 期工 作 内 容5本毕业设计（论文）课题工作进度计划：起 讫 日 期工 作 内 容2019年12月20日-2019年12月27日 指导教师对学生当面下发任务书，并对课题内容进行讲解，提出具体的任务要求，根据老师的指导意见，要求学生定期填写指导意见表并对照进度计划表同步自查完成进度。2019年12月28日-2020年1月10日 学生搜集资料，熟悉课题要完成的内容，提交开题报告及外文翻译的初稿。2020年1月11日-2020年2月28日 提交开题报告、外文参考资料及译文的定稿，对老师指出的问题在规定时间内及时修改，所有的格式必须满足毕设要求。2020年3月1日-2020年3月25日 进一步完善前期的各项材料，进行毕业设计的课题研究、具体方案设计等工作，具体要求：结合课题选择一付典型模具进行分析，选择一本合适的设计手册，按设计步骤进行计算说明书的撰写，徒手绘制模具草图开始模具图的设计，图中必须标注尺寸（包括压力中心、工作部分相关尺寸、闭合高度等）。2020年3月26日-2020年4月10日 对照计算说明书，开始正式的CAD总装图图纸绘制，并准备毕设中期检查。2020年4月11日-2020年4月25日 进一步完成课题的各项工作如：零件图的拆分、论文的修改、答辩PPT的准备等，并完成毕业论文的初稿。2020年4月26日-2020年5月10日进行毕业论文查重、评阅工作，学生根据要求完成论文定稿，准备毕业论文答辩。所在专业审查意见： 同意专业（系）负责人： 2019年12月26日学院审查意见： 同意学院负责人：2020年1月8日外文出处：Handbook of Die Design Ivana Suchy Copyright 2006 ISBN 0-07-146271-6 72th pages-77th pages 1外文资料翻译译文（约3000汉字）：1 外文资料翻译译文模具设计手册伊凡娜苏奇原文书号 ISBN 0-07-146271-6出版时间 2006年译文内容节选自第597-601页14-1 金属材料及其性能许多设计人员和工程师每天都在想是否他们在给定应用中使用了正确的材料，或者是否可以做出更好的选择，因为在材料选择领域，选择范围很大并且还在不断扩大。只要旧的成分不符合行业要求，就会开发新的材料。多年来，该行业收集了各种钢材，合金和其他材料的大量存货，可能使许多人担心他们可能看不到森林。因此，针对特定应用使用特定材料的决定通常是基于数小时的费力研究和评估。然而，一个想法可能经常潜伏在某个地方，也许是在我们的潜意识中，以至于可以做出更好，更便宜，更有利，更合适的选择。尽管现在已经有很多材料可供使用，但许多设计师可能并不熟悉它们，这一事实进一步削弱了已经很复杂的材料选择问题。有太多的材料要研究，有太多的事实需要评估。人们必须考虑一台计算机，以便能够批量存储数据，但仍可以进行某种选择性的控制和评估属性，这是一种不太可能的组合。没有人期望计算机思考，也没有人期望人们像计算机那样存储数据。要为存在的问题选择合适的材料，必须首先评估材料特性。与实际用途相比，应该对极限特性的劣势进行调查。如果有益的方面不是太有益，则应加以研究，以实际损害它们应该增强的过程。这可能经常会令人惊讶地发生。例如，对于摩擦质量而言理想的材料可能在仅需要一定摩擦量的操作中失败。否则，具有高弹性极限的材料将对切割过程有害，在该过程中，其行为可能像口香糖。还应该调查完全有害的属性，以比较其影响范围和实际有用程度。有些材料太脆，但是如果在需要脆性的地方使用，它们可能是一个很好的选择。另一种材料可能会遭受过度的回弹或缺乏回弹，因此应选择其应用以适合此类功能。如前所述，选择范围很广，正确的选择会变得复杂而复杂。14-1-1 金属冶金在搜寻材料丛林时要评估的第一方面是特定原料所经历的冶金过程，以及所含添加剂的数量和影响。金属处于退火状态时，由沉积在低合金铁基体中的碳颗粒混合物组成。在这种状态下，金属易于加工并且相对柔软。在热处理过程中，当在1400至2300 度 附近经受高温时，金属会被奥氏体化。它的一些碳含量熔化并溶解在铁基质中。在冷却或在水，油，空气或熔融盐中淬火后，会发生马氏体转变，从而产生硬而脆的物质。即使现在通过添加溶解的碳使基础铁合金的合金化程度更高，该基础铁合金仍会遭受残余应力，并且远不足以充当工具的功能。金属在300至1200度的温度下经受另一个加热循环，称为回火。回火可缓解一些残余应力，同时沉淀出一部分合金元素。增强了材料的韧性，保护了成品免受切割和类似操作的冲击。14-1-1-1框钢。框钢始终是低碳或中碳钢。当倒入锭模中时，它会在其周围迅速凝固，从而使剩余的钢在中间“关闭”到表面的通道。没有与外部的连接，气体被截留在锭块中，并以小气泡的形式散布。在凝固的铸锭中，这些小气泡在材料内形成微小的空腔，从而扰乱了其结构。带框产品的表面可能是完美的，光滑的并且具有高光洁度。但是，由于很少的内部口袋会影响材料的整体性，因此内部材料可能易于损坏。14-1-1-2镇定的钢铁。镇静的钢不会受到内部气泡的影响，因为调节了凝固过程，使其不产生气泡。凝固时，整个锭块从顶部开始沿其轴心在其质量中心形成凹痕。这种印象不是很深，但是必须丢弃该部分的材料。镇静钢通常是碳含量较高或合金化程度更高的钢。它们的表面光洁度大多较差。在边缘钢中不含大量硅（有时不含硅）的情况下，镇静钢中的硅含量超过0.15。硅有助于材料的脱氧和脱气。14-1-2 Fe-C相图Fe-C或铁的Fe 3 C相图表示钢水材料内的铁和碳之间的关系，记录在凝固的质量变化。这些过程被分配给不同的温度范围，并进一步受碳含量的影响，它们会影响材料的结构及其在每个特定阶段的热处理反应（图14-1）。固化时，多余的碳可能以石墨或碳化铁Fe 3 C 的形式分离，也称为渗碳体（含6.67C）。与其他类型的碳相比，碳化铁非常坚硬，不易延展，并且容易受到材料内应力的影响。铁素体（一种 铁）是一种铁磁性材料，非常易延展，抗张强度低于45.000 lb / in。2。碳在铁素体中的溶解度非常有限，因为铁素体的立方结构以及原子间的扁圆空间无法进行充分的改性，甚至不能包含非常小的碳原子。图14-1 FeC相图。铁素体类似于奥氏体或g铁，即使后者的原子间隔更密。这就是为什么在加热周期中，当发生从铁素体相到奥氏体的转移时，材料中的收缩可能会达到0.29。就残余应力的产生而言，这在热处理中具有相当重要的意义。奥氏体不是铁磁性的。铁（有时称为铁氧体）与铁氧体非常相似。它是固溶体，是指二元或更复杂合金的均质固体，其化学组成可以在一定范围内变化，而无需随后对其性能进行修改。这种溶液的晶格与其成分之一相同。 相图是评估大多数钢材各种热处理工艺的基本工具。它们的范围如图14-2所示，其中它们对温度和碳含量的依赖性很明显。14-1-3金属材料中的添加元素当溶解在铁基质中时，各种金属和非金属元素具有影响和改变最终材料质量的能力。一些添加剂使金属更脆，另一些使它更具延展性，还有一些在效果上仍存在争议。根据添加剂对金属材料的影响，它们可以分为三个基本组：1. 对材料质量有害的添加剂2. 利于材料质量的添加剂3. 合金添加剂图14-2 FeC相图。热处理数据。14-1-3-1对材料有害的添加剂。脱氧过程中留下的少量副产物以夹杂物的形式保留在金属含量内。这些通常是氧化物，硅酸盐，铝酸盐和硫酸盐，它们可能是 内生类型，或从内部产生的类型 外来类型，由于外部原因（例如熔化环境和机械）而无外来产生当夹杂物过多或分布不均时，这些夹杂物会影响材料的机械性能，使其抗疲劳性和韧性降低。铝的氧化物和氮化物通常分布均匀。它们改善了晶粒结构和材料的可拉伸性。然而，大多数对钢的质量和机械性能有害的其他夹杂物是不希望的，并且试图去除它们或最小化其影响是普遍的。其他有害元素是氢，氮，氧，磷和硫。氢（H）。在制造过程中，该元素可能被截留在熔融物料中。在固化阶段，大部分的氢会蒸发，直到只有三分之一的原始量留在材料中。这种氢并不会保持完整，而是会努力从熔体中分离出来，并被亚微观缺陷，间隙杂质，空位或微孔，界面或晶界吸引。在那里，它被金属的凝固物锁定并被其压缩，在压力作用下被保留，直到后来该材料在该力作用下破裂。这种破坏性行为称为氢脆。镍含量低的低合金钢尤其容易出现这种缺陷。可以通过退火工艺从钢中除去氢，在该过程中，将材料加热足够的时间并保持在该温度下，直到氢含量减少为止。防止氢而不是去除氢的另一种制造方法是真空铸造。据认为但尚未完全证明，氢能够与材料缺陷（例如微孔，晶界或界面，位错，空位或取代和间隙类型的杂质原子）发生主动相互作用。大量实验表明，杂质实际上起着氢陷阱的作用，这种元素被氢陷阱吸引，形成了稳定的双原子络合物。氮（N）。该元素容易溶解在钢水中，其含量取决于制造方法的类型。仅当金属固化足够缓慢时，才以氮化物Fe 4 N 的形式从固化材料中排出过多的氮。在这个过程的加快，氮构成内挥发性溶液一钢。随着氮含量的增加，金属从内部暴露于各种变化，从而导致其缺口冲击强度，延展性，可拉伸性和可成形性降低。总的来说，将这些变化归为一类称为金属时效。在常温下，老化会继续进行，并且可以通过将金属加热到730至900度来加速。易老化的金属包括“较软”的碳钢，如果在高温环境中使用，则可能会由于这种趋势而失效。 ，例如焊接的钢铁物体或锅炉零件。钢中的氮含量越低，其受老化影响越小。因此，应尽可能地迫使氮气形成温度稳定的氮化物。在某些材料中，有意将氮添加到奥氏体中，因为它可以改善和细化晶粒结构。在高铬钢中，氮是表面硬化中必不可少的元素。氧气（O）。在氧化期间，氧气可能会夹带在金属块中，这取决于材料中存在的一定量的氧气。由于碳的存在，未被这种机制利用的过量氧气不能简单地溶解自身并从金属含量中蒸发。在凝固的钢中，氧的含量约为0.05。氧气会降低材料的缺口冲击强度。它通常与各种夹杂物相连，例如氧化物（MnO，FeO，Al 2 O 3）或硅酸盐（SiO 2）。其他脱氧剂是铝，硅以及一些钛，锆和钙。磷（P）。磷可溶于熔体g中，从而提高了转变点A 3 的温度，同时降低了A 4的温度。钢中磷的含量很少超过0.1。像硫一样，它在固化过程中会从熔体中分离出来，从而损害了碳的溶解性。它对钢的机械性能的影响包括对缺口冲击强度的负面影响，促进脆性和削弱可焊接性。硫（S）。该元素与铁形成硫化物FeS，铁不溶于固化的熔融物料中。受凝固机制的排斥，硫化物迁移至凝固最慢的区域，该区域位于铸锭的顶部，围绕其中心轴集中。硫化物的作用包括包裹材料的奥氏体晶粒结构并削弱其内聚力，这会导致晶间裂纹。它们在较高的工作温度下会增加脆性，并降低材料的韧性，强度，延展性和残渣性。如果存在锰，硫容易与锰结合。它在大约3000 度的高熔融温度下形成MnS 。大部分硫化物与矿渣一起从材料中排出14-1-3-2对材料有益的添加剂。铜，锰和硅是对钢有积极影响的元素，可增强在广泛应用中有利的性能。铜（Cu）。该元素减慢了再结晶速度，并略微提高了成品材料的韧性。它通常以各种矿石成分的形式或从添加到过程中的金属屑进入金属。从数量上讲，铜几乎不会超过0.2。约0.1的用量可改善耐腐蚀，耐候性和湿度的能力。大量的铜根本没有好处，因为它们会增加材料表面在热加工过程中开裂的趋势。锰（Mn）。锰是一种脱氧剂和抗硫剂，在钢结构中最常用的含量为0.1到0.8。当溶解在材料的铁素体中时，它会稍微增加其韧性和强度，同时降低其脆性并改善可锻性。少量溶解在渗碳体中的锰可增强其稳定性。共析物浓度显示出碳对锰含量的显着依赖性。随着百分比的增加，碳的数量减少，反之亦然。锰进一步降低了重结晶速度，同时降低了该过程发生的温度范围。但是，锰本身不能作为材料脱氧的适当添加剂，因为它不能防止碳与凝固合金的反应。无限制的碳作用会产生未完全杀死的材料，在假定被杀死的情况下，这可能会对以后制造它的零件有害。为了帮助该过程，必须包含硅，脱氧剂或硅和铝的组合。其他脱氧剂是钛，锆和钙。硅（Si）。通常以高达0.5的量添加脱氧剂。它提高了铁素体电阻，但降低了材料的可成型性和可加工性，同时改善了热成型性能。所有深冲钢必须含有少量的受控硅。否则会影响绘图过程。像锰一样，硅控制着共析钢和奥氏体钢中的碳含量，使其含量取决于其百分比。硅进一步控制碳在基材中的适当溶解，这使得该添加剂特别适用于铸铁的生产。特种钢含有高达1.5至2.5的硅，在这种情况下，它们的淬透性，强度和韧性得到增强。硅的添加量很大时，可以改善材料的电性能，因此有时将这些钢称为电工钢。钢铁冶金中的14-1-3-3 合金添加剂。在炼钢实践中要考虑的另一组材料是合金元素。铝（Al）。该元素与其他元素（如钛，锆和钙）一起是极好的脱氧剂。它还用于控制晶粒尺寸。钴（Co）。少量的钴有助于合金钢的热硬度。然而，大量钴是不利的，因为它降低了材料的韧性，增加了其脱碳的趋势，并提高了临界淬火温度。铬（Cr）。该元素增加了硬度渗透的深度以及材料对热处理的响应。除不锈钢含量为12至25的不锈钢外，通常的含量为0.5至1.5的Cr。在不锈钢中，铬通常与镍配对，从而使合金具有抗腐蚀和抗氧化性。高铬含量会降低可磨性，同时会提高材料的硬化温度，这可能会导致热处理零件变形。lum（Cb）。effect的作用与钛相似，可防止有害的碳化物沉淀而引起晶间腐蚀。铅（Pb）。铅提高了可加工性，其添加量为0.15至0.35。它必须细分散在材料中。钼（Mo）。该元素有助于增加硬度，同时增加钢的韧性。通常范围为0.1至0.4。少量钼有助于材料的韧性和深度硬化性能。在较高的浓度下（例如用于高速钢的浓度），在某些情况下会代替钨。钼将保护材料免受蠕变影响并提高其热硬度。镍（Ni）。尽管可能会发现镍含量高达35的合金钢，但在钢中发现的镍含量为1-4，例如被称为“超级合金”的钢，例如镍含量为67的蒙乃尔合金，镍含量为77的因科镍合金和哈氏合金D占85。镍提高了材料的韧性和强度，以及在低温下的耐磨性和抗冲击性。碲（Te）。碲的用量约为0.05，可改善可加工性。钛（Ti）。钛对co的影响范围相近，因此可以使钢铁材料抵抗碳沉淀的有害影响。当添加到低碳钢中时，钛使其更适合瓷釉。钨（W）。这种元素通常以17到20的量大量使用，通常与铬和其他合金元素结合使用。它是高速钢的基本成分，由于钨具有良好的热硬性，因此即使在高温下也可以保持其硬度。在遇到高温环境或需要相当大的耐磨性的地方，钨是不可替代的。钨所占的百分比较少，可以产生细密的材料晶粒。钒（V）。当添加到钢中时，钒的含量通常为0.15至0.20，钒可阻止晶粒长大并细化碳化物组织，从而改善可锻性。钒还增强了材料的抗冲击性，并提高了其硬度以及耐磨性。钒过多会降低材料的可磨性。2外文资料原文（与课题相关，至少1万印刷符号以上）：2外文资料原文Handbook of Die DesignIvana SuchyOriginal ISBN 0-07-146271-6Published in 2006Excerpt from 60114-1 METAL MATERIALS AND THEIRPROPERTIESMany designers and engineers wonder on a daily basis if they are using the correct mater- ial for a given application or if a better choice could be made, because in the field of mate- rial selection the choices are vast and are continuously expanding. New materials are developed whenever the old composition does not meet the industry requirements.Over the years the industry assembled an impressive inventory of various steels, alloys, and other materials, causing perhaps many to fear that they may not see the forest for the trees. Therefore, the decision to use a particular material for the given application is often based on hours and hours of laborious research and evaluation. And yet an idea may often lurk somewhere, perhaps in our subconscious, that a better, cheaper, more advantageous, and more appropriate selection could have been made.The already complex problem of material selection is further impaired by the fact that even though so many materials are now available many designers may not be acquainted with them in detail. There is just too much material to be studied, with too many facts to be assessed. One has to have a mind of a computer to be able to store data in bulk and yet exer- cise some sort of selective control and evaluating properties, which is quite an unlikely combination. Nobody expects the computer to think and nobody should expect a person to store data the way a computer does.To select a proper material for an existing problem, the material characteristics must be evaluated first. Limiting properties should be surveyed for a proportion of their disad- vantage, compared to apractical usefulness. Beneficial aspects should be looked into, if theyre not overly beneficial, to actually impair the process they are supposed to enhance. This may happen surprisingly often. For example, a material perfect for its frictional qual- ities may fail in operations, where only a certain amount of friction is necessary. Or a mate- rial of high elastic limits will be detrimental to the cutting process, where it may behave like chewing gum.Outright harmful attributes should be surveyed as well, to compare their spectrum of influence to the degree of actual usefulness. Some materials are too brittle, but if used where brittleness is needed, they may prove to be an excellent choice. Another material may suffer from excessive spring-back, or lack of it, and its application should be selected to suit such capabilities. As already said, choices are vast and proper selections can become complex and intricate.14-1-1 Metallurgy of MetalsThe first aspect to be evaluated when searching through the material jungle is the metal- lurgical process the particular stock has been subjected to, along with the amount and influ- ence of additives it contains.Metals, when in their annealed form, consist of a mixture of carbon particles, deposited within a base of low-alloyed iron. In such a state, metals are easily machinable and relatively soft. During heat treatment, when subjected to high temperatures in the vicinity of 1400 to 2300F, the metal is austenitized. Some of its carbon content melts and dissolves in the iron matrix. On cooling down, or quenching in either water, oils, air, or molten salts, a martensitic transformation occurs, producing a hard and brittle substance. The base iron alloy, even though now considerably more alloyed by the addition of dissolved carbon, suffers from residual stresses and is far from being tough enough to function as an element of tooling.The metal is subjected to another heating cycle, which is called tempering, at tempera- tures between 300 and 1200F. Tempering relieves some residual stresses, while precipi- tating a portion of alloyed elements. Toughness of the material is enhanced, protecting the finished product from the shock of an impact in cutting and similar operations.14-1-1-1 Rimmed Steel. Rimmed steel is always low-carbon or medium-carbon steel. When poured into the ingot mold, it solidifies quickly around its periphery, which leaves the remaining steel in the middle “shut off” the access to the surface. Without a connection with the outside, gases become entrapped within the mass of an ingot, dispersed in the form of small bubbles. In a solidified ingot, these small bubbles form tiny cavities within the material, disturbing its structure.The surface of a rimmed product may be perfect, smooth, and of a high finish. But the inner material may be damage-prone, owing to little inner pockets affecting the unity of the material.14-1-1-2 Killed Steel. Killed steel does not suffer from the emergence of inner gas bub- bles, as the solidification process is regulated not to produce them. On solidification, the whole ingot begins to form an indent in the center of its mass alongside its axis, starting from the top. This impression is not of a great depth, but the material from that portion has to be disposed of. Killed steels are usually those containing either higher carbon content or those that are more alloyed. Their surface finish is mostly inferior.Where rimmed steels do not have a significant amount of silicon (sometimes they have none), the silicon content of killed steels is over 0.15 percent. Silicon aids in deoxidation and degasification of the material.14-1-2 FeC Phase DiagramThe FeC or FeFe3C phase diagram represents the relationship between the iron and car- bon within the molten steel material, recording changes in the solidifying mass. Theseprocesses, assigned to various temperature ranges and further influenced by the carbon con- tent, influence the structure of material and its reaction to heat treatment during each par- ticular phase (Fig. 14-1).On solidification, the excess carbon may be segregated in the form of either graphite or iron carbide Fe3C, also known as cementite (containing 6.67 percent C). Iron carbide, when compared to other types of carbon, is very hard, nonductile, and readily affected by stresses within the material.Ferrite, the a iron, is a ferromagnetic material, quite ductile, with tensile strength under 45,000 lb/in.2. Carbons solubility within ferrite is very limited, because the cubic structure of ferrite, with oblate spaces among atoms, cannot be modified enough to include even a very small atom of carbon.FIGURE 14-1 FeC phase diagram.Ferrite is similar to austenite, or g iron, even though the latters atoms are more densely spaced. Thats why during the heating cycle, when the transfer from the ferrite phase to austenite takes place, contractions within the material amounting to some 0.29 percent may be encountered. This has a considerable importance in heat treatment, with regard to the development of residual stresses. Austenite is not ferromagnetic.iron, sometimes called d ferrite, is quite similar to ferrite. It is a solid solution, which means a homogeneous solid mass of a binary or more complex alloy, the chemical composi- tion of which may be altered at a certain range without subsequent modification of its prop- erties. The crystalline lattice of such a solution is the same as that of one of its constituents.The phase diagram is the basic tool of evaluation of various heat-treating processes for the majority of steels. Their ranges are shown in Fig. 14-2, where their dependence on tem- perature and carbon content is obvious.14-1-3 Additive Elements Within the Metal MaterialVarious metallic and nonmetallic elements, when dissolved within the iron matrix, have the capacity of affecting and altering the qualities of the finished material. Some additives make the metal more brittle, others make it more ductile, and some are still controversial in their effect.According to the influence of additives on the metal material, they may be divided into three basic groups:1. Additives detrimental to the material quality2. Additives beneficial to the material quality3. Alloying additivesFIGURE 14-2FeC phase diagram. Heat treatment data.14-1-3-1 Additives Detrimental to the Material. Small quantities of byproducts left from the deoxidating process remain within the metal content in the form of inclusions. These are most often oxides, silicates, aluminates, and sulfates, and they may be of Endogenous type, or those produced from within Exogenous type, produced from without, due to external causes, such as the melting environment and machineryWhere they are too numerous or unequally distributed, these inclusions affect the mechanical properties of the material, making it less fatigue-resistant and less tough. Oxides and nitrides of aluminum are usually distributed evenly; they improve the grain structure and the drawability of material. However,other inclusions, mostly detrimental to the quality and mechanical properties of steel, are undesirable, and an attempt to remove them or minimize their effect is prevalent. Other harmful elements are hydrogen, nitrogen, oxygen, phosphorus, and sulfur.Hydrogen (H). This element may become entrapped within the molten mass in the manufacturing process. During the solidification phase, most of the hydrogen evaporates, until only about one-third of the original amount is left within the material. This hydrogen does not remain intact but strives to separate itself from the melt, being attracted by areas of submicroscopic defects, interstitial impurities, vacancies or microvoids, interfaces, or grain boundaries. There, locked in and compressed by the solidifying mass of metal, it is retained under pressure, until the material cracks later under the force. This type of destructivebehavior is called hydrogen embrittlement. Low-alloy steel with some nickel content is especially susceptible to such a defect.Hydrogen may be removed from steel by an annealing process, where the material is heated for an adequate time and held at such a temperature until the hydrogen content is dimin- ished. Another manufacturing method of hydrogen prevention rather than removal is vacuum casting.It is believed, but not yet completely proved, that hydrogen is capable of active interac- tion with material defects, such as microvoids, grain boundaries or interfaces, dislocations, vacancies, or atoms of impurities of substitutional and interstitial types. A large number of experiments have shown that impurities actually act as hydrogen traps, to which this ele- ment is attracted, to form stable, diatomic complexes.Nitrogen (N). This element is readily dissolved in the molten steel, and its amount depends on the type of manufacturing method. Excessive nitrogen is expelled from the solid- ifying material in the form of nitride Fe4N, only if the metal solidification is adequately slow.At speeding up of this process, nitrogen forms a volatile solution within the a steel.With greater content of nitrogen, the metal is exposed to various changes from within, which produce a decrease in its notch impact strength, ductility, drawability, and formability. Overall, these changes as grouped together are called aging of metal. Aging continues to progress at regular temperatures and may be accelerated by heating the metal to some 730 to 900F. Metals susceptible to aging include “softer” carbon steels, which may fail in service due to this tendency if used in higher-temperature environments, such as welded steel objects or boiler parts.The lower the amount of nitrogen within the steel, the less affected by aging it becomes. Therefore, the nitrogen should be forced to form temperature-stablenitrides wherever possible.In some materials, nitrogen is purposely added to the austenite, since it improves and refines the grain structure. In high-chromium steels, nitrogen is an indispensable element in case hardening.Oxygen (O). Oxygen may become entrapped within the metal mass during the period of oxidation, which depends on a certain amount of it being present within the material. The excess oxygen not utilized by this mechanism cannot simply dissolve itself and evaporate from the metal content, being restricted by the presence of carbon. In the solidified steel, the amount of oxygen may be found at some 0.05 percent.Oxygen lowers the notch impact strength of the material. It is usually tied to various inclusions, such as oxides (MnO, FeO, Al2O3) or silicates (SiO2). Other deoxidants are alu- minum, silicon, and somewhat titanium, zirconium, and calcium.Phosphorus (P). Dissolvable within the melt g, phosphorus raises the temperature of the transformation point A3 while lowering that of A4. The amount of phosphorus within the steel rarely exceeds 0.1 percent. Like sulfur, it separates from the melt during the process of solidification, impairing the solubility of carbon. Its effect on the mechanical properties of steel consists of negatively affecting the notch impact strength, promoting brittleness, and impairing weldability.Sulfur (S). This element forms a sulfide FeS with iron, which remains insoluble within the solidifying molten mass. Repelled by the solidification mechanism, sulfides migrate to the areas of slowest solidification, which are located at the top of the ingot, concentrated around its central axis.Sulfides action consists of their enwrapping the materials austenitic grain structure and impairing its cohesion, which results in an intergranular cracking. They increase the brittleness at higher working temperatures and decrease the toughness, strength, ductility, and machinabity of the material.Sulfur readily combines with manganese, if the latter is present. It forms MnS at high meltingtemperature of approximately 3000F. Most of this sulfide is expelled from the material along with the slag.14-1-3-2 Additives Beneficial to the Material. Copper, manganese, and silicon are ele- ments that influence steel positively, enhancing properties that are advantageous in a wide range of applications.Copper (Cu). This element slows down the recrystallization rate and slightly improves the toughness of the finished material. It usually gets into the metal in the form of an ingre- dient of various ores or from the metal scrap added to the process. Quantitatively, copper hardly ever exceeds 0.2 percent. Amounts ranging at about 0.1 percent improve the resis- tance to corrosion, weathering effects, and humidity. Larger amounts of copper are not ben- eficial at all, as they enhance the tendency of the material surface to crack during heat working.Manganese (Mn). A deoxidant and sulfur repellant, manganese is used most often in quantities of 0.1 to 0.8 percent within the steel makeup. When dissolved in the ferritic sub- stance of the material, it somewhat increases the toughness and strength of it, while decreasing its brittleness and improving forgeability. A small portion of manganese dissolved in cemen- tite enhances its stability. Eutectoid concentration displays a marked dependency of carbon on manganese content; with increased percentages, the amount of carbon decreases and vice versa. Manganese further lowers the recrystallization speed while lowering the temperature ranges at which this process takes place as well.However, manganese alone is not an adequate additive for deoxidation of the material, as it is not capable of preventing the reaction of carbon with the solidifying alloy. An unre- stricted carbon action produces a material that is not completely killed, which may be detri- mental to parts made out of it later under the assumption that it is killed. To aid the process, an inclusion of silicon, a deoxidant, or a combination of silicon and aluminum is necessary.Other deoxidants are titanium, zirconium, and calcium.Silicon (Si). This is usually added to serve as a deoxidant, in quantities of up to 0.5 percent. It increases the ferritic resistance but lowers the materials formability and machinability, while improving hot-forming properties. All deep-drawing steels must have controlled, low amounts of silicon; otherwise the drawing process will be impaired.Like manganese, silicon controls the amount of carbon in eutectoid and austenitic steel, making their quantities dependent on its percentage. Silicon further controls the proper dis- solving of carbon within the base material, which makes this additive especially useful in the production of cast iron.Special steels contain up to 1.5 to 2.5 percent silicon, in which case their hardenability, strength, and toughness are enhanced. Silicon, when added in such a large percentage, improves the electrical properties of the material, for which these steels are sometimes called electrical steels.14-1-3-3 Alloying Additives in Steel Metallurgy. Another group of materials to consider in steelmaking practice are alloying elements.Aluminum (Al). This element is an excellent deoxidizer, along with other elements such as titanium, zirconium, and calcium. It is also utilized for controlling the grain size.Cobalt (Co). Cobalt in small amounts supports the hot hardness of alloyed steel. However, in large amounts cobalt is not beneficial, as it reduces the toughness of the mate- rial, increases its decarburization tendency, and raises the critical quenching temperature.Chromium (Cr). This element increases the depth of hardness penetration and the mate- rials response to heat treatment. The usual content is 0.5 to 1.5 percent Cr, with the excep- tion of stainless steels,which contain the amounts of 12 to 25 percent. In stainless