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机械毕业设计全套

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JX05-074@自行车用无级变速器结构设计,机械毕业设计全套

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湘潭大学 兴湘学院 毕业论文 题 目： 自行车用无级变速器结构设计 专 业： 机械设计制造及其自动化 学 号： 2010963142 姓 名： 朱杨华 指导教师： 聂松辉 完成日期： 2014 年 5 月 29 日 nts湘潭大学 兴湘学院 毕业设计说明书 题 目： 自行车用无级变速器结构设计 专 业： 机械设计制造及其自动化 学 号： 2010963142 姓 名： 朱杨华 指导教师： 聂松辉 完成日期： 2014 年 5 月 29 日 nts外文翻译 半固态成型 ： 竞争 来自 汽车复杂零件的锻造机 Q. ZHU1, S. P. MIDSON2 1.英国康明斯涡轮增压技术有限公司，圣安得烈路，哈德斯菲尔德， Hd1 6RA S； 2.美国铝复杂组分公司，科罗拉多州丹佛贾森街道 2211 南， 80223， 2010 年 5 月 13日收到 ; 2010 年 6 月 25 日接受 摘 要 叶轮制造的最新技术被称为半固态成型（ SSM） 。它是 康明斯涡轮增压技术有限公司与铝复合元件公司 一起 开发 ， SSM 压缩机轮的一种方式 。它能使 铸造和加工固体之间（ MFS）铝合金车轮 ， 实现成本和耐久性的地 方 。 实验结果 表明， SSM 材料具有优良的显微组织和力学性能 ，这些都 高于 MFS 材料。 测试包括耐久性的组分测试，使用加速的速度周期测试，证明 SSM 压缩机轮子比 铸造 的等值 更耐用和接近 MFS 叶轮 。为了使 半固态处理 进一步挑战 ，对 汽车行业中 制造 成本和其他成分复杂等材料的耐 久性进行了讨论。 关键词 ： 铝合金 ; 半固体造型 ; 耐久性 ; 汽车复杂组分 ; 蒸气增压器压缩机轮子 1 引言 柴油和汽油发动机是造成的排放和全球变暖的 一个 重要来源。为了提高燃油效率和减少排放 ， 汽车轻量化是一种有效的方法 .。 半固态成型（ SSM）已成功帮助 ，减轻 汽车零部件 的 重量 ，明显 改善的机械性能 。 所以，可以用小或更薄的壁 零件 。汽车零部件已成功 用 SSM。达斯古普塔 1 总结了最普遍的应用如下： 1) A357-T5,2)自动传输使换中档杠杆 A357-T5， 3)发动机装配 A357-T5， 4)引擎托架 1 800 g A357-T5， 5)上部控制臂 A356-T6， 6)悬浮 A357-T5， 7)引擎托架 720 g A357-T5， 8)引擎托架 2400 g A357-T5 和 9)柴油引擎 A356- T5 泵体加油路轨。 发动机技术发展的另一种有效的提高 燃油效率和减少 排放。 加 气压比率到 发动机方式 能够 进一步提高燃油效率 和 减少 排放的目的。增加 气压 可以通过在一个涡轮增压器压缩机轮 来 实现。压缩机轮需要非常复杂的叶片 ， 几何实现高压力比。 应付 250 C 和重大温度差时， 压缩机轮承受的旋转速度高达 200 000 转 /分钟。 除 机械力量和温度能力的要求之外 ， 由于在速度周期上的刀片的变化和振动， 疲劳是一种典型的失效模式 。 这种组合 的复杂的几何形状和 坚韧操作条件 ,意味着调制解调器压缩机轮子要求最佳的物质技术。 几十年来，压缩机的车轮含有铝，硅和铜 的合金 。 要达到指定的耐久性目标，然而，制约他们的发行速度，即是必要的。 由于铸 造 缺陷 ， 在操作过程中减少 了发动机的效率 。 因此 ，固体 (MFS)或锻件压缩机轮子的 开发 ，克服铸件瑕疵问题。在耐nts久性的改善也意味 MFS 轮子可能可靠地跑以更高的速度，增长的燃料效率和减少 排放 。缺点是 MFS 铸造 比较 昂贵。 因此，半 固态成形加工（ SSM）应用开发的 制造过程中， 在铸造和 MFS 铝合金之间车轮 ， 去实现成本和耐久性能。由于压缩机轮几何形状复杂，精度控制的要求和严格的操作条件，制造压缩机轮可能是 SSM 最困难的过程。在这项工作 2 涡轮增压 最近 涡轮增压 技术广泛用于柴油发动机和汽油发动机 ， 直接喷射技术也一起发展。对于新汽车涡轮增压器的应用量（合适的） 。如图 1 所示，在过去 10 年 1999 年 -2004年 稳定增长约 10%和 2004 年 -2009 年约 5%， 平均年增长率约 7%。在 2004 年 -2009 年 较低的增长率 ， 主要是由经济衰退引起的 。 自 2008 年 以来，未来 10 年预计年增长率将有约 8%。 2007 年蒸气增压器新车的世界总宽容量大约是 20 百万个单位，相当于 6.8 十亿USD。 图 1 全球 涡轮增压发动机 市场（首次适应卷 ） 涡轮增压器 可以通过压缩机轮 子 有效地增加气压，这是由通过废气涡轮轴 排气 。图2 显示了一个典型的废气旁通增压器。 压缩机轮子的转动 速度可高达 200 000 r/min。进一步增加的速度是提高效率和燃油经济性。 然而，转动速度由压缩机和涡轮叶轮的材料 物产生限制。 涡轮增压器故障主要是由压缩机或涡轮机在 高温条件下 引起疲劳 。 nts 图 2 典型的废气旁通增压器概述 nts3 SMM 制造涡轮增压器压缩机轮的挑战 涡轮增压器压气机叶轮几何的设计是非常复 杂，为了满足特定的效率和耐久性的要求。图 3 给出了一个典型的压缩机叶轮的设计。叶片 长度与叶片厚度比约为 25， 这使得它在 SSM 难填补的叶片和中央集线器刀片的质量比可以达到 80 左右，同时这使得它很难获得满意的叶片和轮毂组织。此外 ， 叶 片的曲度在处理以后 SSM 模子难拆卸。 因此，模具设计，浇注系统设计及模具温度控制和流道系统 是达到一个成功的结果的关键参量2。另外 ，材料也必须 经过仔细挑选，以满足 在严格操作条件下符合压缩机轮子的耐久性的严密要求。 图 3 概述（ a）、剖面图（ b）典型的压缩机 砂轮 nts4 材料的选择 材料的选择 是决定开始的物理性能如热导率，热系数和 合金密度保证当前组分设计有效性 。认为 3XX 铸造铝合金可用于目前压缩机轮的设计。可用所有 3-33 数据的SSM 的力学性能 和 铸铝合金比较后， 319s 合金被选择制造压缩机轮子 。图 4 显示 319s合金具有合理最好的和一致的拉伸强度和伸长率。从纯粹的拉伸性能 的观点， SSM A201也显示了可喜的成果 。 因此， SSM A201 试验 ， 更好的实现了文学强度和延性比。然而，SSM A201 没有 市售的 。 所以用于制造压缩机轮仍然是 SSM 319s 合金 。 图 4 SSM 铝合金 的拉伸性能比较永久模铸造的（ PM） 5 结果 在 表 1 中给出 了 SSM 压缩机轮 选 择 合金 319s 化学成分。图 5 显示 SSM 319s 压缩机轮有 优越 的 抗 拉伸强度和延 展 性 。在 2618锻造热处理 T61的条件下用于压缩机轮 的 c355和目前 354 接近。单轴疲劳试验结果表明，试样从一个平行的方向锻造 2618 合金的金属流动具有优良的耐疲劳性 ， 而在垂直方向有类似的疲劳性能 抵抗熔铸 355（ 6）。 金属化流程样品的取向之间这个区别主要出现从粗第二个阶段微粒的对准线。 改善疲劳在图6 小应变 中 可以看到 SSM 319s 在 铸 造 355 的 属性。 如图 7 所示， 已被证明组件的磁盘疲劳试验， 是由单轴的压缩应力与 R O 在从压缩机轮子的后面面孔用机器制造的盘样品进行 。在涡轮增压器组件测试 中， 检测 的 细胞 受 康明斯涡轮增压技术的限制，结果列于图 8。 图 8 显示了铸造 c355， 2618 和 SSM 319s 相比的耐久性 。 SSM 319s 和伪造 2618nts压缩机轮之间，虽然他们都 优越 铸造 c355 的耐久性。 SSM 319s 和伪造的 2618 的这重大改善主要 来自材料 的改善和铸件瑕疵的排除，例如氧化物。 除对材料的完整性 ， 锻造和SSM 的改进清洁 。 锻造 2618 和 SSM 319s 比铸造的 C355 和 354.0 的 晶粒结构细化 和 显微组织 是对压缩机轮子的耐久性改善的另一贡献 (图 9)。 图 5 显示了 SSM 319s 铸造 优越的抗拉性能 c355， 354 和 319，与 锻造 2618 nts 图 6 通过铸造 SSM 319s 显示出 c355 与 锻造 2618 优越的 耐疲劳性 图 7 SSM 319s 显示出在铸造 c355 阻力优越的单轴疲劳 nts 图 8 SSM 319s 压缩机轮表现出在铸造 c355 压缩机轮与 锻造 2618 优越的耐久性 图 9 晶粒 结构的铸造 c355（ a）， 2618（ b）和 锻造 SSM 319s（ c） ，表明类似的 晶粒尺寸之间锻造 和 SSM 合金，而显著 小于 铸造合金 。 nts 5 执行总结 1）涡轮增压是实现大幅减排 和 燃油经济一个最成功的技术。涡轮增压发动机在过去 10 年 已经取得 大 约 7%的体积增加 ，并且 未来 10 年预测增长 8%。 2） SSM 已被成功地应用于生产极其复杂的几何涡轮增压器的压缩机车轮。 3） SSM 压缩机轮取得了拉伸 ， 疲劳性能 和部件的耐久性 。 所以， 它 接近 2618 锻造 ，优于铸造 c355。 6 未来的挑战 虽然 制造业的 SSM汽车零部件已取得重大进展 ， 研究人员努力开发新的合金和工艺，仍有需要更多的努力来满足工业要求。这些措施包括： 1） 更多选择的 合金 有汽车的工业应用不同要求，一些需要高 强度，而有些人可能需要高的热性能，疲劳性，耐腐蚀性和耐磨性。这些都需要不同的合金系统满足一个或多个工业应用的要求。 2） 高熔点合金系统 发展 SSM 是 最大的努力过程历史上以相对较低的熔化点、合金如铝和镁合金。一些努力和成功取得了高熔点点合金如钢 34 ，但进一步的研究需要发展的材料系统的铸铁，钢镍基合金。这些材料具有显着的比铝和镁合金密度更高，所以有更大的潜在节省更多的重量汽车零部件，从而更多的燃油经济性，和提高质量和性能，耐久性在 SSM 过程改进的光比合金。 3） 复杂的几何 部件 一些汽车零部件的复杂几何， 例如一个涡轮增压器压气机轮和发动机缸头，使得它很难实现严格的性能要求，在铸造锻坯加工效率 /成本。因此 ， SSM 几何组成有制造复杂的巨大潜力。非常低的剪切强度在半固态状态合金使它实现制造复杂的几何部件时浇注系统的合理设计与模具结构在低剪切强度达到可容纳相对较高的抗压强度。 4） 还原电流 SSM 元件成本 在使用 SSM 加工过程中减少零件的制造成本实现锻坯。然而，由于成本高制造原料棒料，复杂性浇注系统和模具结构以及相对高成本， SSM 组件的成本仍然显著高于铸造。因此，应作出努力，进一步达到降低成本棒料的原材料，设计和制造 浇注系统和模具结构和工艺 。 nts致谢 作者想 表达他们的 感谢 ， 在康明斯涡轮增压迈克尔凤博士对批判性阅读和科技有限公司本文的评论。多亏了安得烈 .杰克逊的铝成分复杂，开发工具和一般支持 成功地生产的 SSM 叶轮。 参考文献 1 达斯古普塔 R. C / / proc 第八间半固态会议合金和复合材料的加工。塞浦路斯， 2004。 2朱 Q，杰克逊一页的制造方法和制造装置涡轮机或压缩机轮 P。 wo2007 / 010181， 2007。 3刘博士研究 D 。上海：谢菲尔德大学， 2003。 4金属手册。的性能和选择：有色合金专用材料 M.。第 2 卷，第十版的金属公园 ,ASM， 1990。 5 wabusseg H，考夫曼 H， uggowitzer P J. C /chiarmetta g L，罗索 M.触发第六间会议半固态合金与复合材料加工。都灵意大利 2000。 777-782。 6 伯格斯马 C，托尔 M C， Evangelista E. C / Bhasin 一穆尔 J， K，年轻的 K P， midson 美国 PROC 第五间会议半固态合金与复合材料加工。金，科罗拉多州，美国， 1998： 149-155。 7红牛 m，佐丹奴 P， chiarmetta G L. C /chiarmetta g L，罗索 M.触发第六间会议半固态合金与复合材料加工。都灵意大利 2000。 325-330.。 8 卡丽 M， Blais 的， pluchon C. C / Bhasin K，穆尔 JJ， K P 的年轻， midson P.触发第五间半固态会议合金和复合材料的加工。金，科罗拉多州，美国， 1998：第十七条三十一。 9该 页 C / / Bhasin K，穆尔 J，年轻的 K P， midson 体育过程的第五间半固态合金加工中，复合材料。金，科罗拉多州，美国， 1998：第九十六。 10牛 X P，胡 B H，郝的 w C / Bhasin K，穆尔 J，年轻的 K P， S P midson 触发第五间半固体会议合金和复合材料的加工。金，科罗拉多州，美国， 1998： 141-148。 11 chiarmetta G. C /柯克伍德 D H，普瑞诺斯 P.处理第四间会议对合金和复合材料的半固态加工。谢菲尔德，英国， 1996： 204-207。 12 wendinger D B. C /柯克伍德 D H，普瑞诺斯 P.过程 ,第四间半固态合金加工中，复合材料。谢菲尔德，英国， 1996： 239-241。 13 witulski T，温克尔曼，希尔特 G. C /柯克伍德 D H，普瑞诺斯 P.触发第四间半固态加工方法合金和复合材料。谢菲尔德，英国， 1996： 242-247。 14 柴田 R， kaneuchi T，苏打 T. C /柯克伍德 D H，普瑞诺斯 P.触发第四间半固态加工方法合金和复合材料。谢菲尔德，英 国， 1996： 296-300。 15 gabathuler J P，迪策勒 C. C /柯克伍德 D H，普瑞诺斯 P.触发第四间半固态加工方法合金和复合材料。谢菲尔德，英国， 1996： 331-335.。 16 chiarmetta G. C / Bhasin K，穆尔 J，年轻的 K P， midson 美国 PROC 第五间半固态加工方法合金和复合材料。金，科罗拉多州，美国， 1998： 95。 nts 17 Fink R， witulski T. C / Bhasin K，穆尔 J，年轻 K P， midson 美国 PROC 第五间半固态加工方法合金和复合材料。金，科罗拉多州，美国， 1998： 557-564。 18 boero chiarmetta F， G，佐丹奴体育 C / / chiarmettaG L，罗索 M.过程第六间会议半固态加工合金和复合材料。都灵，意大利， 2000 581-586。 19 伯格斯马 C，卡斯纳 M E， E / Evangelista Cchiarmetta g L，罗索 M.触发第六间会议半固态合金与复合材料加工。都灵意大利 2000。 319-324。 20壮的 H，吴米，马 C Y C / / chiarmetta g L，罗索 M.触发第六间半固态合金加工中，复合材料。都灵，意大利， 2000 705-710。 21 卡丽 M 门纳 L， sztur C. C / / chiarmetta g L，罗索 M.触发第六间会议半固态加工合金和复合材料。都灵，意大利， 2000:187-194。 22 科普 R P，赢得了 G， Kallweit J. C / / chiarmetta g L，罗索 M.触发第六间会议半固态加工合金和复合材料。都 灵，意大利， 2000 687-691。 23 lorstad J L. C / / chiarmetta g L，罗索 M.程序第六国际米兰在半固态合金与复合材料的加工方法。都灵，意大利， 2000 227-233。 24罗索 M Romano E，佐丹奴体育 C / / Tsutsui Y，回答我，市川 K.触发第七间会议半固体合金和复合材料的加工。日本，筑波， 2002： 151156。 25龙 C，郑 C Q， schehata M T. C / Tsutsui Y，回答第七 M 川 K.过程间会议半固体合金和复合材料的加工。日本，筑波， 2002： 213-220。 26 de Freitas E，费拉奇尼 E G，皮费诉 C / / Tsutsui Y，回答我，市川 K.触发第七间会议半固体合金和复合材料的加工。日本，筑波， 2002： 233-238。 27 考夫曼 H， HLZL， uggowitzer P J. C / Tsutsui Y，回答我，市川 K.触发第七间会议半固体合金和复合材料的加工。日本，筑波， 2002： 617-622。 28 安达 M，佐藤 S，佐佐木 H. C / Tsutsui Y，回答我，市川 K.触发第七间会议半固态加工合金和复合材料。筑波，日本， 2002： 629-634。 29 OGRIS E， Lchinger H， uggowitzer P J. C / Tsutsui Y，回答我，市川 K.触发第七间会议半固体合金和复合材料的加工。日本，筑波， 2002： 713-718。 30 诱导的 T，普瑞诺斯 P， DH 柯克伍德 C / / Tsutsui Y，回答第七 M 川 K.过程间会议半固体处理的合金 nts Semi-solid moulding: Competition to cast and machine from forging in making automotive complex components Q. ZHU1, S. P. MIDSON21. Cummins Turbo Technologies Limited, St. Andrews Road, Huddersfield, HD1 6RA, UK; 2. Aluminium Complex Components Inc, 2211 South Jason Street, Denver, Colorado 80223, USA Received 13 May 2010; accepted 25 June 2010 Abstract： The very latest technique for impeller manufacture is called semi-solid moulding (SSM). Cummins Turbo Technologies Limited, together with Aluminum Complex Components Inc, developed SSM compressor wheels as a way of achieving cost and durability performance somewhere between that of cast and machined from solid (MFS) aluminium alloy wheels. Experimental results show SSM material has a superior microstructure and mechanical properties over cast and comparable to MFS materials. Component testing including durability testing, using accelerated speed cycle tests, proves SSM compressor wheels emerge as being significantly more durable than cast equivalents and approaching that of MFS impellers. Further challenges for semi-solid processing in manufacture of other complex components and other materials in automotive industry in terms of both cost and durability are also discussed. Key words: aluminum alloys; semi-solid moulding; durability; automotive complex component; turbocharger compressor wheel 1 Introduction Diesel and gasoline engines are one of the most important sources to cause emission and global warming. To increase fuel efficiency and to reduce emission, vehicle weight reduction is one of the effective ways. Semi-solid moulding (SSM) has successfully helped to reduce weight of automotive components due to the significant improvement of mechanical properties over cast, so, smaller or thinner wall parts can be used. Automotive components have been successfully manufactured by SSM. DASGUPTA1 has summarized the most popular applications as: 1) fuel rail of A357-T5, 2) automatic transmission gear shift lever of A357-T5, 3) engine mount of A357-T5, 4) engine bracket 1 800 g of A357-T5, 5) upper control arm of A356-T6, 6) suspension of A357-T5, 7) engine bracket 720 g of A357-T5, 8) engine bracket 2 400 g of A357-T5, and 9) diesel engine pump body of A356-T5. Engine technology development is another effective way increasing fuel efficiency and to reduce emission. Increasing the air pressure ratio to the engine is a way to achieve the objective of further improving fuel efficiency and reducing emission. One way to increase air pressure can be achieved by a compressor wheel in a turbocharger. The compressor wheel needs very complex blade geometry to achieve high pressure ratios. Compressor wheel withstands rotational speeds up to 200 000 r/min but must do so while coping with up to 250 C and a significant temperature gradient. In addition to the requirements of mechanical strength and temperature capability, fatigue is a typical failure mode of a compressor wheel in application due to changes in speed cycles and vibration of blades. This combination of sophisticated geometry and tough operating conditions means that the modern compressor wheels demand the best material technology. Compressor wheels for decades have been cast from alloys containing aluminum, silicon and copper. To achieve the specified durability targets, however, it is necessary to restrict their release speed, i.e. to reduce efficiency of an engine during operation due to cast defects. Therefore, the machined from solid (MFS) or forging compressor wheels have been developed to overcome the casting defect problem. The improvement in durability also means MFS wheel can run reliably at the higher speeds, increasing fuel efficiency and reducing emission. The downside is that MFS is significantly more expensive than casting. Therefore, semi-solid moulding (SSM) processing is applied to develop a manufacturing process that is a Corresponding author: Q. ZHU; +44-1484-832567; E-mail: Qiang.zhuC; Qiang.zhuTrans. Nonferrous Met. Soc. China 20(2010) s1042-s1047 ntsQ. ZHU, et al/Trans. Nonferrous Met. Soc. China 20(2010) s1042-s1047 s1043way of achieving cost and durability performance somewhere between that of cast and MFS aluminum alloy wheels. Due to the complex geometry, precision control requirement and severe operation condition of a compressor wheel, manufacturing compressor wheel may be one of the most difficult processes for SSM. In this work, development and results of SSM application in manufacturing compressor wheels are presented, as an example of SSM application in manufacture of complex geometric automotive components. 2 Turbocharging Turbocharging technology is widely used for diesel engine and recently also for gasoline engine together with direct injection technology development. The volume of turbocharger application for new vehicles (first fit) has steadily increased by about 10% between 1999 and 2004 and 5% between 2004 and 2009, leading to about 7% average annual increase rate in the past 10 years (Fig.1). The lower increase rate between 2004 and 2009 has been mainly caused by the economic recession since 2008 and it is expected that annual increase rate in the next 10 years will be about 8%. The total world wide volume of turbochargers in 2007 was about 20 million units for new vehicles, which was equivalent to 6.8 billion USD. Fig.1 Global turbocharged engine market (first fit volume) Turbocharger can effectively increase air pressure ratio through a compressor wheel, which is driven by turbine wheel through a shaft by exhaust gas. Fig.2 shows a typical wastegated turbocharger. The speed of rotation of the compressor wheel can reach as high as 200 000 r/min. Further increasing speed is desirable for improved efficiency and fuel economy. However, the rotation speed is limited by materials properties of the compressor and turbine wheels. Failure of a turbocharger is mainly caused by fatigue of the compressor or turbine wheel operated at high temperatures. Fig.2 Overview of typical wastegated turbocharger 3 Challenges of manufacturing turbocharger compressor wheels by SSM The geometry of a turbocharger compressor wheel is designed to be very complex in order to meet specific efficiency and durability requirement. Fig.3 presents a typical design of a compressor wheel. The ratio of blade length to blade thickness is about 25, which makes it difficult to fill the blade during SSM process, and the ratio of mass at central hub to blade can be about 80, which makes it difficult to get satisfied microstructure for both blade and hub simultaneously. In addition, the curvature of the blades makes it difficult to disassemble the SSM die after processing. Therefore, die design, runner system design and temperature control of the die and runner system are the key parameters to achieve a successful result2. In addition, materials must be also selected very carefully to meet the stringent requirements of durability of a compressor wheel under the severe operation conditions. Fig.3 Overview (a) and section view (b) of typical compressor wheel ntsQ. ZHU, et al/Trans. Nonferrous Met. Soc. China 20(2010) s1042-s1047 s1044 4 Materials selection Materials selection was started from determining the physical properties such as thermal conductivity, thermal coefficient and alloy density to ensure the validity of current component design. It was recognized that all 3XX cast aluminum alloys can be applied for currently designed compressor wheels. After comparison of all available data3-33 of mechanical properties for SSM and cast aluminum alloys, the 319s alloy was selected to manufacture compressor wheels. Fig.4 shows that SSM 319s alloy has reasonably the best and consistent tensile strength and elongation. From purely tensile property point of view, SSM A201 also shows promising results and therefore, trials were also conducted. Better strength and comparable ductility of SSM A201 than those in literature was achieved. However, SSM A201 was not commercially available so SSM 319s was still the alloy used to manufacture compressor wheels. Fig.4 Tensile properties of SSM aluminum alloys compared with permanent mould (PM) cast ones 5 Results Chemical composition of the selected alloy 319s for SSM compressor wheel is given in Table 1. Fig.5 shows that the SSM 319s compressor wheel had superior tensile strength and ductility over cast C355 and 354.0 currently used on compressor wheels and approaching those of the forged 2618 under the condition of heat treatment T61. Uniaxial fatigue testing results showed that samples cut from forged 2618 alloy in a parallel direction to the metal flow had superior fatigue resistance whereas in the perpendicular direction it had similar fatigue resistance to cast 355 (Fig.6). This difference between orientations of sample to metal flow mainly arises from the alignment of coarse second phase particles. Improvement of fatigue property of SSM 319s over cast 355 can also be seen at Table 1 Chemical composition of 319s (mass fraction, %) Element Min. Max. Copper (Cu) 2.0 3.0 Magnesium (Mg) 0.25 0.35 Silicon (Si) 5.0 6.0 Iron (Fe) 0.15 Nickel (Ni) 0.03 Zinc (Zn) 0.05 Titanium (Ti) 0.20 Manganese (Mn) 0.03 Lead+Tin (Pb+Sn) 0.05 Strontium (Sr) 0.01 0.05 Others (Each) 0.03 Others (Total) 0.1 Aluminium (Al) Bal. Fig.5 SSM 319s showing superior tensile properties over cast C355, 354.0 and 319 while comparable with forged 2618 Fig.6 SSM 319s showing superior fatigue resistance over cast C355 while comparable with forged 2618 small strains in Fig.6. This has been proven by component disk fatigue test, where uniaxial compressive stress with R0 on the disk samples machined from back face of compressor wheel was performed, as shown in Fig.7. Component testing in a turbocharger was carried out on gas stand testing cells at Cummins Turbo Technologies Limited and the results are given in Fig.8. ntsQ. ZHU, et al/Trans. Nonferrous Met. Soc. China 20(2010) s1042-s1047 s1045Life comparison between cast C355, forged 2618 and SSM 319s in Fig.8 shows a comparable durability between SSM 319s and forged 2618 compressor wheels, while they both have superior durability over cast C355. This significant improvement of SSM 319s and forged 2618 arises mainly from improvement of material integrity and the elimination of casting defect such as oxides. In addition to the material integrity and cleanliness improvement by forging and SSM, refinement of grain structure and thus microstructure of forged 2618 and SSM 319s compared with cast C355 and 354.0 is another contribution to the durability improvement of compressor wheels (Fig.9). Fig.7 SSM 319s showing superior component uniaxial fatigue resistance over cast C355 Fig.8 SSM 319s compressor wheel showing superior durability over cast C355 compressor wheel while comparable with forged 2618 5 Executive summary 1) Turbocharging is one of the most successful technologies to achieve significant emission reduction and fuel economy. About 7% volume increase of turbocharged engines has been achieved in the past 10 years and 8% increase in the next 10 years is predicated. 2) SSM has been successfully applied to produce extremely complex geometric turbocharger compressor wheels. Fig.9 Grains structure of cast C355 (a), forged 2618 (b) and SSM 319s (c), indicating comparable grain size between forged and SSM alloys, while both significant finer than cast alloy 3) SSM compressor wheel has achieved tensile and fatigue properties, and so component durability, approaching forged 2618 and superior over cast C355. 6 Future challenges Although significant progress of manufacturing automotive components by SSM has been achieved and extensive efforts to develop new alloys and processes have been made by researchers, there are still needs for more efforts to satisfy requirements from the industry. These include: 1) More choices of alloys There are different requirements for automotive industrial applications, some need high strength, while some may need high thermal capability, fatigue resistance, corrosion resistance and/or wearing resistance. These need different alloy systems to meet one or more requirements for industrial applications. 2) High melting point alloy systems The greatest efforts of developing SSM processes historically are on alloys with relatively low melting ntsQ. ZHU, et al/Trans. Nonferrous Met. Soc. China 20(2010) s1042-s1047 s1046 points such as aluminum and magnesium alloys. Some efforts and success have been achieved on high melting point alloys such as steels34, but further studies are desirable to develop material systems of cast iron, steels and nickel base alloys. These materials have significant higher density than aluminum and magnesium alloys, so there is greater potential to save more weight of automotive components, and thus more fuel economy, and to improve durability by quality and property improvement in terms of SSM processes than for light alloys. 3) Complex geometric components Complex geometry of some automotive components, such as compressor wheels of a turbocharger and cylinder head in an engine, makes it difficult to achieve the stringent property requirements in cast and efficiency/cost in machining from forged billets. SSM has, therefore, great potential to manufacture complex geometric components. The very low shear strength of alloys at semi-solid status makes it achievable to manufacture complex geometric components when a proper design of runner system and die configuration can be achieved in accommodating the low shear strength but relatively high compressive strength. 4) Cost reduction of current SSM components Cost reduction of manufacturing components has been achieved using SSM process over machining from forged billets. However, due to the high cost of manufacturing raw material bar stock, complexity of runner system and die configuration as well as relatively high process costs, the costs of SSM components are still significantly higher than those of casting. Therefore, efforts should be made to further achieve cost reduction of raw material bar stock, of design and manufacture of runner system and die configuration and of processes. Acknowledgements The authors would express their acknowledgement to Dr. Michael VOONG of Cummins Turbo Technologies Limited for the critical reading and comments of this paper. Thanks also to Andrew P. JACKSON of Aluminum Complex Components Inc. for developing the tooling and general support for successfully manufacturing the SSM impellers. References 1 DASGUPTA R. C/ Proc of 8th Inter Conf on Semi-Solid Processing of Alloys and Composites. Cyprus, 2004. 2 ZHU Q, JACKSON A P. Method and apparatus of Manufacturing Turbine or Compressor WheelsP. WO2007/010181, 2007. 3 LIU D. D. Sheffield: University of Sheffield, 2003. 4 Metal Handbook. Properties and Selection: Nonferrous Alloys and Special Purpose MaterialsM. Vol.2, 10th Ed. Metal Park, OH: ASM, 1990. 5 WABUSSEG H, KAUFMANN H, UGGOWITZER P J. C/ CHIARMETTA G L, ROSSO M. Proc of 6th Inter Conf on Semi-Solid Processing of Alloys and Composites. Turin, Italy, 2000: 777-782. 6 BERGSMA S C, TOLLE M C, EVANGELISTA E. 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