发展非调质的大截面预硬塑料模具钢--外文翻译本科学位论文.doc

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1、 毕业设计(论文)外文资料翻译学 院(系)： 专 业： 姓 名： 学 号： 外文出处： Development of Plastic Mould 附 件： 1.外文资料翻译译文；2.外文原文。 指导教师评语： 签名： 年 月 日注：请将该封面与附件装订成册。附件1：外文资料翻译译文发展非调质的大截面预硬塑料模具钢LUO Yi,WU Xiao-chun,MIN Yong-an,ZHU Zhu,WANG Hong-bin（上海大学材料科学与工程学院，上海200072，中国）摘要：为了满足大截面预硬塑料模具钢的需求和能源节约，一种非调质预硬钢正在发展。一个大型温度场用有限元法研究和9号试验钢在实验室

2、中被设计。对它们的微观结构和硬度调查时用在空气中冷却和控制冷却速度的类似的模拟冷却。结果表明，硬度均匀的截面密切相关与预硬钢的贝氏体淬透性，试验钢的硬度在40到43洛氏硬度之间波动在两种冷却条件下。该试验钢比C45钢具有更加良好的加工性能。预硬钢成功的生产在工厂是基于实验室的结果。它的微观结构是贝氏体，在尺寸为460毫米800毫米3200毫米上均匀分布。关键词：预硬钢；大截面塑料模具；温度估计；化学成分；微观结构；可加工性。生产上的强烈增长和塑料的消耗已经影响了塑料模具钢材市场而对良好性能的塑料模具钢的需求越来越多。各种系列塑料模具钢材适应不同性能要求，例如：耐磨，高硬度，耐腐蚀，韧性，抛光性

3、，纤维化性质，可焊性，可加工性。在现有塑料模具钢材系列中，中低碳合金钢，例如AISI P20中的DIN2738和718（瑞典牌号）长久以来一直被广泛应用着，因为它们的良好的综合性能。P20系列通过调质的形式从钢铁厂的模具生产商生产出来，模具已加工后不需要进行进一步热处理。它通常被称为调质预硬塑料模具钢。预硬塑料模具钢的优势在于模具制造它没有失真的风险，可直接投入运营。然而，调质预硬钢过程复杂和高能源消耗。在规模的塑料行业中，传统的塑料模具QP钢有时可能没有完全淬火或者淬火出现裂纹当它们被用于大的塑料模具时1,2。因此，探讨非调质预硬塑料模具钢为了避免上述的技术和经济缺点3。早在20世纪90年代

4、，150毫米截面的调质预硬塑料模具钢（FT系列）被开发4。在最近十年里，B系列钢诞生和部分代替了低于300毫米截面的P20钢5。 实践表明，该非调质过程也可以生产出具有相似的，统一的硬度比的QP塑料模具钢，同时减少生产周期和耗能。本文主要研究大于300毫米截面的预硬塑料模具钢，特别关注成分设计和满足需求的大截面塑料模具钢1 实验过程在冷却条件上有很大的差别就是小尺寸试验钢生产在实验室里而大截面硬钢生产在工厂，大截面预硬钢将通过微观结构和性能与试验钢比较区别在相似的冷却条件下。实验过程如图1所示。图1. 预硬钢的发展进程9号试验钢被冶炼在250公斤的感应炉里，其化学成分（质量分数，%）显示在表1

5、里。每个试验钢被锻造直径80毫米，然后用两种方式冷却:空气冷却和沙子冷却。切断样品做硬度测试和显微组织观察，尺寸大小为80毫米10毫米。每个样品的硬度与洛氏硬度测定在核心到表面每5毫米处进行，它们的组织在一个尼康LV150光学显微镜下被观察。拉伸样品从在空气冷却中的样品中获得。机械加工性能在切削试验中进行了评估通过测量切削力及切削刀具磨损，分别比较80毫米320毫米的8号试验钢和80毫米310毫米的C45号钢，后者淬火为10%的氯化钠和回火。切削刀具是硬质合金刀具YT15化学成分（质量分数，%）是79WC，15TiC,6Co,它的新优势被用于各项测试中。当进给速度定为0.1mm，切削深度改为0

6、.5mm到0.3mm每0.5mm，主切削力被压电式力测量，切削速度分别在39mmin和78.5mmin,在刀具磨损测定中使用了精度为0.01毫米的工具制造商的显微镜。当进给速度和切削深度固定在0.1mmr和1.5mm时，分别首次消减60分钟的切削速度19.6mmin再消减35分钟的切削速度34mmin在刀具后刀面磨损实验中。表1.测试钢的化学成分2. 讨论和结果2.1 对大断面预硬钢冷却速度的模拟 预硬钢对塑料模具来说期望很大，然而它的冷却速度减慢由于它的尺寸增大。对于大小为460毫米800毫米3200毫米的钢，就必须知道它的温度场，它可以适当的指导淬透性合金设计。简言之，如果核心和表面的空气

7、冷却速度是已知的，以及相应的试验钢的微观的两个冷却速度相似，大断面预硬钢的硬度将分布均匀。在图2上的曲线B和曲线C通过有限元模拟分别反映了再核心和边缘的大致温度。这些估计的冷却速率提供了参考依据为选择合适的淬透性预硬钢。对上述最快最慢的冷却速率物理模拟，当锻造后冷却速率的控制和空气冷却时，钢的测试温度被测量用K型电热偶。测量的温度显示为曲线A和曲线D。由于潜热是没有考虑到有限元模拟，辐射发射表面系数可能会有所不同，在实际的冷却条件下，控制的冷却速率低于被估计的核心的冷却速率。此外，锻压后测试钢在空气中冷却的冷却速率快于表面的估计速率。根据这一点，控制冷却率和空气冷却率的范围比估计的冷却速率大。

8、结合460毫米800毫米3200毫米块的有限元模拟和试验钢的物理模拟，微观结构，核心和表面的特性可以比较控制冷却速率的测试钢和空气冷却的测试钢。图2.测量的冷却曲线和模拟的冷却曲线2.2 化学成分设计当预硬塑料模具钢从模具型腔到制造，其内侧为工作面，这意味着它应该有一个统一的硬度标准。因此，淬透性和整个截面硬度均匀在预硬钢中发挥了重要的作用6。由于传统的预硬钢在淬火冷却的热处理过程中，在一般情况下硬度均匀性与马氏体淬透性密切相关7。然而锻造后，热量与表面的空气转换慢得多比淬火，大截面预硬塑料模具钢很难获得马氏体在整个截面中。但是，如果多边形铁素体转变阻碍贝氏体相变发生在整个截面中，预硬钢硬度可

9、能会略有不同。预硬钢的淬透性在本文中被称为贝氏体淬透性。尽管对于淬火钢来说碳是一个简单又传统的元素，过量的二氧化碳焊接明显有害而且可能影响可加工性。由于这一点，碳含量必须在0.18%到0.31%之间。钼能延缓高温多边形铁素体转化效率而对贝氏体相变的影响不大。特别是“0.5Mo-B”设计在低碳素钢中可以得到充分的贝氏体结构在一个很大的冷却速度范围内8。钼含量在0.1%到0.5%之间应该考虑增加其他合金元素以延缓过冷奥氏体的转变。锰，铬也可以增加来增加淬透性，因为它们可以提供最高的BS温度和最低的MS温度，它们具有良好的焊接性。钒已经被选定为控制奥氏体晶粒长大，它的含量为0.1%。3 工厂试制预硬

10、钢根据8号钢，预硬钢锻造后尺寸为460毫米800毫米3200毫米。硬度测定20毫米沿460毫米和800毫米的方向分开，它徘徊在37到40洛氏硬度之间。贝氏体的显微结构无论是在核心和表面上看，并没有出现大规模的铁氧体，如图3所示。（a）表面 （b）核心图3. 预硬钢的显微结构4 结论核心和表面的冷却速度被估计用有限元模拟和物理模拟在实验室，它提供的数据来选择预硬钢的淬透性。具有良好的贝氏体淬透性钢从实验室中的9号试验钢中选择，它的化学成分是0.27C-1.95M-1.04Cr-0.45Mo-0.1V。它比C45钢具有更好的切削性能9。预硬钢成功的生产在工厂是根据实验室里产生的8号钢为基础的。它的

11、组织是贝氏体，它的硬度在37到40洛氏硬度之间在尺寸为460毫米800毫米3200毫米的模具上。参考文献：1 CHEN Zai-zhi,MA Dang-shen.Plastic Mould Steel Application ManualM.Beijing:The Chemistry Industry Press,2005(in Chinese)2 LUO Yi , WU Xiao-chun. Research Progress of the Work on Prehardened PlasticMould SteelJ.Heat Treatment of Metals,2007,32(12)

12、:22(in Chinese) .3 SONG Dong-li,GU Jian-feng,ZHANG Wei-min,etal.Numerical Simulation onTemperature and Microst ructure DuringQuenching Process for Large-SizedAISI P20 Steel Blocks Used as Plastic DieJ .Transactions of Materialsand Heat Treatment,2004,25(5):740.4 WU Xiao-chun , ZHANGJie , CUI Kun. Th

13、e Microst ructure and Mechanical Properties of Unquenched and Untempered Die Steel for Plastic Mould J . Journal of Huazhong University of Science and Technology ,1995 ,23(12): 1(in Chinese)5 JIANG Lai-zhu ,WANGJiang-hui.Development of a Non-Quenched Non-Tempered Bainitic Steel for Plastic Mould :Co

14、ntinuous Cooling Transformation BehaviorA.J eglit sch F,Ebner R,Leitner H ,eds.Proceedings of the 5th International Conference on ToolingC.Leoben:1999.685.6 SONG Dong-li,GU Jian-feng,PAN Jian-sheng,etal.Design of Quenching Process for Large-Sized AISI P20 Steel Block Used as Plastic DieJ.Journal of

15、Materials Science and Technology,2006,22(1):139.7 LIU Zhuang,WU Zhao-ji,WU Jing-zhi,etal.Numerical Simulation of Heat TreatmentM.Beijing:Science Press,1996(in Chinese).8 Pickering F B. Physical Metallurgy and the Design of SteelsM.London: Applied Science Publishers LTD,1978.9 Vetter P,Hippenstiel F.

16、A New Pre-Hardened Plastic Mould Steel as a Tailored Solution for Large MouldsA.Rosso M,Actis Grande M,Ugues D,eds.Proceedings of the 7th International Conference on Tooling C.Torino:2006.317.附件2：外文原文（复印件）Development of Non-Quenched Prehardened Steel for Large Section Plastic MouldLUO Yi , WU Xiao-c

17、hun ,MIN Yong-an , ZHU Zhu , WAN G Hong-bin(School of Materrial Science and Engineering,Shanghai University,Shanghai 200072,China)Abstract：In order to meet the demand of prehardened steel for large section plast ic mould and save energy,a non quenched prehardenedNQP steel is decelop. The temperature

18、 field of a large block is researched by finite element method simulation and 9 test steels are designed in the laboratory.Their microstructures and hardness are investigated when they are air cooled and control cooled at cooling rate similar to the simulation.The result shows that the hardness unif

19、ormity through section is closely correlated to bainitic hardenability for the NQP steel,and the hardness of steel(0.27C-1.95Mn-1.04Cr-0.45Mo-0.1V) fluctuates between HRC 40 and 43 under both cooling conditions.The test steel has better machinability compared with C45 steel,and the NQP steel is prod

20、uced successfully in the factory based on the laboratory results.Its microstructure is bainite,and it is distrebuted uniformly through the size of 460 mm800 mm3200 mm.Key words : NQP steel ; large section plastic mould ; temperature lestimation ; chemical composition ; microstructure ;machinabilityT

21、he intensive increase in the production and consumption of plastics has also influenced the plastic mould steel market with its demand for increasing amount s and good availability of plastic mould steels. Various serial plastic mould steels are developed to fit the different properties requirements

22、 , e.g1. wear resistance,hardness,corrosion resistance,toughness,polishabilit,texturizing properties , weldability , and machinability.For current plastic mould steel family , the medium carbon low alloyed steel family , such as AISI P 20 and its derived varieties DIN2738 and 718 ( Swedish grade )ha

23、ve long been extensively applied because of their good overall properties. As the P20 family is delivered as quenched and tempered from the steelworks to mould producer and needs no further heat treatment after a mould has been machined , it is usually called quenched and tempered prehardened ( QP )

24、steel for plastic mould 1 ,2 . The advantage of prehardened steel for plastic mould is that the mould made of it does not have the risk of distortion and can be put into operation directly. However , quenched and temperedprehardening has process complexity and high energy consumption. With increasin

25、g dimensions of plastics in the industry , conventional QP steels for plastic mould sometimes may not be full quenched or appear quenching crack when they are used for large section3 . Therefore , non-quenched prehardening is explored in producing plastic mould steel in order to avoid the above-ment

26、ioned technical and economical drawbacks. Early in 1990s , such non-quenched prehardened (NQP) plastic mould steel wit h section of150 mm ( FT series ) was developed4 . In recent years , B series steel was produced and partly instead of P20 steel with section size below 300 mm 5 .Practice shows that

27、 the non-quenching process can also produce plastic mould steel with similar and uniform hardness compared to QP steel , and can simultaneously reduce the production cycle and energy consumption. The present st udy developed an NQP steel for plastic mould with section size larger than 300 mm , speci

28、ally focusing on the composition design , and satisfying the demand of large-section plastic mould steel .1 Experimental ProcedureAs big difference exist s in cooling condition between small size test steels produced in t he laboratory and the large section NQP steel produced in the factory , the NQ

29、P steel should be picked out through microstructure and properties comparison of test steels controlled cooled at similar cooling condition of the large section NQP steel . The experimental procedure is shown in Fig.1.1 Experimental procedureNine test steel swere smelted in a 250 kg induction furnac

30、e , and their chemical compositions (mass percent , %) are shown in Table 2. Each test steel ingot was forged to 80 mm bar , and then cooled in two different ways : air cooled and sand cooled.Samples were cut from bars for the hardness test and microstructure observation , and their size was 80 mm 1

31、0 mm. The hardness of each sample was measured with the Rockwell C hardness tester from it s core to surface every 5 mm , and their microstructures were observed in a Nikon LV150 optical microscope(OM) . Tensile samples were obtained from half radius of air cooled bars.The machinability was evaluate

32、d by measuring the cutting force and wear of the cutting tools in dry turning tests , and the test bars of No.8 steel and C45 steel for comparison were 80 mm 320 mm and80 mm 310 mm , respectively , and the latter was quenched into 10 % NaCl and tempered. The cutting tool was cemented carbide cutter

33、YT15 whose nominal chemical composition (mass percent , %) was 79 WC ,15 TiC , and 6 Co , and its new edge was used in each test . When the feed rate was fixed at 0。1 mm/ r and the cutting depth was changed from 0.5 mm to 3.0 mmevery 0.5 mm , the main cutting force was measured by a piezoelectric fo

34、rce dynamometer at the cutting speed of 39 m/ min and 78.5 m/ min , respectively.The flank wear of tool was measured using a tool makers microscope with precision of 0.01 mm. When the feed rate and the cutting depth were fixed at 0.1mm/ r and 1.5 mm , respectively , two bars were first cut for 60 mi

35、n at the cutting speed of 19.6 m/ min , and then cut for 35 min at the cut ting speed of 34 m/ min in the experiment of the flank wear of tool.Table 1 Chemical composition of test steels2 Results and Discussion2.1 Simulation of the cooling rates of large section NQPThe NQP steel for plastic mould is

36、 expected to be as large as possible , while its cooling rate slows down with its size increasing. For the block with size 460 mm 800 mm 3 200 mm (it is predesigned in the factory) , it is necessary to know it s temperature field , which can guide the alloy design with proper hardenability. Briefly

37、speaking , if the core and surface cooling rate of air cooled block are known , and the corresponding microstructures of the test steel at both cooling rates are similar , the hardness of NQP steel for a large section mould will distribute uniformly.Curve B and curve C in Fig.2 show the estimated te

38、mperature at core and edge in the block separately by FEM simulation. These estimated cooling rates provide the reference data to select the suitable hardenability for the NQP steel. For physically simulating above the slowest and fastest cooling rates ,the temperature of test steels was measured by

39、 the K-type thermocouple when cooled at cont rolled rate and air cooled after forging. The measured temperature is shown as curve A and curve D. As the latent heat is not considered in the FEM simulation , and the radiation emissivity coefficient of surface may vary in the actual cooling condition ,

40、 the controlled coolingrate is slower than that of the estimated cooling rate of the core. Furthermore , the cooling rate of test steels air cooled after forging is faster than that of the surface of the block estimated. According to this , the scope of the controlled cooling rate and the air coolin

41、g rate is wider than that of the estimated cooling rate of the section in the block. Combined FEM simulation of 460 mm800 mm3 200 mm block andphysical simulation of the test steels , microstructures , and properties at core and surface in the block can be compared by controlled cooled test steels an

42、d air cooled ones 2.2Chemical composition design When the prehardened steel for plastic mould is manufactured into the mould cavity , its interior side becomes the working surface , which means it should have a uniform level of hardness. Therefore , hardenability and hardness uniformity throughout t

43、he cross-section play an important part in prehardened steel6 . Since conventional prehardened steel is cooled in quenchant during heat treatment , its hardness uniformity is closely correlated to the martensitic hardenability in several cases7. But for the NQP steel after forging , heat exchange wi

44、th air of its surface is much slower than that with quenchant , and the NQP prehardened steel for large section mould is difficult to obtain martensite through the whole section. However , if only the polygonal ferrite transformation retards and the bainite transformation occurs through the whole se

45、ction , the hardness of the NQP steel may differ slightly. The hardenability for the NQP steel is called bainitic hardenability in this article.Though carbon is an easy and conventional element to harden steel , excessive carbon obviously impairs weldability and may affect the machinability.Owing to

46、 this , the carbon content must be around 0.18 %- 0.30 %. Molybdenum can retard high temperature polygonal ferrite transformation efficiently while have little influence on the bainite transformation. Especially , the“0.5Mo-B”design in the low carbon steel can obtain fully bainitic structures over a

47、 wide range cooling rate8 . The molybdenum content is within 0.1 % - 0.5 % considering the addition of other alloying elements having a similar action to retard the overcooling austenite transformation.Manganese and chromium are also added to increase the hardenability , as they can give maximum depression of Bs temperature and minimum depression ofMs temperature , which is good for the weldability.Vanadium has been chosen to cont rol austenite grain growth , and its content is 0.1 %.3 Factory