热锻模模膛耐热层的材料构成工艺实验研究
详细信息    本馆镜像全文|  推荐本文 |  |   获取CNKI官网全文
摘要
热锻模的寿命问题一直受到业界人士的广泛关注。要提高模具寿命,最重要的是缓解热锻模温度波动区的热应力幅值。本文试图就热锻模模膛表面层区材料进行实验研制和优选,来探索缓解热锻模表面热应力的方法。涉及主要制备方法有等离子喷涂、等离子重熔以及等离子喷焊。
     本文首先总结了热锻模的各种失效形式,以及热锻模寿命和应力的关系,影响热锻模寿命的热物理性能参数;然后介绍了本文涉及到的等离子喷涂、等离子重熔和喷焊技术的研究现状。
     第二部分介绍了实验材料和实验方法。选W6Mo5Cr4V2高速钢为基体;粘结金属和粘结底层材料选用Ni60粉;陶瓷粉未选择了SiC粉,Cr_3C_2粉和WC粉。将Ni60粉和三种碳化物陶瓷粉末分别以70%/30%、80%/20%、90%/10%的比例混合,制成实验所需九种粉。
     然后设计了等离子喷涂-重熔和等离子喷焊实验,基体上喷涂Ni60-SiC涂层,Ni60-Cr3C2涂层,Ni60-WC涂层,再利用等离子弧对喷涂表面进行重熔;同时对另一部分试样采用喷焊法获得喷焊层。最后对等离子喷涂层和“一步法”“两步法”得到的覆层进行比较制定了对涂层进行检测的方案,主要包括采用金相显微分析、显微硬度测定和对主要热物理性能,包括材料的热膨胀系数口热传导系数兄和比热容C进行测定。
     第三部分对检测结果进行纵向对比分析。按陶瓷粉末种类分为三组,对每组中三种配比粉末的喷涂层,重熔层和喷焊层进行比较。
     首先分析了Ni60-SiC试样。从显微结构上,等离子喷涂层呈典型的层状结构,等离子重熔层基体和覆层结合良好,基体对覆层有一定程度的稀释,等离子喷焊层显微组织均匀致密;从显微硬度上进行分析,三种方法中喷焊的硬度最高,喷涂其次,重熔最差。随着SiC含量的增多,涂层的显微硬度增大;三种处理方法中喷焊试样的热物性参数是最好的。等离子喷焊的热膨胀系数和基体最接近,30%SiC试样的热膨胀系数是最小的。结论:30%SiC粉末采用喷焊方法得到的覆层最有利于缓解锻模的热应力。
     接着分析了Ni60-Cr3C2试样。从显微结构上和SiC类似,喷焊层组织均匀致密,是结合最好的;硬度上,喷焊的硬度最高,喷涂其次,重熔最差,随着Cr3C2含量的减少,覆层的显微硬度反而增大;三种处理方法中喷焊试样的热物性参数是最好的。结论:10%Cr3C2粉末采用喷焊方法得到的覆层最有利于缓解锻模的热应力。
     最后对Ni60-WC试样分析。显微结构是喷焊层最好;显微硬度分析表明,三种方法中喷焊的硬度最高,喷涂其次,重熔最差,随着WC含量的增加,覆层的显微硬度增大;三种处理方法中喷焊试样的热物性参数是最好的。结论:30%WC粉末采用喷焊方法得到的覆层最有利于缓解锻模的热应力。
     第四部分在第三部分检测结果的基础上,对30%SiC,10%Cr3C2,30%WC粉末试样进行横向的对比分析。
     从宏观形貌上来说,喷涂层表面粗糙,容易产生裂纹,喷涂厚度因为内应力大而受到制约;重熔层中间有一个烧蚀的凹坑,是重熔时喷枪反复经过中间,加热过度造成的;喷焊层表面光滑致密,厚度达到可2mm,覆层和基体结合良好。从微观形貌上分析,喷涂层是层状结构;重熔层组织细密,基体对覆层有不同程度的稀释,但涂层中没有硬质相;喷焊层覆层和基体形成良好的冶金结合,组织均匀细密,在过渡区形成增碳层或者平面晶带,增大了结合强度。
     在显微硬度方面,喷涂层的硬度和基体相当,但是在过渡区都有一个硬度的下降点;重熔层硬度比基体低,没有达到增大基体硬度的效果;30%WC喷焊层硬度和基体相近,并没有很大的提高,而30%SiC喷焊层和10%Cr3C2喷焊层硬度都远高于基体,达到强化基体硬度的作用。
     在热物性参数的分析中,热膨胀系数是对综合应力最敏感的。30%SiC喷焊层在比热容和热传导上是最满足耐热性要求的。
     在和理论最优粉末质量配比方案匹配方面,10%Cr3C2和理论值相差很大,加上缺少热膨胀系数实验数据,所以不能作为最优配比材料。30%WC喷焊层显微硬度没有达到预期效果,并且配比和理论值相差大,所以不能作为最优配比材料;30%SiC喷焊层实验效果比较好,并且配比和理论值很接近。
     综上所述:本实验中一步法比二步法的效果要好。采用喷焊的方法,选用30%SiC粉末得到的覆层,从宏观形貌,微观形貌,显微硬度和热物性参数上都满足热锻模表面的使用要求。
Life expectancy of hot forging die has been under much concern in the industry. The key solution to increase the life is releasing thermal stress amplitude. In this study, the method to mitigate hot forging die surface thermal stress is discussed, in terms of material testing and optimization of hot forging die surface. Principal preparation method includes plasma spraying, plasma remelting and plasma welding.
     In the first part, failure modes of hot forging die, correlation between life and thermal stress, and parameters that affect the useful life of hot forging die have been brought out. Cutting edge developments of plasma spraying, plasma remelting and plasma welding are also presented.
     In the second part, testing material and method are described. High Speed Steel W6Mo5Cr4V2 is adopted as substrate, bonding metal and bonding base material is Ni60 powder. Ceramic powder is SiC, Cr3C2 and WC. Ni60 and the above mentioned three type of ceramic powder are mixed by the composition of 70%/30%,80%/20%,90%/10%, thus nine composition of powder mixtures are used in the tests.
     Design of plasma spraying-remelting and plasma welding experiment is described thereafter. Firstly, spray Ni60-SiC, Ni60-Cr3C2, Ni60-WC on substrate; Secondly, remelting the plasma spraying layer on plasma arc. At the same time, use plasma overlay welding to obtain plasma spray welding layer. finally, comparing the plasma spraying layer, plasma re-melting layer(called two step method) and plasma spray welding layer (called one step method). The test methods include microscopy, micro-hardness and determine thermal constant which including coefficient of thermal expansion, thermo-conductivity and specific conductance.
     The third part of this article is comparison among the testing results. Each of the three types of Ceramic is mixed by three ratios, and the results of plasma spraying layer, plasma re-melting layer and plasma spray welding layer in each ceramic powder are compared.
     Firstiy, analyzing on Ni60-SiC sample. At metallomicroscopy, the plasma spraying layer is tytical layer structure; in plasma re-melting layer, and overlying strata bond well, we can see overlying strata is dilutioned by; plasma spray welding layer has homogeneous and dense microstructure. At microhardness, comparing three kind of preparation method, plasma spray welding layer has the highest hardness, plasma spraying layer in the middle, plasma re-melting layer has the lowest hardness. Microhardness of layer increases with SiC content increasing. Plasma spray welding sample has the best thermal constant. Coefficient of thermal expansion of plasma spray welding layer is the closest to, and coefficient of thermal expansion of 30%SiC is the lowest. In conclusion, plasma spray welding layer of 30%SiC is the best one to release heat stress amplitude.
     Then, analyzing on Ni60-Cr3C2 sample. It's the same as Ni60-SiC sample at metallomicroscopy. Plasma spray welding layer is the best one because it has homogeneous and dense microstructure. At microhardness, plasma spray welding layer has the highest hardness, plasma spraying layer is in the middle, plasma re-melting layer has the lowest hardness. Microhardness of layer decreases with Cr3C2 content increasing. Plasma spray welding sample has the best thermal constant. In conclusion, plasma spray welding layer of 10%Cr3C2 is the best one to release heat stress amplitude.
     In the end, analyzing on Ni60-WC sample. At metallomicroscopy, plasma spray welding layer is the best one. At microhardness, plasma spray welding layer has the highest hardness, plasma spraying layer is in the middle, plasma re-melting layer has the lowest hardness. Microhardness of layer increases with WC content increasing. Plasma spray welding sample has the best thermal constant. In conclusion,plasma spray welding layer of 30%WC is the best one to release heat stress amplitude.
     The fourth part of this article compared the sample between 30%SiC,10% Cr3C2 and 30%WC, at the base of part three.
     At macroscopic feature, plasma spraying layer has roughening surface and crack easily, and thickness of spray has been restricted by internal stress; plasma re-melting layer has a ablation dent, caused by overheat of spray gun; plasma spray welding layer is smooth and dense, the thickness can achieve 2mm, and overlying strata bond well. At microcosmic feature, plasma spraying layer has layer structure; plasma re-melting layer has homogeneous microstructure, overlying strata is diluted by, lacking hard phase in layer; plasma spray welding layer and overlying strata bond well with plasma spray welding layer, has carbon-enriched layer or plane zone in transition region which can enhance bonding strength.
     At micro-hardness, plasma spraying layer is the same as, but in transition region has a suddenly decent point; plasma re-melting layer is lower than, far away from the target; Plasma spray welding layer of 30%WC is the same as, don't enhance much hardness. Plasma spray welding layers of 30%SiC and 10%Cr3C2 are higher, achieving the effects to improve hardness.
     In thermal constant analyse, coefficient of thermal expansion is sensitive to comprehensive stress. Plasma spray welding layer of 30%SiC can satisfied heat resistance well.
     According to best proportion of powder in theory,10%Cr3C2 and 30%WC can't meet the demand, only 30%SiC can match it.
     In conclusion, one step method is better than two step method; plasma spray welding layer of 30%SiC are more reliable, showing longer life expectancy under operational condition.
引文
[1]王德文.提高模具寿命应用技术实例[M].北京:机械工业出版社,2004:40-41.
    [2]Manas Shirgaokar, M.S. TECHNOLOGY TO IMPROVE COMPETITIVENESS IN WARM AND HOT FORGING-INCREASING DIE LIFE AND MATERIAL UTILIZATION 2008 [C] American:The Ohio State University,2008
    [3]浅谈我国锻压业的差距及发展.网易客,]http://blog.163.com/kzhqy@ 126/blog/static/58346/
    [4]车晓玲.CMF_08_CFF_08力推中国锻压业发展访中国锻压协会副秘书长齐俊河先生[J].金属加工,2008,23:15.
    [5]徐胜利,王波,张玲.提高热锻模寿命的途径-表面强化技术[J].模具制造,2009,3:93.
    [6]王荣滨.热锻模失效分析及强化处理的研究[J].模具制造,2007,3:70.
    [7]喻兴娟.热锻模的失效形式及预防措施[J].机械工艺师,1998(6):9.
    [8]蔡美良,丁惠麟,孟沪龙.新编工模具钢金相热处理[M].北京:机械工业出版社,1998:289-292.
    [9]唐六丁,石玉环,孟瑾,杨茹萍.表面小裂纹热锻模的疲劳寿命[J].河南科技大学学报,2005,5:8.
    [10]Suresh S.材料的疲劳[M].第2版.北京:国防工业出版社,1999:385-388.
    [11]李国平,刘长生.热锻模具的磨损分析[J].中南林学院学报,1996,16:81.
    [12]王华昌,龙满林.锻模综合应力有限元仿真分析[J].模具工业,2004,3:6-10.
    [13]DuerigTW, Melton K N, StockelD, Wayman C M. EngineeringAspects of ShapeMemory Alloys[M]. Lodon:But-terworth-Heinemann,1990:369-393.
    [14]刘靖,温志强.LB510钢热物性参数的实验研究[J].山东冶金,2008,(01)
    [15]郑丽璇,刘建辉,李宁,莫华强.Ni-Ti-Nb合金的热物理性能的测定[J].金属热处理,2005.06:2 1-23.
    [16]张佳秋,姜华,王再江.铸造生产中热物性参数的变化[J].铸造,1998,(08)
    [17]古一,王志法,夏长清.涂层与基底的热膨胀系数差对垂直界面的微裂纹的影响[J].湖南有色金属,2007,03:45-46.
    [18]吴贤官,沈志聪,王塘.涂层的热膨胀系数与附着力[J].上海涂料,2006,(01)
    [19]Chen L, Batra R C. Effect of material parameters on shear band spacing in work-hardening gradient dependent ther-moviscoplastic materials.International Journal of Plasticity,1999, 15:551-574.
    [20]苏铁健,王富耻,李树奎,王鲁.钢的热导率与化学成分和温度的关系[J].兵器材料科学与工程,2004,05
    [21]陈殉.粉煤焦燃烧SCT模型的热重实验研究及其比热容的DSC测定[D].华中科技大学,2008
    [22]丁海涛.纳米薄膜比热容的分子动力学模拟和测试研究[D].大连理工大学,2005
    [23]龚明亮,王华昌,王俊.热锻模材料变物性参数对模具应力影响的模拟分析[J].模具工业,2007,33:59-63.
    [24]王俊,潘清菊,盛志刚等.热锻模材料变物性参数及其变化对温度应力的影响探讨[J].锻压装备与制造技术,2006,33:83-85.
    [25]杨慧.热锻模综合应力与其材料的物理性能参数之间对应关系的有限元分析[D].武汉:武汉理工大学,2005.
    [26]吴人洁.复合材料[M].天津:天津大学出版社,2000:305-309.
    [27]Brinkiene Kristina, Kezelis Romualdas. Correlations between processing parameters and microstructure for YSZ films produced by plasma spray technique[J]. Journal of theEuropean Ceramic Society,2004,24:1095-1099.
    [28]Leigh SH, BerndtC C. Evaluation of off-angle thermal spray[J]. Surface and Coating Technology,1997,89:213-224.
    [29]Sarikaya Ozkan. Effect of the substrate temperature on properties oplasma sprayed Al2O3 coatings[J]. Materials and Design,2005,26:53-57.
    [30]Sarikaya Ozkan.Effect of some parameters onmicrostructure and hardness of alumina coatings prepared by the air plasma spraying process[J]. Surface and CoatingsTechnology,2005, 190:388-393.
    [31]郭锐.FGM等离子喷涂的优化研究[D].长春.长春理工大学材料学,2002.
    [32]王文权.等离子喷涂纳米陶瓷热障涂层组织与性能研究[D].吉林大学,2005
    [33]李宇春,周涛,闵小兵.等离子喷涂法制备梯度结构的金属陶瓷材料[M].2003年纳米和表面科学与技术全国会议(北京)论文摘要集:99.
    [34]Affonso C N, Gonzalo J. Pulsed laster deposition of thin films for optical application.Nuclear Znstruments and Methods in Physics Research.1996, B116:404-409
    [35]王海军,周世魁.超音速等离子喷涂连续梯度热障涂层(CG-TBCs)热震性能研究[J].第十一次全国焊接会议论文集:245
    [36]郑春光.热锻模模膛表面激光熔覆Cr-3C_2耐热层的应用基础研究[D].武汉:武汉理工大学,2008.
    [37]金吴.热锻模模膛表面等离子熔覆SiC耐热层的应用基础研究[D].武汉:武汉理工大学,2009.
    [38]张学秋,宫文彪,刘耀东.激光重熔镍基合金复合涂层组织和性能[J].焊接,2007,(02)
    [39]黄炳华,汤伟杰,王红英.纳米ZrO-2激光重熔涂层组织与性能分析[J].焊接学报,2009,(05)
    [40]王慧萍,戴建强,张光钧,邹昌谷,奚文龙.喷涂与激光重熔技术制备镍基纳米钻包碳化物复合涂层的研究[J].热处理,2007,(03).
    [41]刘其斌,陈佳,王存山,夏元良.宽带激光熔覆铸造WC_p/Ni基合金复合涂层结合界面组织特征[J].贵州工业大学学报(自然科学版),2001,,(01)
    [42]荣鼎慧,刘英才,周拥军,张玉明,丁莉莉.感应重熔Fe-Al金属间化合物涂层的制备及性能研究[J].兵器材料科学与工程,2009,(02)
    [43]Mckamey C QDevan J H,Tortorelli P T,et al.A review of recent developments in Fe3Al-based alloys [J]. Mater Res.1991(6):1779.
    [44]Blackford J R,Buckley R A,Jones H,et al.Spray deposition of iron aluminide[J] J Mater Sci, 1998(33):4417-4421.
    [45]蔚晓嘉,丁路平.不同材质涂层的感应重熔工艺性研究[J].太原重型机械学院学报,1996,(03):53-55.
    [46]吴玉萍,李惠琪,李敏.等离子重熔化学镀Ni-P合金层的溶质分布与相结构[J].材料热处理学报,2001,(02):5 1-54.
    [47]高伟,李艳红,李镇江.Q235钢材表面等离子重熔制备Fe-A1金属间化合物[J].稀有金属快报,2008,(08):32-35.
    [48]潘学民,边秀房,赵程.等离子重熔对A1-16Si合金中Si相的细化作用[J].金属学报,2000,(07):28-29.
    [49]Aoh Jon-ning, Jeng Yau-ren, Chu En-lo, et al.On the wear behavior of surface clad layers under high temperature[J].Wear,1999:1114-1122.
    [50]Aoh Jon-ning, Chen Jian-cheng.On the wear characteris-tics of cobalt-base hardfacing layer after thermal fatigue and oxidation [J].Wear,2001:611-620.
    [51]Kim H J, Kim Y J.Wear and corrosion resistance of PTAweld surfaced Ni and Co base alloy layers[J]. Surface Engi-neering,1999(6):495-501.
    [52]鲍君峰,魏伟.镍基合金粉末等离子弧堆焊层的性能研究[J].有色金属(冶炼部分),2006,(S1):52-54.
    [53]李秉忠.表面工程应用实例[例10]等离子喷焊技术应用于新阀门制造和旧阀门再制造[J].中国表面工程,2009,(03):49-51.
    [54]陈克选,赫晓龙,李春旭.等离子喷焊单片机控制系统研究[J].兰州理工大学学报,2004,(02)
    [55]等离子喷焊在模具制造中的应用[J].模具工业,1982,(04)
    [56]王红英,赵昆,李玉龙,曲维力,董祖珏.送粉形式对等离子粉末堆焊效果的影响[J].焊接,2002,(02):45.
    [57]新野正之,平井敏雄,度边龙三倾斜机能材料[J].日本复合材料杂志,1987,13(6):257-258
    [58]Rodel,Neubrand A.Research program on gradient materials in Germany[A].Functionally Graded Materials 1996[C].Shiata I,Myamoto M Y.etal.Elsevier Science B.V.,1997
    [59]Ilschner B. Lessons Learnt in 7 years of FGM Research at Lausanne[A] [J]. Functionally Graded Materials 1996[C]. Shiota I, Miyamo to M Y, ed., Elsevier Science B. B.,1997: 15-20.
    [60]潘健生,胡明娟.热处理工艺学[M].高等教育出版社,2009:264.
    [60]付劲松.轿车前轮毂闭式热锻模温度场、应力场仿真分析[D].武汉理工大学,2008.
    [62]张国定,赵吕正.金属基复合材料[M].上海:上海交通大学出版社,1993.
    [63]顾德骥.国内外自熔合金粉末表面喷焊技术发展动向[J].机械工程材料,1978,(06):18-19.
    [64]王长生,杨蕴林.WC加入量对Ni60自熔合金喷焊层磨粒磨损性能影响[J].热加工工艺,1997(1):28~30.
    [65]Pang You-xia LuYou-nan (changsha university,changsha,410003, China, Hunan University of Science and Technology, Xiangtan 411201, China). WC喷焊层对Ni60自熔合金冲蚀磨损机理的影响[A].2006全国摩擦学学术会议论文集(三)[C],2006.
    [66]徐滨十,刘世参.中国材料工程大典第八卷无机非金属材料工程(上)[M].化学工业出版社,2007:1 78.
    [67]张雁,刘霓生,陈林泉,等.梯度功能材料物性参数的推定方法[J].固体火箭技 术,2004,1(27):77-79.
    [68]徐滨士,刘世参.中国材料工程大典第八卷无机非金属材料工程(上)[M].化学工业出版社,2007:178.
    [69]李剑锋,黄静琪.等离子喷涂Cr-20-3涂层显微硬度的工艺优化[J].硅酸盐学报,200 1,29(1):49-53

© 2004-2018 中国地质图书馆版权所有 京ICP备05064691号 京公网安备11010802017129号

地址:北京市海淀区学院路29号 邮编:100083

电话:办公室:(+86 10)66554848;文献借阅、咨询服务、科技查新:66554700