激光熔覆成形薄壁试件的工艺和显微组织研究
|
摘要
本文采用实验研究和理论分析相结合的方法对激光熔覆成形薄壁试件工艺和显微组织等方面进行了较深入系统的研究：
1．建立了一套实用的低功率激光熔覆成形实验系统，该系统由1KW连续可调CO_2激光器，三轴坐标数控精密加工机床和粉末输送系统组成，能够实现较高精度薄壁试件的激光熔覆成形。
2．对激光熔覆成形薄壁试件工艺进行了深入研究和分析，首次制得了厚度仅为0.55mm的低碳钢薄壁试件；总结出了不同工艺参数对成形过程中试件宽度的影响规律；将建立的熔池横截面积模型和实验值对比，发现二者表现出一致的变化规律，这为工艺参数的优化和制定提供了理论依据。
3．对激光熔覆成形薄壁试件的精度从实验和理论上进行了研究和分析，发现粉末喷嘴同轴度，光束模式，扫描路径，沿高度方向设定的层高以及送粉稳定性等因素对成形精度有重要影响，上述因素的变化直接影响了熔池形状尺寸及其稳定性，从而降低成形试件精度。
4．对成形后的薄壁低碳钢试件的显微组织进行分析，发现截面沿垂直扫描速度方向组织为细小的等轴晶组成，和目前文献报道的柱状枝晶组织完全不同；结合快速凝固有关理论，分析主要是因为在激光功率低，光斑直径较小等工艺参数条件下，凝固组织形成有利于等轴晶的生长方向所致；而搭接熔覆成形中碳钢组织主要是贝氏体，少量还有魏氏体组织。
5．对成形后的试件进行显微硬度和密度测试，所得结果与传统工艺方法的性能值相当，表明激光熔覆成形工艺能制作出致密度高和性能良好的试件。
The process and microstructure of Laser Cladding Forming (LCF) thin parts are experimentally and theoretically studied in this paper and main conclusions are as follows:
l.A practical LCF equipment, including a 1KW continuous wave CO2 laser instrument, a three-axes CNC processing table and a powder feeding system, was established, by which thin metal components with better accuracy can be built.
2. The process of LCF thin wall has been studied deeply, and a 0.55 mm width thin part with lower carbon steel has been successfully built for the first time; Next, It was investigated systematically that process parameters had an influence on the width of thin wall in deposition; Finally, it was found that the experimental results, in terms of the cross section of molten pool, are in good agreement with that of the theory, which plays an important role in lying out and determining process parameters.
3. The thin wall's accuracy of LCF has also been investigated both experimentally and theoretically, it is presented that coaxial powder-feed nozzle, laser beam mode scanning path have great effects on the accuracy in LCF, for the changes of those factors have direct influences on the shape and stability of melt pool, As a result the accuracy is on the decline.
4. The lower carbon steel thin wall's microstructure of LCF has been carefully analyzed experimentally, and it's microstructure was made up of tiny equiaxed grain, which is entirely different from that of current reports; By combining with theory of fast cooling, the main reason lies in the fact that the solidification microstructure would grow up towards equiaxed grain under lower laser power and smaller laser beam diameter; In addition, the middle carbon part's microstructure of LCF is mainly bainite, a little is wustite structure.
5.Finally, the micro-hardness and density are also examined and experimental results are close to those of traditional processes, it shows that thin parts with near densities and better properties can be fabricated using LCF.
1．建立了一套实用的低功率激光熔覆成形实验系统，该系统由1KW连续可调CO_2激光器，三轴坐标数控精密加工机床和粉末输送系统组成，能够实现较高精度薄壁试件的激光熔覆成形。
2．对激光熔覆成形薄壁试件工艺进行了深入研究和分析，首次制得了厚度仅为0.55mm的低碳钢薄壁试件；总结出了不同工艺参数对成形过程中试件宽度的影响规律；将建立的熔池横截面积模型和实验值对比，发现二者表现出一致的变化规律，这为工艺参数的优化和制定提供了理论依据。
3．对激光熔覆成形薄壁试件的精度从实验和理论上进行了研究和分析，发现粉末喷嘴同轴度，光束模式，扫描路径，沿高度方向设定的层高以及送粉稳定性等因素对成形精度有重要影响，上述因素的变化直接影响了熔池形状尺寸及其稳定性，从而降低成形试件精度。
4．对成形后的薄壁低碳钢试件的显微组织进行分析，发现截面沿垂直扫描速度方向组织为细小的等轴晶组成，和目前文献报道的柱状枝晶组织完全不同；结合快速凝固有关理论，分析主要是因为在激光功率低，光斑直径较小等工艺参数条件下，凝固组织形成有利于等轴晶的生长方向所致；而搭接熔覆成形中碳钢组织主要是贝氏体，少量还有魏氏体组织。
5．对成形后的试件进行显微硬度和密度测试，所得结果与传统工艺方法的性能值相当，表明激光熔覆成形工艺能制作出致密度高和性能良好的试件。
The process and microstructure of Laser Cladding Forming (LCF) thin parts are experimentally and theoretically studied in this paper and main conclusions are as follows:
l.A practical LCF equipment, including a 1KW continuous wave CO2 laser instrument, a three-axes CNC processing table and a powder feeding system, was established, by which thin metal components with better accuracy can be built.
2. The process of LCF thin wall has been studied deeply, and a 0.55 mm width thin part with lower carbon steel has been successfully built for the first time; Next, It was investigated systematically that process parameters had an influence on the width of thin wall in deposition; Finally, it was found that the experimental results, in terms of the cross section of molten pool, are in good agreement with that of the theory, which plays an important role in lying out and determining process parameters.
3. The thin wall's accuracy of LCF has also been investigated both experimentally and theoretically, it is presented that coaxial powder-feed nozzle, laser beam mode scanning path have great effects on the accuracy in LCF, for the changes of those factors have direct influences on the shape and stability of melt pool, As a result the accuracy is on the decline.
4. The lower carbon steel thin wall's microstructure of LCF has been carefully analyzed experimentally, and it's microstructure was made up of tiny equiaxed grain, which is entirely different from that of current reports; By combining with theory of fast cooling, the main reason lies in the fact that the solidification microstructure would grow up towards equiaxed grain under lower laser power and smaller laser beam diameter; In addition, the middle carbon part's microstructure of LCF is mainly bainite, a little is wustite structure.
5.Finally, the micro-hardness and density are also examined and experimental results are close to those of traditional processes, it shows that thin parts with near densities and better properties can be fabricated using LCF.
引文
[1] J.Y. Jeng, S.C. Peng and C.J. Chou. Metal Rapid Prototype Fabrication Using Selective Laser Cladding Technology. Int J Adv Manuf Technol, 2000, 16:681-687
[2] Milewski, JO, Thoma, DJ, Fonseca, JC, and Lewis, GK. Development of a Near Net Shape Processing Method for Rhenium Using Directed Light Fabrication. Journal of Materials and Manufacturing Processes, 1998, 13(5):719-730
[3] M. L. Griffith, D. M. Keicher. Freeform Fabrication of Metallic Components Using Laser Engineered Net Shaping(LENS). In. Proceedings of Solid Freeform Fabrication Symposium, The University of Texas at Austin, Austin, TX, 1996:125-132
[4] William Hofmeister, Michelle Griffith, Mark Ensz, John Smugeresky. Solidification in Direct Metal Deposition by LENS Processing. JOM, 2001, 53(9): 30-34
[5] CL Atwood, ML Griffith, M E. Schlienger, LD Harwell, MT Ensz, DM Keicher, ME Schlienger, JA Romero, JE Smugeresky. Laser Engineered Net Shaping (LENS~(TM)):A Tool for Direct Fabrication of Metal Parts. In Proceedings of ICALEO '98, November 16-19, 1998, Orlando, FL: E-1
[6] M. L. Griffith, M. T. Ensz, J. D. Puskar, Laser Engineered Net Shaping Manufacturing Technologies. http://mfgshop.sandia.gov/1400_ext/LENS.pdf
[7] 刘继常．激光熔覆直接成形金属铸造模具的探讨．制造技术与机床，2003，(5)：44-46
[8] Elshof, H.L.F.. Heat Fluxes Between Semi-Infinite Solids. Graduate Thesis, Un. of Twente, Dept. of Mech. Eng., 1994
[9] Franz-Josef Kahlen, Aravinda Kar. Tensile Strengths for Laser-Fabricated Parts and Similarity Parameters for Rapid Manufacturing. Transactions of the ASME, 2001, 123:38-44
[10] Aditad Vasinonta, Jack L.Beuth, Michelle L.Griffith. A Process Map for Consistent Build Conditions in the Solid Freeform Fabrication of Thin-Walled Structures. Journal of Manufacturing Science and Engineering, 2001,123:615-622
[11] J.P.Kruth, M.C.Leu and T.Nakagawa. Progress in Additive Manufacturing and Rapid Prototyping. Annals of the CIRP, 1998,47(2): 525-540
[12] M. L. Griffith, M. T. Ensz, J. D. Puskar, C. V. Robino, J. A. Brooks, J. A. Philliber, J. E. Smugeresky, W. H. Hofmeister. Understanding the Microstructure and Properties of Components Fabricated by Laser Engineered Net Shaping (LENS). mfgshop.sandia.gov/1400_ext/MRS00mg.pdf
[13] F G Arcella. F H Froes. Producing titanium aerospace components using laser forming. Journal of Metals, 2000, 52(5): 28-30
[14] M. L. Griffith. Laser Engineered Net Shaping (LENS). http://63.238.76.66/lens.htm
[15] Kenneth C. Meinert, Jr., Eric J. Whitney, Paul A. Blomquist. Laser Cladding for the U.S. Navy REPTECH Program. Institu ufacturing and Sustainment Technologies, 2000 No.4:3-5te for Man
[16] F.G. Arcella, D.H. Abbott, M.A. House. Titanium Alloy Structures for Airframe Application, by the Laser Forming Process. In the 41st AIAA Structures, Structural Dynamics & Materials Conference, AeroMet Corporation, 2000:1465-1473
[17] Hybrid fabrication process: machining+LENS. MFG S&T Quarterly, 2003, 1(3): 2 http://mfgshop.sandia.gov/1400_ext/2003MayMFGSTNews.pdf
[18] D.B. Snow, E.M. Breinan,B.H. Kear. Rapid solidification processing of superalloy using high power lasers, Superalloys. In Proceedings Fourth International Symposium, Alaitors Publishing Div., Baton Rouge, LA, 1980, 189-203
[19] Koch, J.L. and Mazumder, J.. Rapid Prototyping by Laser Cladding. The International Society for Optical Engineering, 1993, 2306, p556-565
[20] M. Murphy, C. Lee, W. M. Steen. Studies in Rapid Prototyping by Laser Surface Cladding. Surf Coat Technol, 1991,49(1): 40-45
[21] Stuart F. Brown. How Hot Lasers are Taming Titanium. Fortune Magazine, Industrial Management & Technology Section, 2000, 141(4): 240
[22] 张永忠等．激光快速成形316L不锈钢研究．材料工程，2002(5)22—25
[23] Abbott, DH and Arcella, FG. Laser Forming Titanium Components. Advanced Materials and Processes, 1998, 153(5): 29-31
[24] Simon Pickering. AeroMet implementing novel Ti process. Metal Powder Report, 1998, 53(2): 24-26
[25] M. L. Griffith, L. D. Harwell, J. A. Romero, E. Schlienger, C. L. Atwood, J. E. Smugeresky. Multi-Material Processing by LENS. In Proceedings of the Solid Freeform Fabrication Symposium, Austin, TX, 1997, p.387
[26] D B Snow, E M Breinan, B H Kear, Rapid solidification processing of superalloy using high power lasers, Superalloys, Proceedings Fourth International Symposium, A laitors Publishing Div.,Baton Rouge, LA, 1980:189-203
[27] CLA twood, M L Griffith, L D Harwell, et al. Laser spray fabrication for net-shape rapid product realization LDRD. Sandia Raeport, 1999
[28] J L. Koch J.mazumder, Rapid prototyping by laser cladding, ICALEO,Orlando FL,1993:556-565
[29] Murphy M, Lee C, Steen W M. Studies in rapid prototyping by laser surface cladding. ICALEO, 1993:882
[30] 杨海欧．Ren95合金激光立体成形显微组织与力学性能的研究：[西北工业大学硕士学位论文]．西安：西北工业大学材料科学与工程学院，2002，10-11
[31] M. Labudovic, D. Hu, R. Kovacevic. A three dimensional model for direct laser metal powder deposition and rapid prototyping. Journal of Materials Science, 2003, 38: 35-49
[32] H. S, Carslaw and J. C. Jaeger. Conduction of Heat in Solids. Clarendon Press, Oxford, UK, 1959:134
[33] J. A. Greenwood, An Interpolation Formula for Flash Temperatures. Wear, 1991, 150:153-158
[34] M. Bass. In Proceedings of the Conference on Laser-Materials Interactions, San Diego, July 1988, edited by T. Brown, Academic Press, New York, 1998:122
[35] M.F. Schneider. Laser Cladding With Powder. Ph.D. Thesis, University of Twente,Enschede,TheNetherlands.March 1998.www.ub.utwente. nl/webdocs/wb/1/t 0000007.pdf;
[36] 曾大文，谢长生．激光熔覆温度场和流场数值模拟研究现状和发展趋势．材料科学与工程，1997，15(4)：1-8，50
[37] 刘振侠，黄卫东，万柏涛．送粉式激光熔覆数值模型基本问题研究．中国激光，2003，(6)
[38] 曾大文，谢长生．激光熔覆二维准稳态流场及温度场的数值模拟．金属学报，1999，35(6)：604-610
[39] S. Sarkar, P. Mohan Raj, S. Chakraborty, G. Phanikumar, K. Chattopadhyay, P. Dutta. Transport phenomena in laser surface alloying. Journal of Materials Science, 2003.38:155-164
[40] 曾大文，谢长生．激光熔池三维非稳态对流传热过程的数值模拟．激光技术，2002，26(2)：102-105
[41] 邹德宁，雷永平，黄廷禄，苏俊义．移动热源条件下熔池内流体流动和传热问题的数值研究．金属学报，2000，(4)：387-390
[42] Jehnming Lin and Bor-Chyang Hwang. Coaxial laser cladding on an inclined substrate. Optics & Laser Technology, 1999, 31:571-578
[43] Steen, W.M., Weerasinghe, V.M., and Monson, P.. Some Aspects of the Formation of Laser Clad Tracks. SPIE, 1986, 650:226-234
[44] Hu, Y.P., Chen, C.W, and Mukherjee, K. Innovative Laser-Aided Manufacturing of Patterned Stamping and Cutting Dies: Processing Parameters. Materials and
Manufacturing Processes, 1998, 13(3): 369-387
[45] Mazumder J., Schifferer A., and Choi J..Direct Materials Deposition: Designed Macro and Microstructure. Materials Research Innovations, 1999, 3(3): 118-131
[46] 张庆茂，王忠东，刘喜明等．工艺参数对送粉激光熔覆层几何形貌的影响．焊接学报，2000，21(2)：44-46
[47] F.W.Liou, J.Choi, R.G.Landers, V.Janardhanan, S.N.Balakrishnan, S.Agarwal. Research and Development of a Hybrid Rapid Manufacturing Process. Proceedings of the Solid Freeform Fabrication Symposium, 2001, pp138-145. web.umr.edu/～landersr/PAPERS/SFF01 a.pdf
[48] David Abbott, Frank Arcella, Laser forming titanium components, Advanced Materials & Processes. May 1998.29-30
[49] Jehnming Lin, Bor-Chyang Hwang, Coaxial laser cladding on an inclined substrate, Optics& Laser Tech, Vol.31, 1999, 571-578
[50] Lin J, Steen WM, Design characteristics and development of a nozzle for coaxial cladding, J. Laser Appl.Vol, 10, 1998, 55-63
[51] J. Mazumder, K. Nagarathnam, J.Choi, J. Koch, D. Hetzner. The Direct Metal Deposition of H13 Tool Steel for 3-D Components. JOM, 49(5), 1997:55-60
[52] Gayle Link. Layered manufacturing of laser deposited carbon steels. Ph.D. Thesis, Stanford University.www.-rpl.stanford.edu/files/thesis/glink.pdf,September 1999
[53] M. L. Griffith, M. T. Ensz, J. D. Puskar, C. V. Robino, J. A. Brooks, J. A. Philliber, J. E. Smugeresky, W. H. Hofmeister. Understanding the Microstructure and Properties of Components Fabricated by Laser Engineered Net Shaping (LENS). mfgshop.sandia.gov/1400_ext/MRS00mg.pdf
[54] 马琨．激光熔化热处理的理论及实验研究．激光杂志，2004，(25)1：23-25
[55] 席明哲．扫描速度对激光快速成型316L不锈钢组织性能的影响．稀有金属，2002(3)93—97
[56] 李力钧．现代激光加工及其装备．北京：北京理工大学出版社，1993．
[57] M.F. SCHNEIDER, in Ph.D. thesis, University of Twente, Enschede, Netherlands, 1998, p104
[58] 李俊昌．激光的衍射及热作用计算．北京：科学出版社，2002
[59] F.EINCROPERA and D.P.DE WITT, in "Fundamentals of Heat and Mass Transfer" (Wiley, Chichester, 1974) p120
[60] 李延民．激光多层涂覆过程中的温度场测量与数值模拟．金属学报2003(5)521—525
[61] 李延民．激光立体成形工艺特性与显微组织研究：[西北工业大学博士学位论
文]．西安：西北工业大学材料科学与工程学院，2001，78-79
[62] 周尧和等．凝固技术．北京：机械工业出版社，1998
[63] 王开富．金属陶瓷激光熔覆处理的工艺参数和组织性能优化．兰州大学学报，1996，32(4)：50—54
[64] J.D. Hunt. Steady state columnar and equiaxed growth of dendrites and eutectic, Mater. Sci. and Eng., Vol.65,1984, 75-83
[65] Iuliano Luca, Settineri Luca, Gatto Andrea.ProcPRICM3 [C].USA: The Minerals, Metals&MaterialsSociety, 1998:1631—1636
[66] Fritz B P and Lee E W, Novel applications and Implementations of Shape Deposition Manufacturing, ICRPM98, 1998; 20-29
[2] Milewski, JO, Thoma, DJ, Fonseca, JC, and Lewis, GK. Development of a Near Net Shape Processing Method for Rhenium Using Directed Light Fabrication. Journal of Materials and Manufacturing Processes, 1998, 13(5):719-730
[3] M. L. Griffith, D. M. Keicher. Freeform Fabrication of Metallic Components Using Laser Engineered Net Shaping(LENS). In. Proceedings of Solid Freeform Fabrication Symposium, The University of Texas at Austin, Austin, TX, 1996:125-132
[4] William Hofmeister, Michelle Griffith, Mark Ensz, John Smugeresky. Solidification in Direct Metal Deposition by LENS Processing. JOM, 2001, 53(9): 30-34
[5] CL Atwood, ML Griffith, M E. Schlienger, LD Harwell, MT Ensz, DM Keicher, ME Schlienger, JA Romero, JE Smugeresky. Laser Engineered Net Shaping (LENS~(TM)):A Tool for Direct Fabrication of Metal Parts. In Proceedings of ICALEO '98, November 16-19, 1998, Orlando, FL: E-1
[6] M. L. Griffith, M. T. Ensz, J. D. Puskar, Laser Engineered Net Shaping Manufacturing Technologies. http://mfgshop.sandia.gov/1400_ext/LENS.pdf
[7] 刘继常．激光熔覆直接成形金属铸造模具的探讨．制造技术与机床，2003，(5)：44-46
[8] Elshof, H.L.F.. Heat Fluxes Between Semi-Infinite Solids. Graduate Thesis, Un. of Twente, Dept. of Mech. Eng., 1994
[9] Franz-Josef Kahlen, Aravinda Kar. Tensile Strengths for Laser-Fabricated Parts and Similarity Parameters for Rapid Manufacturing. Transactions of the ASME, 2001, 123:38-44
[10] Aditad Vasinonta, Jack L.Beuth, Michelle L.Griffith. A Process Map for Consistent Build Conditions in the Solid Freeform Fabrication of Thin-Walled Structures. Journal of Manufacturing Science and Engineering, 2001,123:615-622
[11] J.P.Kruth, M.C.Leu and T.Nakagawa. Progress in Additive Manufacturing and Rapid Prototyping. Annals of the CIRP, 1998,47(2): 525-540
[12] M. L. Griffith, M. T. Ensz, J. D. Puskar, C. V. Robino, J. A. Brooks, J. A. Philliber, J. E. Smugeresky, W. H. Hofmeister. Understanding the Microstructure and Properties of Components Fabricated by Laser Engineered Net Shaping (LENS). mfgshop.sandia.gov/1400_ext/MRS00mg.pdf
[13] F G Arcella. F H Froes. Producing titanium aerospace components using laser forming. Journal of Metals, 2000, 52(5): 28-30
[14] M. L. Griffith. Laser Engineered Net Shaping (LENS). http://63.238.76.66/lens.htm
[15] Kenneth C. Meinert, Jr., Eric J. Whitney, Paul A. Blomquist. Laser Cladding for the U.S. Navy REPTECH Program. Institu ufacturing and Sustainment Technologies, 2000 No.4:3-5te for Man
[16] F.G. Arcella, D.H. Abbott, M.A. House. Titanium Alloy Structures for Airframe Application, by the Laser Forming Process. In the 41st AIAA Structures, Structural Dynamics & Materials Conference, AeroMet Corporation, 2000:1465-1473
[17] Hybrid fabrication process: machining+LENS. MFG S&T Quarterly, 2003, 1(3): 2 http://mfgshop.sandia.gov/1400_ext/2003MayMFGSTNews.pdf
[18] D.B. Snow, E.M. Breinan,B.H. Kear. Rapid solidification processing of superalloy using high power lasers, Superalloys. In Proceedings Fourth International Symposium, Alaitors Publishing Div., Baton Rouge, LA, 1980, 189-203
[19] Koch, J.L. and Mazumder, J.. Rapid Prototyping by Laser Cladding. The International Society for Optical Engineering, 1993, 2306, p556-565
[20] M. Murphy, C. Lee, W. M. Steen. Studies in Rapid Prototyping by Laser Surface Cladding. Surf Coat Technol, 1991,49(1): 40-45
[21] Stuart F. Brown. How Hot Lasers are Taming Titanium. Fortune Magazine, Industrial Management & Technology Section, 2000, 141(4): 240
[22] 张永忠等．激光快速成形316L不锈钢研究．材料工程，2002(5)22—25
[23] Abbott, DH and Arcella, FG. Laser Forming Titanium Components. Advanced Materials and Processes, 1998, 153(5): 29-31
[24] Simon Pickering. AeroMet implementing novel Ti process. Metal Powder Report, 1998, 53(2): 24-26
[25] M. L. Griffith, L. D. Harwell, J. A. Romero, E. Schlienger, C. L. Atwood, J. E. Smugeresky. Multi-Material Processing by LENS. In Proceedings of the Solid Freeform Fabrication Symposium, Austin, TX, 1997, p.387
[26] D B Snow, E M Breinan, B H Kear, Rapid solidification processing of superalloy using high power lasers, Superalloys, Proceedings Fourth International Symposium, A laitors Publishing Div.,Baton Rouge, LA, 1980:189-203
[27] CLA twood, M L Griffith, L D Harwell, et al. Laser spray fabrication for net-shape rapid product realization LDRD. Sandia Raeport, 1999
[28] J L. Koch J.mazumder, Rapid prototyping by laser cladding, ICALEO,Orlando FL,1993:556-565
[29] Murphy M, Lee C, Steen W M. Studies in rapid prototyping by laser surface cladding. ICALEO, 1993:882
[30] 杨海欧．Ren95合金激光立体成形显微组织与力学性能的研究：[西北工业大学硕士学位论文]．西安：西北工业大学材料科学与工程学院，2002，10-11
[31] M. Labudovic, D. Hu, R. Kovacevic. A three dimensional model for direct laser metal powder deposition and rapid prototyping. Journal of Materials Science, 2003, 38: 35-49
[32] H. S, Carslaw and J. C. Jaeger. Conduction of Heat in Solids. Clarendon Press, Oxford, UK, 1959:134
[33] J. A. Greenwood, An Interpolation Formula for Flash Temperatures. Wear, 1991, 150:153-158
[34] M. Bass. In Proceedings of the Conference on Laser-Materials Interactions, San Diego, July 1988, edited by T. Brown, Academic Press, New York, 1998:122
[35] M.F. Schneider. Laser Cladding With Powder. Ph.D. Thesis, University of Twente,Enschede,TheNetherlands.March 1998.www.ub.utwente. nl/webdocs/wb/1/t 0000007.pdf;
[36] 曾大文，谢长生．激光熔覆温度场和流场数值模拟研究现状和发展趋势．材料科学与工程，1997，15(4)：1-8，50
[37] 刘振侠，黄卫东，万柏涛．送粉式激光熔覆数值模型基本问题研究．中国激光，2003，(6)
[38] 曾大文，谢长生．激光熔覆二维准稳态流场及温度场的数值模拟．金属学报，1999，35(6)：604-610
[39] S. Sarkar, P. Mohan Raj, S. Chakraborty, G. Phanikumar, K. Chattopadhyay, P. Dutta. Transport phenomena in laser surface alloying. Journal of Materials Science, 2003.38:155-164
[40] 曾大文，谢长生．激光熔池三维非稳态对流传热过程的数值模拟．激光技术，2002，26(2)：102-105
[41] 邹德宁，雷永平，黄廷禄，苏俊义．移动热源条件下熔池内流体流动和传热问题的数值研究．金属学报，2000，(4)：387-390
[42] Jehnming Lin and Bor-Chyang Hwang. Coaxial laser cladding on an inclined substrate. Optics & Laser Technology, 1999, 31:571-578
[43] Steen, W.M., Weerasinghe, V.M., and Monson, P.. Some Aspects of the Formation of Laser Clad Tracks. SPIE, 1986, 650:226-234
[44] Hu, Y.P., Chen, C.W, and Mukherjee, K. Innovative Laser-Aided Manufacturing of Patterned Stamping and Cutting Dies: Processing Parameters. Materials and
Manufacturing Processes, 1998, 13(3): 369-387
[45] Mazumder J., Schifferer A., and Choi J..Direct Materials Deposition: Designed Macro and Microstructure. Materials Research Innovations, 1999, 3(3): 118-131
[46] 张庆茂，王忠东，刘喜明等．工艺参数对送粉激光熔覆层几何形貌的影响．焊接学报，2000，21(2)：44-46
[47] F.W.Liou, J.Choi, R.G.Landers, V.Janardhanan, S.N.Balakrishnan, S.Agarwal. Research and Development of a Hybrid Rapid Manufacturing Process. Proceedings of the Solid Freeform Fabrication Symposium, 2001, pp138-145. web.umr.edu/～landersr/PAPERS/SFF01 a.pdf
[48] David Abbott, Frank Arcella, Laser forming titanium components, Advanced Materials & Processes. May 1998.29-30
[49] Jehnming Lin, Bor-Chyang Hwang, Coaxial laser cladding on an inclined substrate, Optics& Laser Tech, Vol.31, 1999, 571-578
[50] Lin J, Steen WM, Design characteristics and development of a nozzle for coaxial cladding, J. Laser Appl.Vol, 10, 1998, 55-63
[51] J. Mazumder, K. Nagarathnam, J.Choi, J. Koch, D. Hetzner. The Direct Metal Deposition of H13 Tool Steel for 3-D Components. JOM, 49(5), 1997:55-60
[52] Gayle Link. Layered manufacturing of laser deposited carbon steels. Ph.D. Thesis, Stanford University.www.-rpl.stanford.edu/files/thesis/glink.pdf,September 1999
[53] M. L. Griffith, M. T. Ensz, J. D. Puskar, C. V. Robino, J. A. Brooks, J. A. Philliber, J. E. Smugeresky, W. H. Hofmeister. Understanding the Microstructure and Properties of Components Fabricated by Laser Engineered Net Shaping (LENS). mfgshop.sandia.gov/1400_ext/MRS00mg.pdf
[54] 马琨．激光熔化热处理的理论及实验研究．激光杂志，2004，(25)1：23-25
[55] 席明哲．扫描速度对激光快速成型316L不锈钢组织性能的影响．稀有金属，2002(3)93—97
[56] 李力钧．现代激光加工及其装备．北京：北京理工大学出版社，1993．
[57] M.F. SCHNEIDER, in Ph.D. thesis, University of Twente, Enschede, Netherlands, 1998, p104
[58] 李俊昌．激光的衍射及热作用计算．北京：科学出版社，2002
[59] F.EINCROPERA and D.P.DE WITT, in "Fundamentals of Heat and Mass Transfer" (Wiley, Chichester, 1974) p120
[60] 李延民．激光多层涂覆过程中的温度场测量与数值模拟．金属学报2003(5)521—525
[61] 李延民．激光立体成形工艺特性与显微组织研究：[西北工业大学博士学位论
文]．西安：西北工业大学材料科学与工程学院，2001，78-79
[62] 周尧和等．凝固技术．北京：机械工业出版社，1998
[63] 王开富．金属陶瓷激光熔覆处理的工艺参数和组织性能优化．兰州大学学报，1996，32(4)：50—54
[64] J.D. Hunt. Steady state columnar and equiaxed growth of dendrites and eutectic, Mater. Sci. and Eng., Vol.65,1984, 75-83
[65] Iuliano Luca, Settineri Luca, Gatto Andrea.ProcPRICM3 [C].USA: The Minerals, Metals&MaterialsSociety, 1998:1631—1636
[66] Fritz B P and Lee E W, Novel applications and Implementations of Shape Deposition Manufacturing, ICRPM98, 1998; 20-29