铝合金激光熔敷流场和温度场的数值模拟
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摘要
由于密度低、强度高、塑性好等优点,铝及铝合金广泛应用于航空、汽车和运输等行业。但硬度低和耐磨性差等缺点限制了其应用的进一步推广。激光熔敷技术是一种具有良好应用前景的表面处理技术,能够提高铝合金表面性能。对激光熔池流场和温度场定量的分析对于预测和控制表面硬化层质量具有重要的理论意义和现实意义。
在回顾了激光熔敷温度场和流场数值模拟研究的发展历史和综述了铝合金激光熔敷的研究现状后,本文进行了铝合金激光熔敷实验,得到了与基体形成良好冶金结合的熔敷层。经实测,熔敷层硬度明显高于基体材料。
论文重点研究了基于通用有限元软件ANSYS的铝合金激光熔敷温度场和流场的耦合模拟。采用“固液同一法”简化了固液边界推移的模拟;通过在气液边界施加等效体力的方法,实现了对Marangoni对流的模拟;文章还实现了多种材料混合的熔敷过程温度场和流场的模拟。模拟结论与实际激光熔敷相比,在一定程度上相近。本文还讨论了激光工艺参数对激光熔池形貌、流场分布和温度场分布的影响。
研究发现:增大激光功率将扩大熔池尺寸,提高工件温度,加速熔池流体流动;提高扫描速度将缩小熔池尺寸,降低工件温度,减缓熔池流体流动;扩大光斑直径,熔池尺寸总体上减小,但光斑直径对工件整体的温度分布影响不大,只在近熔池区,随着光斑直径的扩大,温度有所降低,但光斑直径对熔池内流体的流动影响明显,光斑越大,熔池内流体流速越小。
论文最后进行了多道次搭接激光熔敷的数值模拟,运用APDL语言成功的控制了激光热源的多道次往复运动。简要分析了后熔敷温度场分布对先熔敷层的影响。
Due to its low density, high specific strength, good plasticity etc, Aluminum and its alloy are widely applied in many fields, like aerospace, auto industries and transportation and so on. But its poor surface performance including poor corrosion resistance and wear resistance restrict its wider application in the modern industries. Laser cladding can improve the surface properties of aluminum alloy, which is a surface treatment technology with good prospect. It can improve the surface properties of aluminum alloy. Quantitative analysis for fluid field, temperature field in laser melting pool has important theoretical and practical significance for predicting and controlling quality of harden surface.
In this paper, the history of simulation for the temperature and velocity distribution in the laser cladding melting pool was reviewed. Then a summery of the laser cladding on Aluminum was presented. And, the Al-Y-Ni alloys coatings were prepared on Al-based alloy by laser cladding. The experiments indicate that the coatings have smooth and continuous surface, and metallurgical bond to the substrate. The cladding elements exist in the bottom of the cladding layer, which means the element was transfer by some strong fluid flow. The average hardness of cladding layer is higher than the substrate.
This paper focused on the numerical coupling simulation of the fluid flow and heat transfer in the laser cladding melting pool based on the popular FEA software ANSYS. The movement of the solid-liquid interface was simulated in the method which was setting the temperature dependant fluid viscosity. Under the melting point of the aluminum alloy the viscosity of the flow was set as an extraordinary huge value. And the viscosity of the fluid was made as the real value after the metal was fused. The Marangoni convection was carried out by applied an equivalent continuous body force on nodes in the liquid-gas interface. The problem of the simulation on multi-species cladding system was also solved. The analysis result coincided with the actual laser cladding to some degree.
The paper also analyzed the influence of the laser processing parameter on the melting pool shape, temperature distribution and the fluid flow field, drawing the conclusion that was the radius and depth of the melting pool increased along with the laser power rising and the decreasing of the scanning velocity.
In the end, the overlapping laser cladding was simulated. The movement of the laser heat source was realized by the APDL.
在回顾了激光熔敷温度场和流场数值模拟研究的发展历史和综述了铝合金激光熔敷的研究现状后,本文进行了铝合金激光熔敷实验,得到了与基体形成良好冶金结合的熔敷层。经实测,熔敷层硬度明显高于基体材料。
论文重点研究了基于通用有限元软件ANSYS的铝合金激光熔敷温度场和流场的耦合模拟。采用“固液同一法”简化了固液边界推移的模拟;通过在气液边界施加等效体力的方法,实现了对Marangoni对流的模拟;文章还实现了多种材料混合的熔敷过程温度场和流场的模拟。模拟结论与实际激光熔敷相比,在一定程度上相近。本文还讨论了激光工艺参数对激光熔池形貌、流场分布和温度场分布的影响。
研究发现:增大激光功率将扩大熔池尺寸,提高工件温度,加速熔池流体流动;提高扫描速度将缩小熔池尺寸,降低工件温度,减缓熔池流体流动;扩大光斑直径,熔池尺寸总体上减小,但光斑直径对工件整体的温度分布影响不大,只在近熔池区,随着光斑直径的扩大,温度有所降低,但光斑直径对熔池内流体的流动影响明显,光斑越大,熔池内流体流速越小。
论文最后进行了多道次搭接激光熔敷的数值模拟,运用APDL语言成功的控制了激光热源的多道次往复运动。简要分析了后熔敷温度场分布对先熔敷层的影响。
Due to its low density, high specific strength, good plasticity etc, Aluminum and its alloy are widely applied in many fields, like aerospace, auto industries and transportation and so on. But its poor surface performance including poor corrosion resistance and wear resistance restrict its wider application in the modern industries. Laser cladding can improve the surface properties of aluminum alloy, which is a surface treatment technology with good prospect. It can improve the surface properties of aluminum alloy. Quantitative analysis for fluid field, temperature field in laser melting pool has important theoretical and practical significance for predicting and controlling quality of harden surface.
In this paper, the history of simulation for the temperature and velocity distribution in the laser cladding melting pool was reviewed. Then a summery of the laser cladding on Aluminum was presented. And, the Al-Y-Ni alloys coatings were prepared on Al-based alloy by laser cladding. The experiments indicate that the coatings have smooth and continuous surface, and metallurgical bond to the substrate. The cladding elements exist in the bottom of the cladding layer, which means the element was transfer by some strong fluid flow. The average hardness of cladding layer is higher than the substrate.
This paper focused on the numerical coupling simulation of the fluid flow and heat transfer in the laser cladding melting pool based on the popular FEA software ANSYS. The movement of the solid-liquid interface was simulated in the method which was setting the temperature dependant fluid viscosity. Under the melting point of the aluminum alloy the viscosity of the flow was set as an extraordinary huge value. And the viscosity of the fluid was made as the real value after the metal was fused. The Marangoni convection was carried out by applied an equivalent continuous body force on nodes in the liquid-gas interface. The problem of the simulation on multi-species cladding system was also solved. The analysis result coincided with the actual laser cladding to some degree.
The paper also analyzed the influence of the laser processing parameter on the melting pool shape, temperature distribution and the fluid flow field, drawing the conclusion that was the radius and depth of the melting pool increased along with the laser power rising and the decreasing of the scanning velocity.
In the end, the overlapping laser cladding was simulated. The movement of the laser heat source was realized by the APDL.
引文
[1]李俊昌.激光的衍射及热作用计算.第一版.北京:科学出版社,2002.67~69
[2]曾大文,谢长生.激光熔敷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
[3] S. Kou, D. K. Sun. Fluid flow and Penetration in stationary Arc Welds, Metall. Trans., 1985, (17A), 203~204
[4] T. Zacharia et al., Modeling of Non-autogenous welding-Model Predicts Three dimensional Convection and Temperature Conditions of the Weld Pool Generated by a Moving Arc, Welding Journal, 1988, 67(1), 18~19
[5] A. F. A. Hoadley et al., Heat Flow Simulation of Laser Remelting with Experimental Validation, Metall. Trans. B, 1991, 22B(2), 101~105
[6] T. Zacharia et al., Modeling of Non-autogenous welding-Model Predicts Three dimensional Convection and Temperature Conditions of the Weld Pool Generated by a Moving Arc, Welding Journal, 1988, 67(3), 53~58
[7] M. C. Tsai, S. Kou. Weld Pool Convection and Expansion due to Density Variations Treatment, Numerical Heat Transfer, 1990, 17(3), 73~77
[8]曹振宁. TIG/MIG焊接熔透熔池流场与热场的研究:[博士学位论文]。保存地点:哈尔滨工业大学图书馆,1993.
[9] A. F. A. Hoadley, M.Rappaz, A Thermal Model of Laser Cladding by Power Injection, Metall. Trans. B, 1992, 23B(10), 631~640
[10]曾大文.激光熔池流场温度场与浓度场的数值分分析:[博士学位论文]。保存地点:华中科技大学图书馆,1998.
[11] T. T. Anthony and H.E. Cline, Surface Rippling Induced by Surface Tension Gradients during Laser Surface Melting and Alloying, Journal of Applied Physics, 1997,48(9):281~285
[12] P. Sahoo et al., Surface Tension Binary Metal-Surface Active Solute Systems under Conditions Relevant to Welding, Metall. Trans. B, 1988, 19B(6), 483~489
[13]胡汉起.金属凝固.第一版.北京:冶金工业出版社, 1985.55~56
[14]郑启光等.激光与物质交互作.第一版.武汉:华中理工大学出版社, 1996.123~125
[15]扬洗陈等.激光熔池动力学及涂层冶金.见:肖成.全国激光涂层科学与技术研讨会论文集.沈阳:冶金工业出版社,1991. 58~60
[16]范长刚,王爱华,谢长生.铝合金表面激光熔敷的新进展.激光技术, 1996, 20(6):366~369
[17]关振中.激光加工艺手册.第一版.北京:中国计量出版社,1999. 135～138
[18]李言详,沈文.铝表面激光熔敷陶瓷原理和工艺的研究.见:陈斌.第四届全国激光加工学术会议论文集.北京:冶金工业出版社, 1997:5
[19]李力钧.现代激光加工及其装备.第二版.北京:北京理工大学出版社, 1993.86~87
[20]闰毓禾,钟敏霖.高功率激光加工及其应用.第二版.天津:天津科学技术出版社, 1994.132～133
[21]张庆茂,王忠东.工艺参数对送粉激光熔敷几何形貌的影响.焊接学报, 2000, 21(2):43~46
[22]肖荣诗,王智勇等.同步送粉大功率激光表面宽带熔敷技术.应用激光, 2000, 20(3):115~116
[23] J. M. Pelletier. Microstructure and mechanical properties of some metal matrix composites coating by laser cladding. Journal De Physique, 1994, 4(4):93～96
[24]曾晓雁.激光工艺参数对熔敷层宏观质量的影响.金属热处理, 1993, 7:23～2 8
[25]刘喜明,关振中.送粉激光熔敷工艺参数与熔敷层间的关系.金属热处理学报, 1998, 19(1):29~35
[26]刘喜明,关振中.送粉式激光熔敷获得最佳熔敷层的必要条件及其影响因素.中国激光, 1999, 26(5):470~476
[27] OlsenFo. Pulsed Laser Materials Processing-Nd: YAG versus C02 Lasers. in: Annals of the CIRP America: UCD Press, 1995. 141~142
[28]郭伟,徐庆鸿.激光熔敷的研究发展状况.宇航材料工艺, 1998, 2:33～35
[29]李文,关振中.激光熔敷技术及其界面问题发展评述.金属热处理学报, 1997,18(2):45～50
[30]胡木林,谢长生,王爱华.激光熔敷材料相容性的进展.金属热处理, 2001, 21:1~8
[31]尚丽娟,朱荆璞.激光熔授中易产生的问题及对策.金属科学与工艺, 1992, 11(2):65~69
[32]杨永强,田乃良.激光熔敷高温合金及其应用.中国激光, 1995, 22(8):632~636
[33]尚丽娟,阎秀梅等.稀土元素在激光合金化及激光熔敷中的应用,沈阳工业大学学报, 1995, 17(2):37~39
[34]辜磊.铝合金激光-电弧复合焊接工艺研究及其温度场数值模拟: [硕士学位论文],保存地点:华中科技大学图书馆, 2005.
[35] J. Goldar. A New Finite Element Model for Welding Heat Sources. Metallurgical Transactions B, 1984, 15B(6):300~05
[36] M. J. Assael, K. Kakosimos. Reference Data for the Density and Viscosity of Liquid Aluminum and Liquid Iron. Journal of Physics and Chemical Reference Data, 2006, (35): 351~356
[37] V. R. Voller. An enthalpy method for convection/diffusion phase change, International journal for numerical methods in engineering, 1987, (24): 271~284.
[38] V. R. Voller and C. Prakash. A fisec grid numerical modeling methodology for convection-diffusion mushy region phase-change problems, Int. Journal of Heat Mass. Transfer, 1987, (30): 1709~1719,
[39] B. Ghasemi, M. Molki, Melting of unfixed solid in square cavities, Int. Journal of Heat and Fluid Flow, 1999, 20:446~452
[40]虞钢,安永强,胡幼娟.激光加工中传热相变问题的焓解法.中国激光, 2000, (A27): 167~168
[41]周淳楠,郑多宝,张力立.求解固液相变问题的方法.低温与特气, 1994, (2): 20~25
[42]雷永平,史耀武,村川英一.表面流行性元素对Marangoni流和熔池形状影响的数值分析.机械工程学报, 1999, (35): 29~33
[43]杨洗陈.激光熔池中物理输运过程研究.天津工业大学学报, 2002, 21(4):1~7
[44]左铁钏.高强铝合金的激光加工.第二版.北京:国防工业出版社, 2002,10~11
[2]曾大文,谢长生.激光熔敷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
[3] S. Kou, D. K. Sun. Fluid flow and Penetration in stationary Arc Welds, Metall. Trans., 1985, (17A), 203~204
[4] T. Zacharia et al., Modeling of Non-autogenous welding-Model Predicts Three dimensional Convection and Temperature Conditions of the Weld Pool Generated by a Moving Arc, Welding Journal, 1988, 67(1), 18~19
[5] A. F. A. Hoadley et al., Heat Flow Simulation of Laser Remelting with Experimental Validation, Metall. Trans. B, 1991, 22B(2), 101~105
[6] T. Zacharia et al., Modeling of Non-autogenous welding-Model Predicts Three dimensional Convection and Temperature Conditions of the Weld Pool Generated by a Moving Arc, Welding Journal, 1988, 67(3), 53~58
[7] M. C. Tsai, S. Kou. Weld Pool Convection and Expansion due to Density Variations Treatment, Numerical Heat Transfer, 1990, 17(3), 73~77
[8]曹振宁. TIG/MIG焊接熔透熔池流场与热场的研究:[博士学位论文]。保存地点:哈尔滨工业大学图书馆,1993.
[9] A. F. A. Hoadley, M.Rappaz, A Thermal Model of Laser Cladding by Power Injection, Metall. Trans. B, 1992, 23B(10), 631~640
[10]曾大文.激光熔池流场温度场与浓度场的数值分分析:[博士学位论文]。保存地点:华中科技大学图书馆,1998.
[11] T. T. Anthony and H.E. Cline, Surface Rippling Induced by Surface Tension Gradients during Laser Surface Melting and Alloying, Journal of Applied Physics, 1997,48(9):281~285
[12] P. Sahoo et al., Surface Tension Binary Metal-Surface Active Solute Systems under Conditions Relevant to Welding, Metall. Trans. B, 1988, 19B(6), 483~489
[13]胡汉起.金属凝固.第一版.北京:冶金工业出版社, 1985.55~56
[14]郑启光等.激光与物质交互作.第一版.武汉:华中理工大学出版社, 1996.123~125
[15]扬洗陈等.激光熔池动力学及涂层冶金.见:肖成.全国激光涂层科学与技术研讨会论文集.沈阳:冶金工业出版社,1991. 58~60
[16]范长刚,王爱华,谢长生.铝合金表面激光熔敷的新进展.激光技术, 1996, 20(6):366~369
[17]关振中.激光加工艺手册.第一版.北京:中国计量出版社,1999. 135～138
[18]李言详,沈文.铝表面激光熔敷陶瓷原理和工艺的研究.见:陈斌.第四届全国激光加工学术会议论文集.北京:冶金工业出版社, 1997:5
[19]李力钧.现代激光加工及其装备.第二版.北京:北京理工大学出版社, 1993.86~87
[20]闰毓禾,钟敏霖.高功率激光加工及其应用.第二版.天津:天津科学技术出版社, 1994.132～133
[21]张庆茂,王忠东.工艺参数对送粉激光熔敷几何形貌的影响.焊接学报, 2000, 21(2):43~46
[22]肖荣诗,王智勇等.同步送粉大功率激光表面宽带熔敷技术.应用激光, 2000, 20(3):115~116
[23] J. M. Pelletier. Microstructure and mechanical properties of some metal matrix composites coating by laser cladding. Journal De Physique, 1994, 4(4):93～96
[24]曾晓雁.激光工艺参数对熔敷层宏观质量的影响.金属热处理, 1993, 7:23～2 8
[25]刘喜明,关振中.送粉激光熔敷工艺参数与熔敷层间的关系.金属热处理学报, 1998, 19(1):29~35
[26]刘喜明,关振中.送粉式激光熔敷获得最佳熔敷层的必要条件及其影响因素.中国激光, 1999, 26(5):470~476
[27] OlsenFo. Pulsed Laser Materials Processing-Nd: YAG versus C02 Lasers. in: Annals of the CIRP America: UCD Press, 1995. 141~142
[28]郭伟,徐庆鸿.激光熔敷的研究发展状况.宇航材料工艺, 1998, 2:33～35
[29]李文,关振中.激光熔敷技术及其界面问题发展评述.金属热处理学报, 1997,18(2):45～50
[30]胡木林,谢长生,王爱华.激光熔敷材料相容性的进展.金属热处理, 2001, 21:1~8
[31]尚丽娟,朱荆璞.激光熔授中易产生的问题及对策.金属科学与工艺, 1992, 11(2):65~69
[32]杨永强,田乃良.激光熔敷高温合金及其应用.中国激光, 1995, 22(8):632~636
[33]尚丽娟,阎秀梅等.稀土元素在激光合金化及激光熔敷中的应用,沈阳工业大学学报, 1995, 17(2):37~39
[34]辜磊.铝合金激光-电弧复合焊接工艺研究及其温度场数值模拟: [硕士学位论文],保存地点:华中科技大学图书馆, 2005.
[35] J. Goldar. A New Finite Element Model for Welding Heat Sources. Metallurgical Transactions B, 1984, 15B(6):300~05
[36] M. J. Assael, K. Kakosimos. Reference Data for the Density and Viscosity of Liquid Aluminum and Liquid Iron. Journal of Physics and Chemical Reference Data, 2006, (35): 351~356
[37] V. R. Voller. An enthalpy method for convection/diffusion phase change, International journal for numerical methods in engineering, 1987, (24): 271~284.
[38] V. R. Voller and C. Prakash. A fisec grid numerical modeling methodology for convection-diffusion mushy region phase-change problems, Int. Journal of Heat Mass. Transfer, 1987, (30): 1709~1719,
[39] B. Ghasemi, M. Molki, Melting of unfixed solid in square cavities, Int. Journal of Heat and Fluid Flow, 1999, 20:446~452
[40]虞钢,安永强,胡幼娟.激光加工中传热相变问题的焓解法.中国激光, 2000, (A27): 167~168
[41]周淳楠,郑多宝,张力立.求解固液相变问题的方法.低温与特气, 1994, (2): 20~25
[42]雷永平,史耀武,村川英一.表面流行性元素对Marangoni流和熔池形状影响的数值分析.机械工程学报, 1999, (35): 29~33
[43]杨洗陈.激光熔池中物理输运过程研究.天津工业大学学报, 2002, 21(4):1~7
[44]左铁钏.高强铝合金的激光加工.第二版.北京:国防工业出版社, 2002,10~11