1Cr13不锈钢材料电火花表面强化技术的研究
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摘要
电火花表面强化是直接利用电能的高能量密度对工件表面进行强化处理的工艺方法。通过电火花放电作用,将作为电极的导电材料熔渗进金属工件的表面,从而形成合金化的表面强化层,使工件表面的物理、化学和机械性能得到改善,并可在保持基体金属原始性能的前提下修复工件的表面损伤。本文针对水轮机过流部件磨蚀严重这一问题,开展水轮机叶片用1Cr13不锈钢材料电火花表面强化技术的研究,该项研究工作对提高水轮机叶片的表面抗磨蚀性能及使用寿命具有重要的意义。
本文对课题的研究背景及发展现状作了比较全面的综述,对电火花表面强化层的形成规律及其影响因素进行了深入研究,得到了电极-工件重量、强化层厚度及强化层表面形貌随强化时间、电极材料以及电参数的变化规律。结果表明,通过选择和控制强化工艺参数(放电电压、电容、脉冲频率、峰值电流、脉宽及强化时间等)可以在保证强化层厚度的前提下,有效地提高强化效率和强化层质量。
综合考虑实际放电过程中存在的熔融、气化等复杂相变现象,热源半径时变性以及热流密度不等幅性等因素对电火花表面强化过程的影响,采用等效比热法处理电火花表面强化过程中的相变潜热问题,应用APDL参数化编程完成对时变不等幅的单脉冲电火花放电热源的加载,建立了电极融滴在工件表面涂覆过程的有限元仿真模型,实现了对单脉冲电火花强化区域温度场及热应力场的数值模拟。系统地分析了温度场及热应力场随时间的变化规律,为电火花表面强化工艺方法的选择和控制提供了理论依据。
利用扫描电子显微镜和X射线衍射仪对强化层的金相组织、元素分布以及相结构进行分析,并通过显微硬度实验和试件长磨实验对强化层硬度及摩擦磨损性能进行研究。结果表明,强化层的硬度和耐磨性显著高于工件基体,强化层的硬度在白亮层最高,在强化层与基体的结合区硬度降低,在热影响区达到最低。选择高硬度、高合金化的电极材料及合理的电参数可以获得高硬度、高耐磨性能的强化层。选用YG6和WC电极生成的电火花表面强化层其硬度可比工件基体提高2~3倍,耐磨性能亦有显著提升。
Electrical discharge machining (EDM) surface strengthening is a processing method that makes the workpiece surface hardened by using the energy density of electric energy derectly. By the spark discharge effect, the conductive electrode materials melt and infiltrate into the surface of the workpiece, then become the alloying surface strengthening layer, which can make the physical, chemical and mechanical properties of the workpiece surface improved, and repair the workpiece surface damage with maintaining the properties of the workpiece matrix. In this paper, for the abrasion phenomenons of the turbine flowing-passage components are very serious, the study on the EDM surface strengthening of stainless steel 1Cr13 is carried out. As a result, this research work has a great significance for improving the anti-abrasion property and extending the service life of the turbine blades.
In this paper, the background and the development status of the research issue are comprehensively reviewed, the formation laws and the influencing factors of EDM surface strengthening layer are researched deeply, and the variation laws of the electrode-workpiece weight, the strengthening layer thickness, and the surface morphology with enhancing time, electrode materials, and electrical parameters are obtained. The results show that, in the premise of ensuring the strengthening layer thickness, the qualities of the strengthening layer and the efficiency of the strengthening process can be improved by selecting and controling the process parameters (discharge voltage, capacitance, pulse frequency, peak current, pulse width and enhanced time).
The latent heat problem of EDM surface strengthening process was dealt with by method of equivalent specific heat, and the time-varying and unequal amplitude heat flux of single-pulse electric spark discharge was loaded by APDL Programing. The finite element simulation model of the electrode melting drops coating process on the workpiece was established, and the numerical simulation of the temperature field and thermal stress field of the single-pulse electric spark discharge strengthening region was carried out. Thus the variation laws of the temperature field and thermal stress field with the time are detailedly analysised, which provides the theoretical basis for selecting and controling the process parameters.
The microstructure, the elements distribution, and the phase structure of the strengthening layer are analysised by using scanning electron microscopy and X-ray diffraction, the hardness and the wearing resistance of the strengthening layer are studied by micro-hardness test and wear test. The results show that, the hardness and the wearing resistance of the strengthening layer are significantly higher than that of the workpiece matrix. The strengthening layer with high hardness and high wearing resistance can be obtained by selecting high hardness, high alloying electrode materials and reasonable electrical parameters. The hardness of the EDM surface strengthening layers generated by YG6 and WC electrodes is 2 to 3 times more than that of the workpiece matrix, and the wearing resistance of the strengthening layers is also improved significantly.
本文对课题的研究背景及发展现状作了比较全面的综述,对电火花表面强化层的形成规律及其影响因素进行了深入研究,得到了电极-工件重量、强化层厚度及强化层表面形貌随强化时间、电极材料以及电参数的变化规律。结果表明,通过选择和控制强化工艺参数(放电电压、电容、脉冲频率、峰值电流、脉宽及强化时间等)可以在保证强化层厚度的前提下,有效地提高强化效率和强化层质量。
综合考虑实际放电过程中存在的熔融、气化等复杂相变现象,热源半径时变性以及热流密度不等幅性等因素对电火花表面强化过程的影响,采用等效比热法处理电火花表面强化过程中的相变潜热问题,应用APDL参数化编程完成对时变不等幅的单脉冲电火花放电热源的加载,建立了电极融滴在工件表面涂覆过程的有限元仿真模型,实现了对单脉冲电火花强化区域温度场及热应力场的数值模拟。系统地分析了温度场及热应力场随时间的变化规律,为电火花表面强化工艺方法的选择和控制提供了理论依据。
利用扫描电子显微镜和X射线衍射仪对强化层的金相组织、元素分布以及相结构进行分析,并通过显微硬度实验和试件长磨实验对强化层硬度及摩擦磨损性能进行研究。结果表明,强化层的硬度和耐磨性显著高于工件基体,强化层的硬度在白亮层最高,在强化层与基体的结合区硬度降低,在热影响区达到最低。选择高硬度、高合金化的电极材料及合理的电参数可以获得高硬度、高耐磨性能的强化层。选用YG6和WC电极生成的电火花表面强化层其硬度可比工件基体提高2~3倍,耐磨性能亦有显著提升。
Electrical discharge machining (EDM) surface strengthening is a processing method that makes the workpiece surface hardened by using the energy density of electric energy derectly. By the spark discharge effect, the conductive electrode materials melt and infiltrate into the surface of the workpiece, then become the alloying surface strengthening layer, which can make the physical, chemical and mechanical properties of the workpiece surface improved, and repair the workpiece surface damage with maintaining the properties of the workpiece matrix. In this paper, for the abrasion phenomenons of the turbine flowing-passage components are very serious, the study on the EDM surface strengthening of stainless steel 1Cr13 is carried out. As a result, this research work has a great significance for improving the anti-abrasion property and extending the service life of the turbine blades.
In this paper, the background and the development status of the research issue are comprehensively reviewed, the formation laws and the influencing factors of EDM surface strengthening layer are researched deeply, and the variation laws of the electrode-workpiece weight, the strengthening layer thickness, and the surface morphology with enhancing time, electrode materials, and electrical parameters are obtained. The results show that, in the premise of ensuring the strengthening layer thickness, the qualities of the strengthening layer and the efficiency of the strengthening process can be improved by selecting and controling the process parameters (discharge voltage, capacitance, pulse frequency, peak current, pulse width and enhanced time).
The latent heat problem of EDM surface strengthening process was dealt with by method of equivalent specific heat, and the time-varying and unequal amplitude heat flux of single-pulse electric spark discharge was loaded by APDL Programing. The finite element simulation model of the electrode melting drops coating process on the workpiece was established, and the numerical simulation of the temperature field and thermal stress field of the single-pulse electric spark discharge strengthening region was carried out. Thus the variation laws of the temperature field and thermal stress field with the time are detailedly analysised, which provides the theoretical basis for selecting and controling the process parameters.
The microstructure, the elements distribution, and the phase structure of the strengthening layer are analysised by using scanning electron microscopy and X-ray diffraction, the hardness and the wearing resistance of the strengthening layer are studied by micro-hardness test and wear test. The results show that, the hardness and the wearing resistance of the strengthening layer are significantly higher than that of the workpiece matrix. The strengthening layer with high hardness and high wearing resistance can be obtained by selecting high hardness, high alloying electrode materials and reasonable electrical parameters. The hardness of the EDM surface strengthening layers generated by YG6 and WC electrodes is 2 to 3 times more than that of the workpiece matrix, and the wearing resistance of the strengthening layers is also improved significantly.
引文
1徐滨士等.表面工程新技术.国防工业出版社, 2002: 1~8
2曾晓雁等.表面工程学.机械工业出版社, 2001: 15~16
3刘江南.金属表面工程学.兵器工业出版社, 1995: 45~76
4张清.金属磨损和金属耐磨材料手册.冶金工业出版社, 1991:79~83
5陈全明.金属材料及强化技术.同济大学出版社, 1991: 89~95
6陈钟燮.电火花表面强化工艺.机械工业出版社, 1987: 5~8
7罗洪军.电火花堆焊在机器零部件修复上的应用.科学发展月刊. 1998, 30(5): 14 ~16
8 Ajit Singh, Amitabha Ghosh. A Thermo-electric Model of Material Removal during Electric Discharge Machining. International Journal of Machine Tool & Manufacture. 1999, 39(4): 57 ~59
9蔡春鸿,郑光凯,杜家庆,吴宗学.高密度电浆源设计制作及其应用在半导体制程之发展情况.科学发展月刊. 2000, 44(7): 35~38
10介利伟,楼乐明,李明辉.放电通道的波动性与电火花加机理.上海交通大学学报. 2007, 35(7): 989~992
11 B.Lauwers, J.E.Kruth, W.Liu, W.Eeraerts, B.Schacht, P.Bleys. Investigation of Matrial Removal Mechanisms in EDM of Composite Ceramic Materials. Journal of Materials Processing Technology. 2004, 149(1): 347~352
12 C.S.Trueman, J.Huddleston. Material Removal by Spalling during EDM of Ceramics. Jounal of the European Ceramic Society. 2000, 20(10): 1629~1635
13 Takeo Tamura, Yoshinobu Kobayashi. Measurement of Impulsive Forces and Crater Formation in Impulse Discharge. Jounal of Materials Processing Technology. 2004, 149(3): 212~216
14 Daryl D Dibitonto, Philip T Eubank, Mukund R Patel. Theoretical Models of the Electrical Discharge Machining Process. A Simple Cat Hode Erosion Model, 1989: 21~26
15 Mukund R Patel, Maria A Barrufet, Philip T Eubank. Theoretical Models of the Electrical Discharge Machining Process. The Anode Erosion Model, 1989: 125~126
16 Philip T Eubank, Mukund R Patel. Theoretical Models of the Electrical Discharge Machining Process. A Simple Cathode Erosion Model, 1993: 332~336
17 R.Karthikeyan, R.Adalarasan, B.C.Pai. Parametric Optimization to Minimise the Surface Roughness on the Machining of GFRP Composites. Journal of Materials Science & Technology. 2006, 22(1): 66~72
18 Friedhelm Altpeter, Roberto Perez. Relevant Topics in Wire Electrical Discharge Machine Control. Journal of Materials Processing Technology. 2004, 149(1): 147~151
19 Kuo-Ming Tsai, Pei-Jen Wang. Comparisons of Neural Network Models on Material Removal Rate. Journal of Materials Processing Technology. 2001, 117(1): 111~124
20 Frangini S, Masci A, Di Bartolomeo. A Cr7C3-based Cermet Coating Deposited on Stainless Steel by Electrospark Process. Surface and Coatings Technology. 2002, 149(2): 279~286
21 N.Parkansky, I.I.Beilis.L. Rapoport Electrode Erosion and Coating Properties in Pulsed Air Arc Deosition of WC-based Hard Alloys. Surface and Coatings Technology. 1998, 105(1): 130~134
22 Masanori Kunieda, Tsutomu Takaya, Shintaro Nakano. Improvement of Dry EDM Characteristics Using Piezoelectric Actuator. CIRP Annals-Manufacturing Technology. 2004, 55(1): 183~186
23 N Mohri, Y Fukuzawa. Some Considerations to Machining Characteristics of Insulating Ceramics. Journal of Materials Processing Technology. 2002, 52(4): 31~36
24 E Levashov, A Kudryashov, E K Harlamov. Formation of FGM Coating by the New Method of Thermoreactive Electrospark Surface Strengthening. CIRP Annals-Manufacturing Technology. 2002, 51(1): 161~164
25 Li Zhengwei, Gao Wei, Yoshihara M, He Yedong. Improving Oxidation Resistance of Ti3Al and TiAl Intermetallic Compounds with Electro-spark Deposit Coatings. Materials Science and Engineering A. 2003, 347(3): 243~252
26 Liang J, Gao W, Li Z. Hot Corrosion Resistance of Electro Spark-deposited Al and Ni-Cr Coatings Containing Dispersed Y2O3 Particles. Journal of Materials Processing Technology. 2004, 30(8): 1232~1236
27 Podchernyaeva I, Lavrenko, Berezanskaya. Electro-spark Alloying of the Titanium Alloy VT6 with Tungsten-free Hard Alloys. Powder Metallurgy and Metal Ceramics. 2006, 35(11): 588-591
28汪瑞军.钛合金表面WC-Co强化层的电火花表面强化行为研究.焊接. 2005, 33(1):84~103
29汪瑞军,李延军,黄小鸥.电火花表面强化工艺的参数优化.焊接. 2004, 20(8): 21~24
30汪瑞军,张天剑,黄小鸥. Ti合金表面电火花强化工艺参数的优化.机械工人(热加工). 2004, 17( 9 ): 32~34
31陈文华,王德新,魏妹恒.钛合金电火花沉积硬质合金的强化工艺研究.机械工人(冷加工). 2004, 29( 8 ): 21 ~23
32 Akin J E著,张纪刚译.有限元法的应用与实现.科学出版社, 1992: 255~257
33 M.R.Patel, M.A.Barrufet, P.T.Eubank. Theoretical Model of the Electrical Discharge Machining Process. The Anode Erosion Model, 1989: 4104~4111
34 Murali M.S., Yeo.S.H.. Process Simulation and Residual Stress Estimation of Microelectrodischange Machining using Finite Element Method. Japan Journal of Applied Physics. 2005, 44(3): 5254~5263
35 Yeo.S.H., Kurnia.W., Tan.P.C.. Electro-thermal Modeling of Anode and Cathode in Micro-EDM. Journal of Physics D: Applied Physics . 2007, 40(8): 2513~2521
36 Das.S., Koltz.M., Klocke.F.. EDM Simulation: Finite Element-bases Calculation of Deformation, Microstructure and Residual Stress. Journal of Materials Processing Technology. 2006, 142: 434~451
37 Lasagni.A., Soldera.F., Mucklich.f.. FEM Simulation of Local Heating and Melting During Electrical Discharge Plasma Impact. Modeling and Simulation in Materials Science and Engineering. 2003, 142(2): 434~451
38 Das Shuvra, etal. EDM Simulation Finite Element based Calculation of Deformation Icrostmcture and Residual Stresses. Journal of Materials Processing Technology. 2009, 132(5): 421~429
39 Rebelo J C, etal. Residual Stress after EDM-FEM Study and Measurement Results. Materials Science Forum. 2002, 404(5): 159~164
40黄志刚,郭钟宁.单脉冲电火花加工温度场的有限元分析.广东工业火学学报. 2002, 12(8): 38~43
41宋小中.电火花微细加工的工艺研究.电加工. 1995, 6(2): 14~18
42 Heng Xia, Kunieda, Nishiwaki, etal. Measurement of Energy Distribution Into Electrode In EDM Process. Advancement of Intellihgent Production. 2004, 55(11): 601~606
43赵福令,周锦进.电火花加工对模具表面的影响.电加工. 1996, 13(5): 8~10
44李明辉.电火花加工理论基础.国防工业出版社, 1989: 345~350
45 P.T.Eubank, M.R.Patel, M.A.Barrufet etal. Theoretical Model of the Electrical Discharge Machining Process. Advancement of Intellihgent Production. 2006, 73(9): 790
46 Ikai T, Hashigushi K. Heat Input for Crater Formation in EDM. Proceedings of International Symposium for Electro Machining. Advancement of Intellihgent Production. 2008, 3: 163~170
47谭真,郭广文.工程合金热物性.冶金工业出版社, 1994: 130~131, 223~224
48 K-H哈比希著,严立译.材料的磨损与硬度.机械工业出版社, 1990: 644~646
49 Coveney V A, Menger C. Behavior of Model Abrasive Particles between a SlidingElastomer Surface and a Steel Counter Face. Wear. 2007, 240: 72~79
50 Hua Y Q, Chen R F. Study on Wear-resistance of Laser Quenched and Shocked 40Cr Steel. Tribology. 2007, 23(5): 448~450
2曾晓雁等.表面工程学.机械工业出版社, 2001: 15~16
3刘江南.金属表面工程学.兵器工业出版社, 1995: 45~76
4张清.金属磨损和金属耐磨材料手册.冶金工业出版社, 1991:79~83
5陈全明.金属材料及强化技术.同济大学出版社, 1991: 89~95
6陈钟燮.电火花表面强化工艺.机械工业出版社, 1987: 5~8
7罗洪军.电火花堆焊在机器零部件修复上的应用.科学发展月刊. 1998, 30(5): 14 ~16
8 Ajit Singh, Amitabha Ghosh. A Thermo-electric Model of Material Removal during Electric Discharge Machining. International Journal of Machine Tool & Manufacture. 1999, 39(4): 57 ~59
9蔡春鸿,郑光凯,杜家庆,吴宗学.高密度电浆源设计制作及其应用在半导体制程之发展情况.科学发展月刊. 2000, 44(7): 35~38
10介利伟,楼乐明,李明辉.放电通道的波动性与电火花加机理.上海交通大学学报. 2007, 35(7): 989~992
11 B.Lauwers, J.E.Kruth, W.Liu, W.Eeraerts, B.Schacht, P.Bleys. Investigation of Matrial Removal Mechanisms in EDM of Composite Ceramic Materials. Journal of Materials Processing Technology. 2004, 149(1): 347~352
12 C.S.Trueman, J.Huddleston. Material Removal by Spalling during EDM of Ceramics. Jounal of the European Ceramic Society. 2000, 20(10): 1629~1635
13 Takeo Tamura, Yoshinobu Kobayashi. Measurement of Impulsive Forces and Crater Formation in Impulse Discharge. Jounal of Materials Processing Technology. 2004, 149(3): 212~216
14 Daryl D Dibitonto, Philip T Eubank, Mukund R Patel. Theoretical Models of the Electrical Discharge Machining Process. A Simple Cat Hode Erosion Model, 1989: 21~26
15 Mukund R Patel, Maria A Barrufet, Philip T Eubank. Theoretical Models of the Electrical Discharge Machining Process. The Anode Erosion Model, 1989: 125~126
16 Philip T Eubank, Mukund R Patel. Theoretical Models of the Electrical Discharge Machining Process. A Simple Cathode Erosion Model, 1993: 332~336
17 R.Karthikeyan, R.Adalarasan, B.C.Pai. Parametric Optimization to Minimise the Surface Roughness on the Machining of GFRP Composites. Journal of Materials Science & Technology. 2006, 22(1): 66~72
18 Friedhelm Altpeter, Roberto Perez. Relevant Topics in Wire Electrical Discharge Machine Control. Journal of Materials Processing Technology. 2004, 149(1): 147~151
19 Kuo-Ming Tsai, Pei-Jen Wang. Comparisons of Neural Network Models on Material Removal Rate. Journal of Materials Processing Technology. 2001, 117(1): 111~124
20 Frangini S, Masci A, Di Bartolomeo. A Cr7C3-based Cermet Coating Deposited on Stainless Steel by Electrospark Process. Surface and Coatings Technology. 2002, 149(2): 279~286
21 N.Parkansky, I.I.Beilis.L. Rapoport Electrode Erosion and Coating Properties in Pulsed Air Arc Deosition of WC-based Hard Alloys. Surface and Coatings Technology. 1998, 105(1): 130~134
22 Masanori Kunieda, Tsutomu Takaya, Shintaro Nakano. Improvement of Dry EDM Characteristics Using Piezoelectric Actuator. CIRP Annals-Manufacturing Technology. 2004, 55(1): 183~186
23 N Mohri, Y Fukuzawa. Some Considerations to Machining Characteristics of Insulating Ceramics. Journal of Materials Processing Technology. 2002, 52(4): 31~36
24 E Levashov, A Kudryashov, E K Harlamov. Formation of FGM Coating by the New Method of Thermoreactive Electrospark Surface Strengthening. CIRP Annals-Manufacturing Technology. 2002, 51(1): 161~164
25 Li Zhengwei, Gao Wei, Yoshihara M, He Yedong. Improving Oxidation Resistance of Ti3Al and TiAl Intermetallic Compounds with Electro-spark Deposit Coatings. Materials Science and Engineering A. 2003, 347(3): 243~252
26 Liang J, Gao W, Li Z. Hot Corrosion Resistance of Electro Spark-deposited Al and Ni-Cr Coatings Containing Dispersed Y2O3 Particles. Journal of Materials Processing Technology. 2004, 30(8): 1232~1236
27 Podchernyaeva I, Lavrenko, Berezanskaya. Electro-spark Alloying of the Titanium Alloy VT6 with Tungsten-free Hard Alloys. Powder Metallurgy and Metal Ceramics. 2006, 35(11): 588-591
28汪瑞军.钛合金表面WC-Co强化层的电火花表面强化行为研究.焊接. 2005, 33(1):84~103
29汪瑞军,李延军,黄小鸥.电火花表面强化工艺的参数优化.焊接. 2004, 20(8): 21~24
30汪瑞军,张天剑,黄小鸥. Ti合金表面电火花强化工艺参数的优化.机械工人(热加工). 2004, 17( 9 ): 32~34
31陈文华,王德新,魏妹恒.钛合金电火花沉积硬质合金的强化工艺研究.机械工人(冷加工). 2004, 29( 8 ): 21 ~23
32 Akin J E著,张纪刚译.有限元法的应用与实现.科学出版社, 1992: 255~257
33 M.R.Patel, M.A.Barrufet, P.T.Eubank. Theoretical Model of the Electrical Discharge Machining Process. The Anode Erosion Model, 1989: 4104~4111
34 Murali M.S., Yeo.S.H.. Process Simulation and Residual Stress Estimation of Microelectrodischange Machining using Finite Element Method. Japan Journal of Applied Physics. 2005, 44(3): 5254~5263
35 Yeo.S.H., Kurnia.W., Tan.P.C.. Electro-thermal Modeling of Anode and Cathode in Micro-EDM. Journal of Physics D: Applied Physics . 2007, 40(8): 2513~2521
36 Das.S., Koltz.M., Klocke.F.. EDM Simulation: Finite Element-bases Calculation of Deformation, Microstructure and Residual Stress. Journal of Materials Processing Technology. 2006, 142: 434~451
37 Lasagni.A., Soldera.F., Mucklich.f.. FEM Simulation of Local Heating and Melting During Electrical Discharge Plasma Impact. Modeling and Simulation in Materials Science and Engineering. 2003, 142(2): 434~451
38 Das Shuvra, etal. EDM Simulation Finite Element based Calculation of Deformation Icrostmcture and Residual Stresses. Journal of Materials Processing Technology. 2009, 132(5): 421~429
39 Rebelo J C, etal. Residual Stress after EDM-FEM Study and Measurement Results. Materials Science Forum. 2002, 404(5): 159~164
40黄志刚,郭钟宁.单脉冲电火花加工温度场的有限元分析.广东工业火学学报. 2002, 12(8): 38~43
41宋小中.电火花微细加工的工艺研究.电加工. 1995, 6(2): 14~18
42 Heng Xia, Kunieda, Nishiwaki, etal. Measurement of Energy Distribution Into Electrode In EDM Process. Advancement of Intellihgent Production. 2004, 55(11): 601~606
43赵福令,周锦进.电火花加工对模具表面的影响.电加工. 1996, 13(5): 8~10
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