摘要
安全、节能和环保是汽车技术发展的永恒主题,汽车轻量化是满足上述要求的有效手段和方法。双相钢等先进高强钢材料以其良好的成形性及耐撞性等优点正在轻量化车身制造中得到越来越广泛的应用。例如:在车身前纵梁、B柱等关键部位低碳钢内外板与双相钢加强件的差强差厚三层钢板匹配工况显著增加,应用比例达33%。而采用传统电阻点焊工艺连接差强差厚多层钢板时常常会带来焊接飞溅严重、工艺窗口狭窄和电极磨损剧烈等问题。为此,汽车制造商试图采用韧性结构胶接技术部分替代电阻点焊工艺,但受环境温度、湿度和胶粘剂老化等因素影响,胶接接头强度波动大,难以满足车身承载能力要求。因此,电阻点焊与胶接的复合连接工艺(简称胶焊技术),因其综合了上述两种连接工艺的技术优点,是目前多层钢板连接的首选工艺方法。然而,在差强差厚多层钢板胶焊过程中,受胶层和钢板材料属性的影响,熔核形成规律及质量控制复杂。例如:胶层的高粘稠性使钢板间接触不充分,引起通电生热异常,甚至难以焊接。差强钢板材料电阻率、导热率等物理属性的差异,使胶焊熔核区温度场分布不均匀,带来熔核偏移问题,熔核尺寸难以保证。因此,迫切需要开展差强差厚多层钢板胶焊熔核形成机理及质量控制方法的研究。
为解决上述问题,本文以差厚差强三层钢板胶焊过程为研究对象,从胶层入手,分析了胶焊预压过程中胶层耦合作用下的钢板间接触电阻变化规律、焊接通电过程中钢板-胶层间的传热行为及其对胶焊动态电阻的影响,建立了三层钢板胶焊熔核形成过程的有限元模型,揭示了差强差厚三层钢板胶焊熔核形成机理及熔核偏移的内在原因。基于上述理论研究结果,提出了用于改善熔核偏移的不对称电场输入方法,形成了三层钢板胶焊工艺规范,推动了多层钢板胶焊技术在汽车车身制造中的应用。全文开展的主要研究工作如下:
1)胶焊预压过程中胶层耦合作用下的钢板间接触电阻变化规律
针对韧性胶层的高粘稠性导致的钢板间接触不充分问题,建立了考虑胶层膜电阻的钢板间接触电阻模型,获得了预压阶段中钢板间接触电阻变化规律,确定了保证钢板间充分接触的胶焊临界预压力。研究结果显示,预压后残留于钢板表面的胶粘剂形成的胶层膜电阻会使得钢板间接触电阻增大。高粘稠度的胶层种类引起的钢板间接触电阻上升更明显;而胶层厚度(0~1.4 mm)对于钢板间接触电阻影响不显著。对于厚度为0.8 mm的DC04, 1.4 mm的DP600和1.8 mm的DP780钢板,使其充分接触的临界预压电极力分别约为1.0 kN, 3.0 kN和4.5 kN。
2)胶焊通电过程中钢板-胶层间的传热行为及动态电阻变化规律
针对胶焊过程生热异常、飞溅严重问题,通过分析胶焊通电过程中钢板与胶层间的传热行为建立了胶焊动态电阻方程。研究发现,相同条件下胶焊过程中的电阻热由于钢板间接触电阻的增大而增多,而散热量却由于钢板表面通过空气向外散热的途径受到胶层阻碍而减少,这使得胶焊动态电阻比传统电阻点焊有所上升:粘稠度较大的胶层引起的动态电阻上升量更大;而胶层厚度并无显著影响;且同时涂有两层胶粘剂的三层钢板胶焊接头具有最大的动态电阻。
3)差强差厚三层钢板胶焊熔核形成规律
针对差强差厚三层钢板胶焊熔核偏移问题,建立了考虑胶层作用下界面接触状态的三层钢板胶焊过程有限元模型,分析了三层钢板胶焊熔核形成过程,揭示了差厚差强三层钢板熔核形成机理及熔核偏移的内在原因。研究发现,差厚差强三层钢板胶焊熔核在两个钢板间接触面上的形成时刻不同是造成熔核偏移的关键原因。对于厚度为0.8 mm DC04+1.4 mm DP600 + 1.8 mm DP780的三层钢板胶焊,熔核在两个钢板间接触面上的形成时间差约80 ms,胶层的存在使得相同电流下三层钢板胶焊熔核的形成时刻比无胶层存在时提前约40 ms。粘稠度较大的胶层能获得较大的熔核尺寸;而胶层厚度对于熔核尺寸的影响并不显著。
4)差强差厚三层钢板胶焊工艺优化
基于上述研究结果,分析了胶层涂覆位置、板材厚度匹配、板材匹配顺序等工艺因素对于差强差厚三层钢板胶焊熔核偏移影响规律。研究结果发现,只在薄板侧涂覆胶层或薄板侧钢板选用高强钢能使该侧熔核增大,有利于减小熔核偏移。在差强差厚三层钢板接头中,上下层钢板的厚度比不应超过1:3。为更好地提升胶焊质量,提出了采用4+6 mm电极的不对称电场输入工艺优化方法,此方法不仅可获得较大的熔核尺寸,还可拓宽三层钢板胶焊工艺窗口50%。
综上所述,本文对于差强差厚三层钢板胶焊的熔核形成过程及其质量问题的成因进行了系统地研究,并提出了三层钢板胶焊工艺优化方法,为推动三层钢板胶焊工艺在汽车车身制造中的应用奠定了基础。
Automotive lightweight is an effective way to realize the vehicle development for safety, energy conservation and environmental protection. Advanced high strength steels, such as dual phase steel, are steadily applied more and more widely in light-weighting auto-body manufacturing in the advantages of good forming and crash performance. For example, in side rail and B pillar assemblies, there are many joints made with three steel sheets including low carbon steels and dual phase steels. The application of multiple steels joint reaches about 33% of a joint on a common vehicle. However, when resistance spot welding, as the main joining method in production, applied to multiple sheet stackups, issues such as weld expulsion, narrow weld lobe and interfacial failure have developed. To deal with these issues, some vehicle manufacturers try to partly replace resistance spot welding with adhesive bonding technology. But the bond quality is significantly affected by the production environmental, like temperature, humidity, etc., and consequently the adhesive bonding is hard to meet the requirements of the vehicle body. As a result, the combination of adhesive bonding and resistance spot welding, called as weld-bonding, is recognized as the preferred method to join three steel sheets. However, weld-bonding of three steel sheets is affected by both the adhesive layer and steel properties. The viscous adhesive would make the steel sheets hard to contact enough. Dissimilar steel grades and thicknesses would lead to the unbalance distribution of the electric and temperature field in weld-bonding. The combination of these effects resulted in the weld nugget shift, and consequently it is hard to control the weld quality in weld-bonding of three sheet stackup. Thereforce, it is imperative to study the mechanism of weld-bonding of three sheet stackup to improve the weld quality.
In this dissertation, the weld-bonding of three sheet stackup is focused on by starting from the adhesive layer. Theoretical analysis and experimental methods have been employed to study the contact resistance between the steel sheets with the adhesive during the squeezing stage, and the heat transfer and dynamic resistance during the welding stage. Based on these two aspects and considering the different properties of dissimilar steel sheets, a finite element model was developed to model the welding process and reveal the mechanism of weld-bonding of three steel sheets with various strengths and thicknesses. Furthermore, a new method using asymmetric electric field input was brought up to deal with the weld nugget shifting phenomenon and improve the weld quality in weld-bonding of with three steel sheets. Process specifications for weld-bonding of three steel sheets were established to widen the application in the auto-body. The main content in this dissertation contains four parts:
1) Contact resistance between the steel sheets with the adhesive during the squeeze cycle
Since the viscous adhesive is used, the steel sheets could have a poor contact under a given electrode force, and consequently result in the weld expulsion. To deal with this issue, a theoretical analysis model containing the influence of the adhesive has been brought up to study the contact regulations between the steel sheets with adhesive layer. The results showed that the remaining adhesive on the surface of the steel sheet increases the film resistance, and consequently the total contact resistance between steel sheets rises. The larger the adhesive viscosity is, the more the contact resistance would increase. However, the thickness of the adhesive layer takes little influence. It has also been found that a suitable electrode force is required to obtain the proper contact between the steel sheets in weld-bonding. The minimum electrode force to ensure the contact state in weld-bonding of 0.8 mm thick DC04, 1.4 mm thick DP600 and 1.8 mm thick DP780 is about 1.0 kN, 3.0 kN and 4.5 kN, respectively.
2) Heat transfer and dynamic resistance between the steel sheets with the adhesive during the welding cycle
During the welding cycle of weld-bonding, the adhesive change in heat is complicatedly coupled with the joule heat generation, which makes the process of weld-bonding obviously different from the traditional spot welding. To solve this problem, an equation for the balance between the heat generation and cooling in weld-bonding was established. On this basis, it was found that the adhesive not only increased the heat generation during welding due to the great contact resistance, but also minimized the heat loss on the steel surface. As a result, the dynamic resistance during welding for weld-boding increased significantly comparing to that for spot welding. Furthermore, test results showed that the weld-bonding with a high viscous adhesive had greater dynamic resistance than that with a low viscous adhesive. The adhesive thickness affects the dynamic resistance little. Extensive tests were peformed to asses the effect of the adhesive placement on the weld-bonding of three sheet stackup and test results showed that two layers of the adhesive palced between the three sheet stackup produced the maximum dynamic resistance.
3) Weld nugget formation in weld-bonding with three dissimilar steel sheets
The weld nugget shifting phenomenon is common in weld-bonding of three steel sheets and it would degrade the weld quality. A finite element model considering the effect of the adhesive on the contact state between the steel sheets has been established to study on this issue. Model results showed the weld nugget formation process of weld-bonding with various types and thicknesses of steel sheets and different adhesive layers by structure, electric and temperature field to reveal the mechanism of weld-bonding with three steel sheets. It was found that the different time of nugget initiation on the two interfaces between steel sheets is the key reason for the weld nugget shifting. However, the nugget initial time is closely related to the properties of steel sheets and adhesive. In the weld-bonding with 0.8 mm thick DC04, 1.4 mm thick DP600 and 1.8 mm thick DP780, the initial time of weld nugget on the interface between 1.4 mm thick DP600 and 1.8 mm thick DP780 was about 80 ms earlier than that between 0.8 mm thick DC04 and 1.4 mm thick DP600. Additionally, the weld nugget in weld-bonding initiated earlier 40 ms than that of spot welding with the same welding parameters. Weld-bonding with a high viscous adhesive gets a big weld nugget; however, the adhesive thickness affects little.
4) Weld nugget shifting and process optimization of weld-bonding with three dissimilar steel sheets
Based on the research result about the mechanism of weld-bonding of three dissimilar steel sheets, process specification for detail production condition was established including different placement of adhesive layer, sheet combinations with different thicknesses and orders. It was found that the weld-bonding with one adhesive layer on the thin steel side could get a better weld nugget only on that interface, so it could improve the weld nugget shifting obviously. In a weld-bonding of one low carbon steel and two dual phase steels, the maximum thickness ratio between the top and bottom steel sheets is about 1:3. To further improve the weld quality, a symmetric electric field input method was developed by using different electrode caps to adjust the weld nugget shifting. The results showed that a couple of electrode caps with 4 mm tip diameter as the top one on the thin sheet side and 6 mm tip diameter as the bottom one on the thick sheet side, simply called 4+6 electrodes, had the best efficiency to improve the weld quality.
In summary, modeling and experimental methods have been used in this dissertation to study the mechanism of weld-bonding of three steel sheets. Process specifications and optimization are developed to improve the implementation of weld-bonding of three steel sheets in manufacturing.
引文
[1] Nishimoto Akihiro, Hosoya Yoshihiro, Nakaoka Kazuhide. New type of dual-phase steel sheet for automobile outer body panels. Transactions of the Iron and Steel Institute of Japan, 1981, 21 (11): 778-782.
[2] ULSAB-AVC Consortium, Technical Transfer Dispatch #6 (Body Structure Materials), May 26, 2001.
[3] Murali D. Tumuluru. Resistance Spot Welding of Coated High-Strength Dual-Phase Steels. Welding Journal, 2006 (8): 31-37.
[4] M. Kuo and J. Chiang, Weldability study of resistance spot welds and minimum weld button size methodology development for DP steel. SAE Technical paper series, 2004-01-0169
[5] X. Sun. Effects of fusion zone size on strength and failure modes of advanced high-strength steel spot welds, AWS Detroit Section’s Sheet Metal Welding Conference XII, Livonia, Mich., May 9-12, 2006: 7-2.
[6] M. Marya and X. Q. Gayden. Development of requirements for resistance spot welding dual-phase (DP600) steels part 1: the causes of interfacial fracture. Welding Journal, 2005 (11): 172s-181s.
[7] M. Marya and X. Q. Gayden. Development of requirements for resistance spot welding dual-phase (DP600) steels part 2: statistical analyses and process maps. Welding Journal, 2005 (12):197s-204s
[8] W. Peterson. Method to minimize the occurrence of interfacial fractures in HSS spot welds, AWS Detroit Section’s Sheet Metal Welding Conference XII, Livonia, Mich., May 9-12, 2006: 1-3.
[9] J. H. Song and J. K. Lim. Bonding strength in structural adhesive bonded joint. Metals and Materials International, 2001, 7 (5): 467-470.
[10]张玉龙.胶粘技术手册.中国轻工业出版社. 2001.
[11] A.J. Kinloch, Adhesion and Adhesives. Chapman and Hall Ltd, London, 1987
[12] A.J. Kinloch, Adhesive in engineering. Proceedings Institution of Mechanical Engineers. Part G-Journal of Aerospace Engineering, 1997, 211: 307-335.
[13] A.J. Kinloch. Toughening epoxy adhesives to meet today’s challenges. MRS Bulletin, 2003, 28 (6): 445-448.
[14] J. Qu. Application of high performing adhesive bonding in automotive industry. Report of Sika Technology AG.
[15] J. Giovanoli. Dow betamate adhesives overview. Report of Dow adhesive system, 2010, 3.
[16] Messler and W. Robert. Weld-bonding: The best or worst of two processes? Industrial Robot, 2002, 29 (2):138-148.
[17] V.M. Goncalves and P.A.F. Martins. Static and fatigue performance of weld-bonded stainless steel joints. Materials and Manufacturing Processes, 2006, 21: 774-778.
[18] X. Wu and H.Q. Hao. The effect of adhesive curing condition on bonding strength in autobody assembly. Journal of Manufacturing Science and Engineering, Transactions of the ASME, 2005, 127(2): 411-419.
[19] Prashant Kumara, Shishir Tiwaria and R.K. Singhb. Characterization of toughened bonded interface against fracture and impact loads. International Journal of Adhesion and Adhesives, 2005, 25(6): 527-533.
[20] B.H. Chang, Y.W. Shi and L.Q. Lu. Studies on the stress distribution and fatigue behavior of weld-bonded lap shear joints. Journal of Materials Processing Technology, 2001, 108(3): 307~313.
[21] Y.S. Zhang, H.T. Sun, G.L. Chen and X.M. Lai. Comparison of mechanical properties and microstructure of weld nugget between weld-bonded and spot-welded dual-phase steel. Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture, 2009, 223 (10): 1341-1350.
[22] S.A. Gedeon and E T. Wagar. Resistance spot welding of galvanized steel: part I. material variations and process modifications. Metallurgical Transactions B (Process Metallurgy), 1986, 17 (4): 879-886.
[23] S.A. Gedeon and E T. Wagar. Resistance spot welding of galvanized steel: part II. mechanisms of spot weld nugget formation. Metallurgical Transactions B (Process Metallurgy), 1986, 17 (4): 887-901.
[24]赵熹华,冯吉才.压焊方法及设备.机械工业出版社, 2005.
[25] P.H. Thornton, A.R. Krause and R.G. Davis. Contact resistance in spot welding. Welding Journal, 1996, 75 (12): 402s-421s.
[26] M. Vogler and S. Sheppard. Electrical contact resistance under high loads and elevated temperatures, Welding Journal, 1993, 72: 231-298.
[27] R. Holm. Electric contacts-theory and application. 4th edition, Springer-Verlag, 1967, Berlin.
[28] J.A. Greenwood. Constriction resistance and the real area of contact. British Journal of Applied Physics, 1966, 17: 1621-1632.
[29] W.F. Savage, E.F. Nippes and F.A. Wassell. Dynamic contact resistance of series spot welds, Welding Journal, 1978, 57: 43s-50s.
[30] P.S. James, H.W. Chandler, J.T. Evans, J. Wen, D.J. Browne and C.J. Newton. The effect of Mechanical loading on the contact resistance of coated aluminum, Materials Science and Engineering A, 1997, A230: 194-201.
[31] E. Crinon and J.T. Evans. The effect of surface roughness, oxide film thickness and interfacial sliding on the electrical contact resistance of aluminum, Materials Science and Engineering A, 1998, A242: 121-128.
[32] Ta-chien Sun. Fundamental study of contact resistance behavior in RSW aluminum. Ph. D Dissertation, the Ohio State University, 2003.
[33] Q.F. Song, W.Q. Zhang and N. Bay. An experimental study determines the electrical contact resistance in resistance welding, Welding Journal, 2005, 84 (5): 73s-76s.
[34] Y. Cho and S. Rhee. Primary circuit dynamic resistance monitoring and its application to quality estimation during resistance spot welding. Welding Journal, 2002, 81 (6): 104s-111s.
[35] Wei Li, S. Jack Hu and Jun Ni. On-line quality estimation in resistance spot welding. Journal of Manufacturing Science and Engineering, 2000, 122: 511-512.
[36] C. Ma, S.D. Bhole, D. L. Chen, A. Lee, E. Biro and G. Boudreau. Expulsion monitoring in spot welded advanced high strength automotive steels. Science and Technology of Welding and Joining, 2006, 11 (4): 480-487.
[37] Mahmoud El-Banna1, Dimitar Filev and Ratna Babu Chinnam. Intelligent constant current control for resistance spot welding. 2006 IEEE International Conference on Fuzzy Systems, 2006: 1570-1577.
[38] D.F. Farson, J.Z. Chen, K. Ely et al. Monitoring resistance spot nugget size by electrode displacement. Journal of Manufacturing Science and Engineering, Transactions of the ASME, 2004, 126(2): 391-394
[39] Podr?aj Primo?, Polajnar Ivan, Diaci Janez and Kari? Zoran. Estimating the strength of resistance spot welds based on sonic emission. Science and Technology of Welding and Joining, 2005, 10 (4), 399-405.
[40] N. Harlin, T.B. Jones and J.D. Parker. Weld growth mechanism of resistance spot welds in zinc coated steel. Journal of Materials Processing Technology, 2003, 143-144(1): 448-453.
[41] M. Pouranvari and S.P.H. Marashi. Critical sheet thickness for weld nugget growth during resistance spot welding of three-steel sheets. Science and Technology of Welding and Joining, 2011, 16 (2): 162-165.
[42] C. Srikunwong, T. Dupuy and Y. Bienvenu. Numerical simulation of resistance spot welding process using FEA technique. Proceedings of 13th International Conference on Computer Technology in Welding, Orlando, Florida, June 2003, NIST and AWS: 53-64.
[43] E. Feulvarch, V. Robin and J.M. Bergheau. Resistance spot welding simulation: A general finite element formulation of electrothermal contact conditions. Journal of Materials Processing Technology, 2004, 153-154 (1-3): 436-441.
[44]王春生,陈勇,韩凤武,陆培德,王洪亮.三层不锈钢板电阻点焊温度场数值模拟.机械工程学报, 2004, 40 (1): 191-194.
[45] N. Harlin, T.B. Jones and J.D. Parker. Weld growth mechanisms during resistance spot welding of two and three thickness lap joints. Science and Technology of Welding and Joining, 2002, 7 (1):35-41.
[46] S.M. Darwish, A.M. Al-Samhan. Peel and shear strength of spot-welded and weld-bonded dissimilar thickness joints. Journal of Materials Processing Technology, 2004, 147 (1): 51-59.
[47] Ma Ninshu and Murakawa Hidekazu. Numerical and experimental study on nugget formation in resistance spot welding for three pieces of high strength steel sheets. Journal of Materials Processing Technology, 2010, 210 (14): 2045-2052.
[48] C.V. Nielsen, K.S. Friis, W. Zhang and N. Bay. Three-sheet spot welding of advanced high-strength steels. Welding Journal, 2011, 90 (2): 32s-40s.
[49] T.B. Jones. Weld-bonding - the mechanism and properties of weldbonded joints. Sheet Metal Industries, 1995, 72 (9): 30-31.
[50] P.C. Wang, S.K. Chisholm, G. Banas and F.V. Lawrence Jr. Role of failure mode, resistance spot weld and adhesive on the fatigue behavior of weld-bonded aluminum. Welding Journal, 1995, 74 (2): 41s-47s.
[51] S.M.H. Darwish. Weld-bonding strengthens and balances the stresses in spot-welded dissimilar thickness joints. Journal of Materials Processing Technology, 2003, 134 (3): 352-362.
[52] S.M.H. Darwish and A. Ghanya. Critical assessment of weld-bonded technologies. Journal of Materials Processing Technology, 2000, 105 (3): 221-229.
[53] V.M. Goncalves and Paulo A.F. Martins. Joining stainless steel parts by means of weldbonding. International Journal of Mechanics and Materials in Design, 2006, 3 (1): 91-101.
[54] X. Long and S.K. Khanna. Fatigue performance of spot welded and weld bonded advanced high strength steel sheets. Science and Technology of Welding and Joining, 2008, 13 (3): 241-247.
[55] S. Sam and M. Shome. Static and fatigue performance of weld bonded dual phase steel sheets. Science and Technology of Welding and Joining, 2010, 15 (3): 242-247.
[56] B.H. Chang, Y.W. Shi and S.J. Dong. A study on the role of adhesives in weld-bonded joints. Welding Journal, 1999, 78 (8): 275s-279s.
[57] B.H. Chang, Y.W. Shi and S.J. Dong. Studies on a computational model and the stress field characteristics of weld-bonded joints for a car body steel sheet. Journal of Materials Processing Technology, 2000, 100 (1): 171-178.
[58]常保华,史耀武,胶焊搭接接头的应力分布和疲劳行为研究.机械工程学报, 2000, 36 (2): 106-110.
[59] Arne Melander, Mats Larsson, Hanna Stensio, Anders Gustavsson and Jan. Linder. Fatigue performance of weldbonded high strength sheet steels tested in arctic, room temperature and tropical environments. International Journal of Adhesion and Adhesives, 2000, 20 (5): 415-425.
[60] B. Johansson and A. Olsson. Current design practice and research on stainless steel structures in Sweden. Journal of Constructional Steel Research, 2000, 54 (1): 3-29.
[61] S.M. Darwish and A. Al-Samhan. Thermal stresses developed in weld-bonded joints. Journal of Materials Processing Technology, 2004, 153-154 (1-3): 971-977.
[62] S.M. Darwish. Characteristics of weld-bonded commercial aluminum sheets (B.S.1050). International Journal of Adhesion and Adhesives, 2003, 23 (3): 169-176.
[63] Xia Yong, Zhou Qing, P.C. Wang, N.L. Johnson, X.Q. Gayden and J.D. Fickes. Development of high-efficiency modeling technique for weld-bonded steel joints in vehicle structures-Part I: Static experiments and simulations. International Journal of Adhesion and Adhesives, 2009, 29 (4): 414-426.
[64] Xia Yong, Zhou Qing, P.C. Wang, N.L. Johnson, X.Q. Gayden and J.D. Fickes. Development of high-efficiency modeling technique for weld-bonded steel joints in vehicle structures-Part II: Dynamic experiments and simulations. International Journal of Adhesion and Adhesives, 2009, 29 (4): 427-433.
[65] S. Schreiber. Investigations into three-member welding. Welding and Cutting, 2001, 53 (11): E252-E259.
[66] Sin Su Rok, Yang Sung Mo, Yu Hyo Sun, Kim Chai Won and Kang Hee Yong. Fatigue analysis of multi-lap spot welding of high strength steel by quasi static tensile-shear test. Key Engineering Materials, 2007, 345-346: 251-254.
[67] Kang Hong-Tae, Accorsi Ilaria, Patel Bipin and Pakalnins Eric. Fatigue performance of resistance spot welds in three sheet stack-ups. Procedia Engineering, 2001, 2 (1): 129-138.
[68]韩凤武,王洪亮.多层及非等厚不锈钢板点焊工艺研究.机车车辆工艺, 2004, 4: 19-21.
[69] Hasanbasoglu Ahmet and Ka?ar Ramazan. Resistance spot weldability of dissimilar materials (AISI 316L-DIN EN 10130-99 steels). Materials and Design, 2007, 28 (6): 1794-1800.
[70] P. Marashi, M. Pouranvari, S. Amirabdollahian, A. Abedi and M. Goodarzi. Microstructure and failure behavior of dissimilar resistance spot welds between low carbon galvanized and austenitic stainless steels. Materials Science and Engineering A, 2008, 480 (1-2): 175-180.
[71] S. Daneshpour, S. Riekehr, M. Ko?ak and C.H.J. Gerritsen. Mechanical and fatigue behaviour of laser and resistance spot welds in advanced high strength steels. Science and Technology of Welding and Joining, 2009, 14 (1): 20-25.
[72]中国机械工程学会焊接学会.电阻焊(III)专业委员会,电阻焊理论与实践.机械工业出版社, 1994.
[73] Y.J. Park and H. Cho. Quality evaluation by classification of electrode force patterns in the resistance spot welding process using neural networks. Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture, 2004, 218 (11): 1513-1524.
[74] Roger B. Hirsch and Ronald Leibovitz. The effect of tip force on weld quality and electrode life. Technical Paper - Society of Manufacturing Engineers, 1999, 210: 1-8.
[75] C.T. Ji and Y. Zhou. Dynamic electrode force and displacement in resistance spot welding of aluminum. Journal of Manufacturing Science and Engineering, Transactions of the ASME, 2004, 126 (3): 605-610.
[76] S.J. Na and S.W. Park. Theoretical study on electrical and thermal response in resistance spot welding. Welding Journal, 1996, 75 (8): 233s-241s.
[77] B.H. Chang and Y. Zhou. Numerical study on the effect of electrode force in small-scale resistance spot welding. Journal of Materials Processing Technology, 2003, 139 (1-3): 635-641.
[78] B.H. Chang, D. Du, B. Sui, Y. Zhou, Z. Wang and F. Heidarzadeh. Effect of forging force on fatigue behavior of spot welded joints of aluminum alloy 5182. Journal of Manufacturing Science and Engineering, Transactions of the ASME, 2007, 129 (1): 95-100.
[79]常保华,都东,岁波.锻压力对铝合金点焊接头疲劳行为的影响.焊接学报, 2005, 26 (8): 5-8.
[80] H. Tang, W. Hou, S.J. Hu and H. Zhang. Force characteristics of resistance spot welding of steels. Welding Journal, 2000, 79 (7): 175s-183s.
[81] H. Tang, W. Hou and S.J. Hu. Forging force in resistance spot welding. Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture, 2002, 216 (7): 957-968.
[82] Furukawa Kazutoshi, Katoh Mitsuaki, Nishio Kazumasa and Yamaguchi Tomiko. Relation between welding conditions and temporal change of electrode force - study on the development of electrode force changeable lap resistance spot welding machine and characteristics of welds (report 1). Yosetsu Gakkai Ronbunshu/Quarterly Journal of the Japan Welding Society, 2006, 24 (1): 3-9.
[83] Furukawa Kazutoshi, Katoh Mitsuaki, Nishio Kazumasa and Yamaguchi Tomiko. Influence of electrode pressure and welding conditions on the maximum tensile shear load- study on the development of electrode force changeable lap resistance spot welding machine and characteristics of welds (report 2). Yosetsu Gakkai Ronbunshu/Quarterly Journal of the Japan Welding Society, 2006, 24 (1): 10-16.
[84] X.Y. Zhang, G.L.Chen and Y.S. Zhang. Improvement of resistance spot weldability for dual-phase (DP600) steels using servo gun, Journal of Materials Processing Technology, 2009, 209 (5): 2671–2675.
[85]孙海涛,张延松,陈关龙, P.C. Wang.电极力对双相钢点焊质量影响分析. 2009先进焊接与连接学术会议暨第一届焊接高层论坛, 2009 (1): 82-85.
[86] ANSI/AWS/SAE/D8.9-97, Recommended Practices for Test Methods for Evaluating the Resistance Spot Welding Behavior of Automotive Sheet Steel Materials, American Welding Society, 1997.
[87] D.W. Dickinson, J.E. Franklin and A. Stanya. Characterization of spot welding behavior by dynamic electrical parameter monitoring, Welding Journal, 1980, 59: 170s-176s.
[88] Y.J. Cho and S.H. Rhee, New technology for measuring dynamic resistance and estimation strength in resistance spot welding, Measurement Science and Technology, 2000, 11 (8): 1173-1178.
[89] F. Garza and M. Das. On real time monitoring and control of resistance spot welds using dynamic resistance signatures, Midwest Symposium on Circuits and Systems, 2001, 1: 41-44.
[90] W.L. Roberts. Resistance variations during spot welding, Welding Journal, 1951, 30: 1004-1019.
[91] S. Bhattacharya and D.R. Andrews. Significance of dynamic resistance curves in the theory and practice of spot welding, Welding and Metal Fabrication, 1974, 42: 296-301.
[92] S.A. Gedeon, C.D. Sorensen, K.T. Ulrich and T.W. Eagar. Measurement of dynamic electrical and mechanical properties of resistance spot welds, Welding Journal, 1987, 66: 378s-385s.
[93] S.C. Wang and P.S. Wei. Modeling dynamic electrical resistance during resistance spot welding, Transactions of the ASME, 2001, 123: 576-585.
[94] P.S. Wei and T.H. Wu. Effects of electrical current on transport processes in resistance spot welding, Science and Technology of welding and joining, 2010, 15 (6): 448-456.
[95] I.O. Santos, W. Zhang, V.M. Goncalves, N. Bay and P.A.F. Martins, Weld bonding of stainless steel, International Journal of Machine Tool and Manufacture, 2004, 44: 1431-1439.
[96] N. Harlin, T. B. Jones and J. D. Parker. Weld growth mechanism of resistance spot welds in zinc coated steel, Journal of Materials Processing Technology, 2003, 143–144: 448–453.
[97] J.C. Feng, Y.R. Wang and Z.D. Zhang. Nugget growth characteristic for AZ31B magnesium alloy during resistance spot welding, Science and Technology of Welding and Joining, 2006, 11: 153-162.
[98] Y. S. Zhang, J. Xu, X. M. Lai and G. L. Chen. Numerical simulation of spot welding for galvanised sheet steels, Science and Technology of Welding and Joining, 2008, 13: 192-198
[99] C. Srikunwong, T. Dupuy and Y. Bienvenu. Numerical simulation of resistance spot welding process using FEA technique, 13th International Conference on ComputerTechnology in Welding, Orlando, USA, 2003.
[100] H.A. Nied. The finite element modeling of the resistance spot welding process, Welding Journal, 1984, 63: 123s-132s.
[101] H.S. Cho and Y.J. Cho. A study of the thermal behavior in resistance spot welds, Welding Journal, 1989, 68: 236-244.
[102] D.J. Browne. Computer simulation of resistance spot welding in aluminum, part I, Welding Journal, 1995, 74: 339s–344s.
[103] Gupta and A. De. An improved numerical modeling for resistance spot welding process and its experimental verification, Journal of Manufacturing Science and Engineering, ASME, 1998, 120: 246–251.
[104] J.A. Khan, L. Xu, and Y. Chao. Prediction of nugget development during resistance spot welding using coupled thermal-electrical-mechanical model, Science and Technology of Welding and Joining, 1999, 4: 201-207.
[105] K.S. Yeung and P.H. Thornton. Transient thermal analysis of spot welding electrodes, Welding Journal, 1999, 78: 1s–6s.
[106] J.A. Khan, L. Xu, Y. Chao and K. Broach. Numerical simulation of resistance spot welding process, Numerical Heat Transfer: Part A Applications, 2000, 37: 425–446.
[107] B.H. Chang, M. V. Li, and Y. Zhou. Comparative study of small scale and‘large scale’resistance spot welding, Science and Technology of Welding and Joining, 2001, 6: 273-280.
[108] Z.G. Hou, Ill-Soo Kim, Y.X. Wang, C.Z. Li and C.Y. Chen. Finite element analysis for the mechanical features of resistance spot welding process. Journal of Materials Processing Technology, 2007, 185: 160–165.
[109] M. Wang, H.T. Zhang, H. Pan and M. Lei. Numerical simulation of nugget formation in resistance spot welding of DP590 dual-phase steel, Shanghai Jiaotong Daxue Xuebao, 2009, 43: 56-60.
[110] ASM International. Metals handbook, desk edition, 1998.
[111] C. L. Tsai, W. L. Dai, D. W. Dickinson and J. C. Papritan. Analysis and development of real-time control methodology in resistance spot welding. Welding Research Supplement, 1991, 70(12): 339s-351s
[112] D. Richard, M. Fafard, R. Lacroix, P. Clery and Y. Maltais. Carbon to cast iron electrical contact resistance constitutive model for finite element analysis, Journal of Materials Processing Technology, 2003, 132: 119–131.
[113] P. Rogeona, P. Carrea, J. Costaa, G. Sibilia and G. Saindrenanb. Characterization of electrical contact conditions in spot welding assemblies, Journal of Materials Processing Technology, 2008, 195: 117-124.
[114] S.S. Babu, M.L. Santella, Z. Feng, B.W. Riemer and J.W. Cohron. Empirical model of effects of pressure and temperature on electrical contact resistance of metals, Science and Technology of Welding and Joining, 2001, 6: 126-132.