AC ve MFDC nokta direnç kaynak teknolojilerinin yeni nesil otomotiv çeliklerinin mekanik özelliklerine etkisi

Öz

Özellikle ultra yüksek mukavemetli çeliklerin kullanımı son yıllarda arttıkça, araç gövdesi, üreticileri nokta direnç kaynak ekipmanı için iki akım türü arasında seçim yapma zorluğu ile karşı karşıya kalmıştır. Bu çalışmanın amacı, alternatif akım (AA) ve orta frekans doğru akım (OFDA) güç kaynak makinelerinden elde edilen kaynaklı bağlantıların mekanik performans üzerindeki etkilerini karşılaştırmaktır. Preslenmemiş 22MnB5 ve DP600 çelik saclar arasındaki bağlantı için iki farklı kaynak ekipmanı AA ve OFDA teknolojisi kullanılmıştır. Hem AC hem de OFDA işlemi için preslenmemiş (22MnB5) ve çift fazlı (DP600) çelik arasındaki nokta direnç kaynaklı bağlantıların mikro sertlik sonuçları, çekme makası ve çapraz gerilim testleri ayrıntılı olarak açıklanmaktadır. Sonuçlara göre, OFDA teknolojisi ile elde edilen kaynaklı örneklerin kaynak metali ve ITAB bölgelerinde AA teknolojisine kıyasla nispeten daha düşük sertlik değerleri gözlenmiştir. AA teknolojisine göre OFDA teknolojisi ile kaynak yapılmış numunelerin mukavemet ve uzama değerlerinde pozitif etki gözlenmiştir. Çapraz çekme ve çekme makaslama testi sonuçları değerlendirildiğinde, OFDA teknolojisine sahip kaynaklı numunelerde %5'ten fazla iyileşme gözlenmektedir. Bu makalenin özgünlüğü hem AA hem de OFDA prosesinin preslenmemiş 22MnB5 ve DP600 arasındaki farklı bağlantının performans özelliklerine etkisini inceleyen karşılaştırmalı bir çalışma sunmaktır.

Anahtar Kelimeler

• Nokta direnç kaynağı
• Preslenmemiş 22MnB5
• DP600
• AA ve OFDA nokta direnç kaynağı

The effect of AC and MFDC resistance spot welding technology on mechanical properties of new generation automotive steels

Abstract

Usage of UHSS (ultra high-strength steels) had increased in recent years, automobile Body in White-BIW- manufacturers had faced the challenge of choosing between two types of currents for resistance spot welding equipment. The objective of this work is to compare the effects of welds obtained from both AC and MFDC (alternate current-AC- power source and medium frequency constant current one-MFDC) machines on mechanical performance. Two different welding equipment had been used for making joints between as-delivered 22MnB5 and DP600 steel sheets. The micro-hardness results, tensile shear (TS) and cross tension (CT) tests of resistance spot welded (RSW) joints between as - delivered (22MnB5) and double phase (DP600) steels for both AC and MFDC process are detailed. According to the results, comparatively lower hardness values were observed in the weld metal and heat effected zones of the welded samples obtained by MFDC technology compared to AC technology. The positive effect was observed in the strength and elongation values of the samples welded with MFDC technology according to AC technology. When the CT and TS test results were evaluated, more than 5% improvement is observed on welded samples with MFDC technology. The originality of this paper presents a comparative study of joint performance properties effect for both AC and MFDC process on dissimilar joints between as-delivered 22MnB5 and DP600.

Keywords

• Resistance spot welding
• As delivered 22MnB5
• DP600
• AC and MFDC resistance spot welding

References

1. [1] Fan DW, Kim HS, Birosca S, De Cooman BC. “Critical Review of Hot Stamping Technology for Automotive Steels”. Materials Science and Technology Conference, Detroit, Michigan, USA, 16-20 September 2007.
2. [2] Karbasian H, Tekkaya AE. “A review on hot stamping”. Journal of Materials Processing Technology, 210(15), 2103-2118, 2010.
3. [3] Gui Z, Liang ZY. “Formability of aluminum-silicon coated boron steel in hot stamping process”. Transactions of Nonferrous Metals Society of China, 24(6), 1750-1757, 2014.
4. [4] Neugebauer R, Schieck F, Polster SA, Mosel A. Rautenstrauch A. Schönberr J, Pierschel N. “Presshardening-An innovative and challenging technology”. Archives of Civil and Mechanical Engineering, 12(2), 113-118, 2012.
5. [5] Tungtrongpairoj J, Uthaisangsuk V, Bleck W. “Determination of yield behaviour of boron alloy steel at high temperature”. Journal of Metals, Materials and Minerals, 19(1), 29-38, 2009.
6. [6] Liang W, Liu Y, Zhu B, Zhou M, Zhang Y. “Conduction heating of boron alloyed steel in application for hot stamping”. International Journal of Precision Engineering and Manufacturing, 16(9), 1983-1992, 2015.
7. [7] Jiang C, Shan Z, Zhuang B, Zhang M, Xu Y. “Hot stamping die design for vehicle door beams using ultra-high strength steel”. International Journal of Precision Engineering and Manufacturing, 13(7), 1101-1106, 2012.
8. [8] Altan T, Tekkaya AE. Sheet Metal Forming-Processes and Applications, Chapter 7: Hot Stamping. Ohio, USA, ASM International publishing, 2012.

9. [9] Kondratiuk J, Kuhn P, Labrenz E, Bischoff C. “Zinc coatings for hot sheet metal forming: Comparison of phase evolution and microstructure during heat treatment”. Surface & Coatings Technology, 205(17), 4141-4153, 2011.
10. [10] Windmann M, Röttger A, Theisen W. “Formation of intermetallic phases in Al-coated hot-stamped 22MnB5 sheets in terms of coating thickness and Si content”. Surface & Coatings Technology, 246, 17-25, 2014.
11. [11] Abbasi M, Ketabchi M, Ramazani A, Abbasi M, Prahl U. “Investigation into the effects of weld zone and geometric discontinuity on the formability reduction of tailor welded blanks”. Computational Materials Science, 59, 158-164, 2012.
12. [12] Ramazani A, Mukherjee K, Prahl U, Bleck W. “Transformation-induced, geometrically necessary, dislocation-based flow curve modeling of dual-phase steels: effect of grain size”. Metallurgical and Materials Transactions A, 43, 3850-3869, 2012.
13. [13] Sun X, Stephens EV, Khaleel MA. “Effects of fusion zone size and failure mode on peak load and energy absorption of advanced high strength steel spot welds under lap shear loading conditions”. Engineering Failure Analysis, 15(4), 356-367, 2008.
14. [14] W Hou. "Methods and Systems for Resistance Spot Welding using Direct Current Micro Pulses". United States of America Patent Patent Pending, Pub No. US 2001/0036816 A1, 17 February 2011.
15. [15] Park SS, Choi YM, Nam DG, Kim YS, Yu J, Park YD. “Evaluation of resistance spot weld interfacial fractures in tensile-shear tests of TRIP1180 steels”. The Korean Welding and Joining Society, 26(6), 625-635, 2008.
16. [16] Lee HW, Kim YH, Lee SH, Lee SK, Lee KH, Park JU, Sung JH. “Effect of boron contents on weldability in high strength steel”. Journal of Mechanical Science and Technology, 21, 771-777, 2007.
17. [17] Shao J, Hou C. Resistance Spot Welding and In-Process Heat Treatment of Hot Stamped Boron Steel. University of Waterloo, Mechanical Engineering Master Thesis, Waterloo, Ontario, Canada, 2016.
18. [18] Choi HS, Park GH, Lim WS, Kim B. “Evaluation of weldability for resistance spot welded single-lap joint between GA780DP and hot-stamped 22MnB5 steel sheet”. Journal of Mechanical Science and Technology, 25(6), 1543-1550, 2011.
19. [19] Aras S, Ertan R, Özgül, G, Hande. “Investigation of mechanical properties of high strength steel welded by resistance spot welding”. Pamukkale University Journal of Engineering Sciences, 24(1), 63-68, 2018.
20. [20] Tunçel O, Aydın H. “Tensile properties of resistance spot welded ultra high strength steel usibor 1500”. IESS 2019 International Engineering and Science Symposium, Siirt, Turkey, 20-22 June 2019.
21. [21] Sejč P, Belanová J. “The effect of welding parameters on the properties of join between studs and steel sheet USIBOR Type 22MnB5”. Manufacturing Technology, 19(3), 492-498, 2019.
22. [22] Sun X, Stephens EV, Khaleel MA. “Effects of fusion zone size and failure mode on peak load and energy absorption of advanced high-strength steel spot welds”. Welding Journal, 86(1), 18-25, 2007.
23. [23] Khan MI, Kuntz ML, Zhou Y. “Effects of weld microstructure on static and impact performance of resistance spot welded joints in advanced high strength steels”. Science and Technology of Welding and Joining, 13(3), 294-304, 2008.
24. [24] Marya M, Gayden XQ. “Development of requirements for resistance spot welding dual-phase (DP600) steels part 2: statistical analyses and process maps”. Welding Journal, 84(12), 197-204, 2005.
25. [25] Oikawa H, Murayama G, Sakiyama T, Takahashi Y, Ishikawa T. “Resistance spot weldability of high strength steel (HSS) sheets for automobile”. Nippon Steel Technical Report, 395(385), 39-45, 2006.
26. [26] Kahraman N, Gülenç B. Modern Welding Technology. Ankara, Turkey, Epa-Mat publishing, 2020.
27. [27] Ma C, Chena DL, Bhole SD, Boudreau G, Lee A, Biro E. “Microstructure and fracture characteristics of spot-welded DP600 steel”. Materials Science and Engineering A 485, 334-346, 2008.
28. [28] Zhang H, Wei A, Qiu X, Chen J. “Microstructure and mechanical properties of resistance spot welded dissimilar thickness DP780/DP600 dual-phase steel joints”. Materials and Design 54, 443-449, 2007.
29. [29] Hernandez B, V. H Kuntz, M. L, Khan, M. I, Zhou Y, “Influence of microstructure and weld size on the mechanical behaviour of dissimilar AHSS resistance spot welds”. Science and Technology of Welding and Joining 13(8), 169-776, 2008.
30. [30] Pouranvari M, Marashi SPH. and Safanama DS. “Failure mode transition in AHSS resistance spot welds. Part II: experimental investigation and model validation”. Materials Science and Engineering A, 528(29-30), 8344-8352, 2011.
31. [31] Pouranvari M, Abedi A, Marashi P, Goodarzi M. “Effect of expulsion on peak load and energy absorption of low carbon steel resistance spot welds”. Science and Technology of Welding and Joining, 13(1), 39-43, 2008.
32. [32] Lin PC, Lin SH, Pan J. “Modeling of failure near spot welds in lap-shear specimens based on a plane stress rigid inclusion analysis”. Engineering Fracture Mechanics, 73(15), 2229-2249, 2006.
33. [33] Goodarzi M, Marashi SPH, Pouranvari M. “Dependence of overload performance on weld attributes for resistance spot welded galvanized low carbon steel”. Journal of Materials Processing Technology, 209(9), 4379-4384, 2009.
34. [34] Dancette S, Massardier V, Merlin J, Fabregue D, Dupuy T. “Investigations on the mechanical behavior of advanced high strength steels resistance spot welds in cross tension and tensile shear”. Advanced Materials Research, 89-91, 130-135, 2010.
35. [35] Chao YJ. “Failure mode of spot welds: interfacial versus pullout”. Science and Technology of Welding and Joining, 8(2), 133-137, 2003.