Development of Electromagnetic Pulse Welding Technique for DMW

Transcription

1 Development of Electromagnetic Pulse Welding Technique for DMW P.C.Saroj (T) Accelerator & Pulse Power Division Bhabha Atomic Research Centre Trombay, Mumbai Technical Meeting on the Dissimilar Metal Welding Experiences & Lessons Learned July,2017 Headquarters, Vienna, Austria Vienna International Centre (VIC) M-Building Room M2 1

2 Outline of the Presentation 1. Introduction 2. Electromagnetic Pulse Welding Principle 3. Experimental set up & Results 4. Numerical Simulation of DMW 5. Challenges 6. Conclusions 7. Future Plan 8. References 2

3 Nomenclature Electro Magnetic Welding (EMW) Electro Magnetic Pulse Welding (EMPW) Magnetic Pulse Welding (MPW) Magnetic Pressure Welding (MPW) Magnetic Impulse Welding (MIW) Electromagnetic Pulse Technology (EMPT) Electromagnetic Pulse Metal Processing Techniques (EPMPT) 3

4 Introduction Conventional welding processes show difficulties in joining dissimilar metal combinations due to difference in M.P. In contrast; EMP welding technology allow welding between dissimilar metal by plastic deformation without melting of base metal The metallurgical bond is produced without fusion; mechanical and chemical properties of materials do not under go liquid solid transformation. Produced joint does not adversely affect the heat treatment and microstructure of metal, so the procedure does not require preliminary and post-weld heat treatment. EMW is a solid state welding; that produces a weld by high velocity impact EMW are more competitive than conventional methods in terms of Simplicity, environmental friendly and automation 4

5 Principle of EMP Welding Technology Equivalent Circuit Cross Section of Graphic depicting the Tool Coil and Work piece 5

6 Schematic of MPW Process of two tubes (Source: MPW, Manual, LISBOA-2010) 6

7 EM Technology: Potential Applications across Various Sectors Automobile Sector Lug Crimping Electrical Industry: Crimping.. Ship Building Industry Aluminum Fabrications in any Industry Dissimilar Materials Advance Core and Cladding Steel Courtesy: Trans. Am. Nucl. Soc. (USA) International Atomic Energy Agency 7

8 Experimental Setup (40kJ, 20kV) Power Supply Capacitor Bank EMM Tool EM Forming /Welding System Schematic Block Diagram EM Tool (6 Disc Coil with Field Shaper) 4 Disc Coil without Field Shaper International Atomic Energy Agency 8

9 4 Disc Coil and Field Shaper For D9/T91 Tube to SS304 Plug Weld Trial 9

10 Weld Analysis of D9/T91 tube to SS304 plug Micrograph of welded sample Casted sample Polished and etched with Oxalic acid Indicative sample of D9/T91 steel to SS304 EMW sample. 10

11 Burst Test of EM Welded Sample EM welded D9 clad to SS304 end plug, tube ruptured at TIG welded EM welded joint is also stronger than TIG welded joint, this could be due to heated affected zone. This proves the superiority of solid state high strain welding. The Sample was subjected to hydraulic pressure test using Maximator make, German test Equipment (Capacity: 400Mpa) 11

12 EM Pulse Welding of Copper tube to Soft Iron Joining of soft iron to copper proves to be very beneficial for several industrial applications. Conventional fusion welding method, by applying the thermal energy to melt these two metals and fuse together leads to unreliable weld due to vast difference in melting points. It is difficult to remove oxide layer on Al. Alloying of the two metals creates a brittle inter-metallic compound that is mechanically and electrically poor in quality. 4 Disc EM coil Dimension (AL tube) Measure (mm) Dimension (Cu Disc) Measure (mm) OD 48 OD 44 ID 44 Length 25 Thickness 2 Stand off 2 Weld length 20 Weld length 20 Geometry and Dimensions Current waveform Pressure on Copper tube 12

13 Test Results of Cu tube to Soft Iron weld Helium Leak test Samples of copper tube and soft iron Pull out test Optical Micrograph of interface International Atomic Energy Agency Interface penetration of copper and iron using XRD 13

14 Experimental Setup for Flat Sheet Welding Source: APPD, BARC, Bombay & Dr. Sachin D. Kore, IIT Guwahati SPARK GAP Upper Coil Plate s Lower Coil LOAD COILS CAPACITOR International Atomic Energy Agency 14

15 EM Welded Samples Test Results Al to Al-Li Al to SS Al to AZ 31 International Atomic Energy Agency Cu to SS 15

16 Numerical Simulation Test Results Min Velocity of Impact for Al-SS At 5kV At 8kV At 9kV Rebounding Effect Simulations were performed at various applied voltages,1 kv to 9 kv. There is an increase in the depth of deformation with the increase in applied voltage. Work piece was not getting full deformation at 5kV. This may be due to non-uniform distribution of magnetic field and increased stiffness of the work piece. Depth of forming was increasing from 35 mm at 5kV to 44.7 mm at 8kV.At 9kV, the depth of deformation decreases, this is due to the rebounding effect. International Atomic Energy Agency 16

17 Depth of deformation Vs applied voltage International Atomic Energy Agency 17

18 Challenges involved Electrically Failed direct coil MSE in Be-Cu FS MSE & Failure in direct coil Mechanical & Elect properties change with increase in temperature. Increase in tempt. Magnifies the joule heating effects. Magnetic Saw effect (MSE) is due to molten metal pushed away by magnetic field, resulting in the damaged surface of the FS with saw like marks. International Atomic Energy Agency 18

19 Be-Cu Field Shaper with replaceable Copper Insert after trial 19

20 Methods to Reduce Magnetic Saw Effect (MSE) Use of material with high melting point like Tungsten/ Tantalum etc. Use of a coil of higher inner radius compared to skin depth. Complete elimination of irregularities or pre- existing cut in the inner surface of the coil. Use of liquid N 2 for cooling to reduce the MSE. Use of a Multilayer or Spiral coil to reduce the characteristic surface temperature. To over come MSE, high field zone is to be replaced by disposable Inserts viz Tantalum, Copper Tungsten, Niobium, AISI316 steel, P91, AA2014 and ETP copper. Among these Copper showed most promising results in terms of the quality of the joint. 20

21 Conclusion EM Pulse Welding of Dissimilar Metal have been demonstrated for various combinations and sizes of metals Optical Micrograph and SEM showed good metallurgical bonding. High strength Disc coil and field shapers have been developed At high field (~40T), magnetic sawing effect /deformation are seen on Field shaper Disposable field shaper at higher(>45) pulse field may be deployed In case of Flat sheet; at higher voltage, the depth of deformation decreases due to rebounding effect. 21

22 Future Plan Analysis of Failure mechanism of tool coil and mitigation technique Simulation of EMW interface under high strain rate for Dissimilar Metals Optimisation of electrical and mechanical parameters for DMW Inspection and Repair of EMW to be devised EM pulse welding seems to be a potential technique for DMW for high strength steels such as ODS steel (generation IV cladding Material) retaining its metallurgical characteristics Testing of EMW samples in reactor environment 22

23 References 1. Proceedings of the 17 th International Conference on Nuclear Engineering ICONE17, July 12-16, 2009, Brussels, Belgium ICONE Electromagnetic Pulse Technology as means of Joining Generation IV Cladding Materials, John McGinley, European Commission, JRC-ITU,Karlsruhe, Germany kv, 40 kj Electromagnetic Manufacturing Machine"; P.C. Saroj, M.R. Kulkarni, Vijay Sharma, Satendra Kumar and L.M. Gantayet, BARC Report Internal Report, kv, 40 kj Electromagnetic Manufacturing Machine for Forming and Welding applications, P.C. Saroj, M.R. Kulkarni, Satendra Kumar, et.al., Annual Welding Seminar on 23rd November 2013 organized by IIW-Mumbai branch. 4. S.D. Kore, P.P. Date, S.V. Kulkarni, Electromagnetic impact welding of aluminum to stainless steel sheets, Journal of Materials Processing Technology, Volume 208, Issues 1-3, 21 November 2008, Pages Synchronization and reliable operation of triggered spark gap switches in 40 kj, 20 kv EMM system, Saroj, P.C. et.al Page(s): , ISDEVI Copper, Iron weld techniques evaluation using helium leak rate ; Satendra * Kumar, T.K. Shah #, P C Saroj *, M R Kulkarni *, and Archana Sharma *. * APPD, #L&PTD, BARC, Trombay, Mumbai; National Symposium on vacuum techniques & applications to electron beam (IVSNS-2015) paper No. 15, November Metallurgical & Mechanical Testing of Electromagnetically welded copper and Iron sample; Satendra Kumar, M R Kulkarni, P C Saroj et al;14th Asia Pacific Conference on NDT Mumbai, India (apcndt2013.com)., page No. 23

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