Advanced Induction Heat Treatment Technologies and Design Methods


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Advanced Induction Heat Treatment Technologies and Design Methods

  1. 1. 4th Asian Conference on Heat Treatment & Surface EngineeringADVANCED INDUCTION HEATTREATMENT TECHNOLOGIES AND DESIGN METHODS Dr. Valentin NEMKOV Fluxtrol Inc., Auburn Hills, Michigan, USA
  2. 2. Overview• Advanced induction technologies – old and new• Progress in power supplies and controls• Computer Simulation and Virtual Prototyping• Magnetic flux control• Internal inductors• Induction versus carburizing• Induction hardfacing• Induction treatment in Liquid Active Media• Coating treatment• Conclusions
  3. 3. Induction TechniqueIdeas of induction heating appeared at the endof XIX century. Many famous names must bementioned here, such as L. Foucault, N. Teslaand othersInduction Surface Hardening is 75 years old and Dr. Edwin Northruptwo men may be considered as major pioneers: (1866-1940)Dr. E. F. Northrup, USA and Prof. V.P. Vologdin,RussiaSince crankshaft hardening (1934-1935) thistechnology passed a long way with very bigachievements and continues to bring newimpressive resultsSome technologies developed or proposed in 30-50s maybe considered as advanced at presenttime such as SDF hardening. Prof. Valentin Vologdin (1881-1953)
  4. 4. Main Recent Achievements in Induction TechniqueInduction systems:• Solid-state power supplies• Control and monitoringsystemsInduction coils:• Magnetic flux controllers Minac 18/25 TWIN power supply, EFD• CNC machining InductionDesign methods:• Computer simulation• Virtual prototypingNew technologies Scan hardening, Elta program
  5. 5. Modern Power Supplies• Modern solid state powersupplies can provide anyrequired combination ofpower and frequency• Power – from 1 kW toseveral MW• Frequency – from linefrequency to 0.5 MHZ andmore (for small power)• Intelligent systems• Small dimensions• High efficiency Courtesy of EFD Induction, Inc
  6. 6. Simultaneous Dual Frequency Hardening (SDF)For contour hardening of gears and other parts of complexgeometry, special transistor power supplies were developed that cangenerate two frequencies simultaneously. Power levels may beprogrammed independently for each frequency, providing accurateresults and high process flexibility Induction hardening installation: Gear hardened by SDF Middle Frequency power 400 kW High Frequency power 200 kW Courtesy Eldec Induction U.S.A.
  7. 7. Virtual Prototyping (VP)Virtual Prototyping is the use ofcomputer models to developand test the process and/orcomponent without having tophysically build or run itVP includes detailed analysisof the problem, developmentand optimization of newconcept using modelingAt present time – EM, Thermal FEA mesh for axle scanand Structural tasks hardening with optimizedEmerging – Stresses and inductorDistortions
  8. 8. Example of Virtual Prototyping: Wheel Hub Hardening Problem:• Short coil life: 8,000 – 13,000 pieces• Difficult setup with big machine downtime, personnel time and scrap parts Typical process of wheel hub heating with “stepped” coil
  9. 9. Modeling of Part Temperature & HardnessTemperature distribution in part with Predicted hardness pattern new coil design Flux 2D program + Metal 7
  10. 10. Modeling of Coil TemperatureCopper:Copper temperature calculationis available in Flux programHeat transfer coefficientcalculated from water flow rateResults: Max coppertemperature <100°CConcentrator:Special procedure had beendeveloped for theconcentrator temperaturecalculationIt accounts for the magneticlosses, radiation and glueproperties
  11. 11. Performance and Longevity Tests• Test showed that precisehardness pattern wasreached on the 3rd part• Coil and process setupbecame easy• Lifetime was not anymorea problem. Coil heated170,000 parts and stillremained in goodconditions >170,000 cycles
  12. 12. Hardness Pattern for Axle Scannedwith Original and Optimized Coils Coil power 170 kW, Frequency 1 kHz
  13. 13. Magnetic Flux ControlMagnetic Flux control includesconcentration, shielding andfield modificationAdvantages of magnetic controllers:• Heat pattern control• Coil current demand reduction• Better use of induced power• Elimination of unintended heatingof the part or machine components• Coil parameter improvement(efficiency, power factor)Materials for magnetic control:• Laminations• Ferrites• Soft Magnetic Composites (SMC) 13
  14. 14. Composite Materials for Magnetic Flux ControlSoft Magnetic Compositesrepresented mainly by Fluxtrol andFerrotron materials, have a veryfavorable combination ofmechanical, thermal andelectromagnetic properties:• Can work in entire range ofinduction heating frequencies (upto 13 MHz)• Have excellent machinability• Can work in 3D magnetic fields• Have good magnetic properties• Have good thermal properties• May be used as structural Composite materialscomponents in the coils manufactured by Fluxtrol Inc.
  15. 15. Magnetic Permeability of Fluxtrol ProductsMaterials are quasi-linearFluxtrol A material can supportpermeability above 80 at highmagnetic loading (flux density up to Permeability vs Flux Density9000 Gs) 125 Permeability 100 FerrotronSMC work well at very challenging 75 559 Fluxtrol 50applications when properly selected 50 Fluxtrol Aand applied: 25 0• Material must be selected with 0 3000 6000 9000 12000account for orientation due to Flux Density, Gsanisotropy• Good thermal management by Information about Fluxtrolmeans of application to the coil with and Ferrotron propertiesthermally conductive glue or by means and application is availableof separate cooling on site 15
  16. 16. Examples of Coils with Composite Flux ControllersCoil for Al part brazing with Fluxtrol Internal coil with Fluxtrol controller A controller
  17. 17. Selected Induction Technologies
  18. 18. Induction Instead of CarburizingExample:Initial process withfurnace carburizing:• Masking of the part• Carburizing for about 80 hrs to a depth of 8 mm• Demasking• Furnace hardening• Cryogenic treatment• Tempering• Grinding to correct Scan hardening of an internal surface of distortions a big steel component (750 kg) New process: Magnetic concentrator strongly reduces the • Induction scan hardening coil current (2 times) and therefore size of • Furnace/induction tempering the transformer and other equipment • Final grinding
  19. 19. Induction Hardfacing/CladdingThe goals are to increase:- Hardness- Wear resistance- Chemical resistancePowders compositions:•C 2.5 – 7.0 %• Cr 20 – 40 %• Mn < 15%• Ni 0.5 – 5 %• Si 1 – 2 %• Others – Cu, B, W, MoTypical hard layerthickness – 0.5 - 2 mm Courtesy Freal & Co
  20. 20. MicrostructuresHard LayerSubstrate 155 mkm 30 mkm Low porosity and Excellent transient zone inclusions Courtesy Freal & Co
  21. 21. Hardfacing of Harrow DiscsLife time is 2-3 times longerthan for traditionally treated discs Harrow disc with hardfaced teeth Courtesy Freal & Co
  22. 22. Induction Hardfacing Process Magnetic controllers from Fluxtrol 50 for temperature distribution control Courtesy Freal & Co
  23. 23. Induction Hardfacing Installation 4 3 1 5 2 Versatile automatic hardfacing installation 60 kW, 66 kHz1 – Generator, 2 – Controls, 3 – Heat Station4 – Cooling System, 5 - Machine Courtesy Freal & Co
  24. 24. Thermo-Chemical Processing with Induction HeatingInduction gascarburizing is a wellknown but not usedprocessCombination ofinduction processing inliquid media, proposedby Prof. Saveliy Gugel,provides many newopportunities Courtesy Sanova LLC
  25. 25. Induction Treatment in LAM Vapor blanketInduction carburizing in liquidactive media (LAM) occurs at LAM Thigh temperature and veryhigh concentration (potential) xof carbon or other elements(B, N, etc.)Process is very flexible due Insulationto many variables: LAMcomposition, temperaturevariation on the part surfaceand subsequent heat treating Chamberprocess parameters Courtesy Sanova LLC
  26. 26. Variety of Structures on Steel Surface Ledeburite (a) Austenite (b) Martensite (c) Courtesy Sanova LLC
  27. 27. Steel AISI 8620 after TreatmentSteel:C 0.18/0.23; Cr 0.4/0.6; Mn0.7/0.9; Mo 0.15/0.25; Ni0.4/0.7; Si 0.15/0.35 50HRcExample of processing:- Carburizing 35 min - 1220 C- Recrystallization Cooling 0.5 min- Heating to 870 C and soaking, Fine M + F P+A 4 min- Hardening in LAM, 0.5 min 45-25 HRc- Self-tempering, 2.5 min 63-67 HRc Case depth is around 2 mm Courtesy Sanova LLC
  28. 28. Example of Ti Alloy TreatmentTreatmentincreasedstrength, wearand fatigueresistanceErosionresistanceincreased morethan 3 times Microstructure of Ti6Al4V (x100) and micro-hardness curve after treatment in LAM for 20 min Courtesy Sanova LLC
  29. 29. Installation for Processing 2 11 – Power supply2 – Treatment block 33 – Control panel Courtesy Sanova LLC
  30. 30. Electromagnetic WiperInduction heating is widely used for Preheating and Remeltingof strips and wires in galvanizing and galvannealing processes.One new application – removal of excess of the molten coating(zinc) from the parts. Electrodynamic forces are used here. F Courtesy Netshape Cast, USA
  31. 31. Conclusions• There are many new applications of induction heating in heat treating and surface engineering• Some old technologies found new life due to new environmental and technical requirements and advanced techniques• Advanced design methods based on computer simulation may be called “Virtual Prototyping”• Treatment in LAM, hardfacing, coating remelting and “brushing” are the examples of new induction technology in surface engineering
  32. 32. Acknowledgement The author thanks CHTS and Fluxtrol Inc. for presentation support Michigan, USA Beijing,