PowerPoint Presentation

Modeling of the Heating Sequences of Lightweight Steel/Aluminum Bimaterial Billets for Hot Forging and Hot Hydroforging

Robert Goldstein1, Bulent Chavdar2, Lynn Ferguson31 - Fluxtrol, Inc. Auburn Hills, MI2- Eaton Corp. Southfield, MI3- Dante Solutions, Inc. Cleveland, OH

OverviewWhat is Bi-Material Forging?Heating Process RequirementsModel/Process DevelopmentModeling ResultsExperimental ValidationConclusions

What Is Bi-Material Forging/FormingBi-Material is a new lightweighting strategy to drastically reduce component weight which involves the followingStrong, steel shell that is heated to the austenitic state for deformationLightweight coreForging/Forming operations that take the component to a near net shape

Our Initial Billet DesignGoal is to form a gear for a semi-truck transmissionInitial Billet3.5 OD, 6.9 tall or 1020 steel shellAluminum coreElectron Beam Welded steel caps

Heating Process RequirementsHeating process must be fast to separate steel from aluminumInitial trials were done in the furnace and it was found that the weld seam needs to be in the austentic state prior to the aluminum melting to prevent weld seam fracture from expansion of aluminum

Induction Heating PursuedFastEfficientControllableVolumetric

Model DevelopmentRun initial models using 1-D software ELTA, with two threshold casesIdeal Thermal ContactNo Thermal Contact

Determine Power Requirements to get steel shell up to temperature Determine cool down ratesCompare with Experimental Results

Results of 1-D Simulation6 s heat, 15 s hold 350 kW power, 10 kHz, BilletsIdeal Thermal Contact No Thermal Contact

Heating Trial at Interpower

Evaluation of Preliminary ResultsThe thermal cycle most closely resembled the no thermal contact caseMaximum temperature achievedSlower cooling rateThis means that separation was achievedSome losses need to be added to compensate for conduction at bottom and radiative heat exchange from sidesWeld Seams reached austenitic temperature rapidly during the initial heating phase

Large gap must be there due to visibility of radiation from sides

If Aluminum were at this temperature (700 C plus), it would be spewing out top

Next Steps in DevelopmentDevelop 2-D ModelsElectromagnetic and Thermal Flux 2DThermal, Structural, Dimensional Movement and Stress DanteDevelop Thermal Cycles for FormingTemperature throughout wall thickness must maintain > 800 C 10 seconds after heating to allow for billet transportationValidate Process at Walker Forge

Billet Thermal Cycle2 Stages of Heating (Limit of Controls)High Power 90% for 4.2 sLow Power 20 25% for 21.8 sTemperature at End of Heating 2200 FTemperature after 5 s transport - 2040 FTemperature after 10 s transport 2000 F

Radial Temperature Distribution

Flux 2D Modeling Results

Axial Temperature Distribution

Flux 2D Modeling Results

2-D Cross-Sections

Flux 2D Modeling Results

2-D Cross-Sections

Flux 2D Modeling Results

2-D Cross-Sections

Flux 2D Modeling Results

Dante Temperature Predictions

Radial Gap Predictions

Experimental Trial with Billet

ConclusionsBi-Material Forming is a new and exciting lightweighting technologyA modeling method has been developed to simulate the multi-body processExperimental trials have validated the simulationMore development needs to be done to develop real world components using the concept