November 2019 Volume 1

FORGING RESEARCH

Damage Criteria................................................................................................................................................................................11 Chapter 3 Material Characterization.................................................................................................................................................13 3.1 Compression Test (Flow Curves).................................................................................................................................................13 3.2 Shear Hat Testing........................................................................................................................................................................16 Specimen Design...............................................................................................................................................................................16 Shear Hat Results – Gleeble...............................................................................................................................................................18 Chapter 4 Mathematical Modelling Using DEFORM 3D................................................................................................................21 4.1 Material Models...........................................................................................................................................................................21 4.2 Numerical Parameters . ...............................................................................................................................................................26 Mesh Sensitivity Analysis..................................................................................................................................................................27 4.3 Boundary Conditions..................................................................................................................................................................29 Chapter 5 Forging Process Design.....................................................................................................................................................30 5.1 Flash Geometry. ..........................................................................................................................................................................31 5.2 Temperature................................................................................................................................................................................36 5.3 Effect of Friction Coefficient........................................................................................................................................................38 5.4 Ram Speed...................................................................................................................................................................................41 Chapter 6 PreformDesign.................................................................................................................................................................43 6.1 Multi-Section Cylindrical Billet. .................................................................................................................................................46 6.2 Flat Plate Billet.............................................................................................................................................................................49 6.3 Bent Cylindrical Billet.................................................................................................................................................................52 6.4 Final PreformDesign...................................................................................................................................................................56 Comparison & Selection...................................................................................................................................................................56 PreformGeometries Considered (Summary).....................................................................................................................................56 Detailed Analysis...............................................................................................................................................................................58 Results...............................................................................................................................................................................................61 Chapter 7 Conclusions &Recommendations....................................................................................................................................75 7.1 Conclusions..................................................................................................................................................................................75 7.2 Recommendations.......................................................................................................................................................................78 References..........................................................................................................................................................................................80 Appendix A: Material Models............................................................................................................................................................85 Appendix B: Engineering Drawing for Preforms...............................................................................................................................86 Appendix C: Forging Simulation Results. .........................................................................................................................................89 List of Figures Figure 2.1-1: Critical resolve shear stress of different slip system in magnesium alloys [14].................................................................3 Figure 2.1-2: Slip and twining systems in HCP magnesium alloys [14]..............................................................................................4 Figure 2.1-3: Shear hat specimen with dimensions [24].....................................................................................................................7 Figure 2.1-4 : Multiple stage forging process [35]...............................................................................................................................9 Figure 2.1-5: Surface crack prediction for the flatbread sample. [24]..................................................................................................12 Figure 3.1-1: Orientation of sample extraction for Gleeble compression test [14]...............................................................................14 Figure 3.1-2 : Compression test Gleeble 3500 [24].............................................................................................................................15 Figure 3.1-3: Flow stresses at ɛ = 1 for AZ80 &ZK60........................................................................................................................16

FIA MAGAZINE | NOVEMBER 2019 48