August 2020 Volume 2

FORGING RESEARCH

Acknowledgements ..................................................................................................................................................................................xxi Glossary ...................................................................................................................................................................................................xxii 1.0 Introduction .......................................................................................................................................................................................1 2.0 Background ........................................................................................................................................................................................4 2.1 Strengthening Mechanisms ........................................................................................................................................................4 2.1.1 Strengthening Overview ...................................................................................................................................................4 2.1.2 Solid Solution Strengthening ............................................................................................................................................5 2.1.3 Precipitation Strengthening ..............................................................................................................................................5 2.1.4 Grain-Boundary Strengthening . ......................................................................................................................................11 2.1.5 Dislocation Strengthening/Work Hardening/Strain Hardening ......................................................................................12 2.2 Composition and Alloying..........................................................................................................................................................14 2.2.1 BAMPRI, Meadville Forging Company, TIMKENSTEEL Steel Company Composition . ............................................14 2.2.2 Carbon .............................................................................................................................................................................17 2.2.3 Vanadium ........................................................................................................................................................................19 2.2.4 Titanium ..........................................................................................................................................................................19 2.2.5 Nitrogen ...........................................................................................................................................................................22 2.2.6 Vanadium and Titanium Precipitates: Solubility and Influences ......................................................................................24 2.2.7 Chromium, Molybdenum and Manganese ......................................................................................................................34 2.2.8 Silicon, Phosphorous and Aluminum ...............................................................................................................................37 2.3 Austenite Conditioning ..............................................................................................................................................................39 2.3.1 SV Parameter ....................................................................................................................................................................39 2.3.2 Recrystallization and Temperatures T 5 and T 95 ................................................................................................................41 2.3.3 Grain Coarsening and Temperature T GC .........................................................................................................................43 2.3.4 Deformation and Forging Passes ......................................................................................................................................46 2.4 Cooling and Transformation ......................................................................................................................................................49 2.4.1 Cooling Rates ...................................................................................................................................................................49 2.4.2 RCF Cooling Schedules ...................................................................................................................................................52 2.5 Relation to FIERF RCF Project ..................................................................................................................................................56 2.5.1 Austenite Conditioning ....................................................................................................................................................56 2.5.2 Cooling and Transformation ............................................................................................................................................57 2.5.3 Strengthening Employed ..................................................................................................................................................59 3.0 Statement of Objectives ......................................................................................................................................................................61 4.0 Experimental Procedures ....................................................................................................................................................................63 4.1 Microstructural Analysis .............................................................................................................................................................64 4.1.1 Optical Microscopy ..........................................................................................................................................................64 4.1.2 Scanning Electron Microscopy (SEM) .............................................................................................................................65 4.1.3 Transmission Electron Microscopy (TEM) ......................................................................................................................66 4.1.4 Grain Size Measurements .................................................................................................................................................66 4.2 Mechanical Properties ................................................................................................................................................................67 4.2.1 Tensile Testing ..................................................................................................................................................................67 4.2.2 Micro Hardness and Nano Hardness ...............................................................................................................................68 4.3 Austenitic Phase Processing ........................................................................................................................................................68 4.3.1 Initial Convection Furnace Heating Trial .........................................................................................................................68

FIA MAGAZINE | AUGUST 2020 63