ADDITIVE MANUFACTURING OF MARAGING 250 STEELS FOR THE REJUVENATION AND REPURPOSING OF DIE CASTING TOOLING by MICHAEL ANDREW KOTTMAN Submitted in partial fulfillment of the requirements for the degree of Master of Science Thesis Advisor: Prof. David Schwam Department of Materials Science and Engineering CASE WESTERN RESERVE UNIVERSITY January, 2015 CASE WESTERN RESERVE UNIVERSITY SCHOOL OF GRADUATE STUDIES We hereby approve the thesis of Michael Andrew Kottman Candidate for the degree of Master of Science*. Dr. David Schwam Committee Chair, Advisor Dr. John J. Lewandowski Committee Member Dr. Gerhard Welsch Committee Member Date of Defense November 7, 2014 *We also certify that written approval has been obtained for any proprietary material contained therein. 2 Dedicated to my wife and parents for their steadfast love and support. 3 Table of Contents Table of Contents ...................................................................................................................4 List of Figures .........................................................................................................................7 List of Tables ........................................................................................................................ 12 Acknowledgements.............................................................................................................. 13 Abstract ............................................................................................................................... 14 Chapter 1: Introduction ........................................................................................................ 15 1.1. Die casting and die casting dies ..................................................................................... 15 1.2. Modes of failure of die cast tooling ............................................................................... 16 1.3. Tool steels ...................................................................................................................... 17 Chapter 2: Processes ............................................................................................................ 20 2.1. Gas Metal Arc Welding (GMAW) ................................................................................... 20 2.1.1. GMAW Equipment ..................................................................................................... 21 2.1.2. GMAW Parameters .................................................................................................... 23 2.1.2.1. Current and Voltage ............................................................................................... 23 2.1.2.2. Shielding Gas .......................................................................................................... 24 2.1.2.3. Travel speed ........................................................................................................... 25 2.2. Laser Hot Wire (LHW) .................................................................................................... 25 2.2.1. LHW Equipment ......................................................................................................... 28 2.2.2. LHW Process Control .................................................................................................. 29 2.2.2.1. Laser Power ............................................................................................................ 29 2.2.2.2. Wire Feed Speed and Travel Speed ....................................................................... 30 2.2.2.3. Shielding Gas .......................................................................................................... 30 2.3. Direct Metal Deposition (DMD) and Laser Engineered Net Shaping (LENS®) ................ 31 2.3.1. Equipment .................................................................................................................. 32 2.3.2. LENS® and DMD Parameters ...................................................................................... 33 2.3.2.1. Laser Input Power .................................................................................................. 33 4 2.3.2.2. Travel Speed ........................................................................................................... 35 2.3.2.3. Powder Feed Rate .................................................................................................. 36 2.4. Electron Beam Freeform Fabrication (EBF3) ................................................................. 36 2.4.1. EBF3 Equipment ......................................................................................................... 37 2.4.2. EBF3 Parameters ........................................................................................................ 38 2.4.2.1. Accelerating Voltage and Beam Current ................................................................ 38 2.4.2.2. Travel Speed ........................................................................................................... 39 2.4.2.3. Focus Current ......................................................................................................... 39 Chapter 3: Experimental Methods ........................................................................................ 40 3.1. Testing Methods and specimens ................................................................................... 41 3.1.1. Tension Testing .......................................................................................................... 42 3.1.2. Charpy V-notch and sub-sized unnotched Testing .................................................... 42 3.1.3. Hardness Testing ........................................................................................................ 42 3.1.4. X-ray radiography ....................................................................................................... 42 3.1.5. Metallography ............................................................................................................ 42 Chapter 4: Results ................................................................................................................ 44 3.1. Laser Hot Wire – Company A ......................................................................................... 44 3.1.1. Description of the method and parameters .............................................................. 44 3.1.2. Experimental Results ................................................................................................. 44 3.1.3. Discussion ................................................................................................................... 53 3.2. Laser Hot Wire – Company B ......................................................................................... 56 3.2.1. Description of the method and parameters .............................................................. 56 3.2.2. Experimental Results ................................................................................................. 56 3.2.3. Discussion ................................................................................................................... 62 3.3. GMAW - Company C ..................................................................................................... 63 3.3.1. Description of the method and parameters .............................................................. 63 3.3.2. Experimental Results ................................................................................................. 64 3.3.3. Discussion ................................................................................................................... 69 3.4. Electron Beam with Wire – Company D ......................................................................... 70 5 3.4.1. Description of the method and parameters .............................................................. 70 3.4.2. Experimental Results ................................................................................................. 71 3.4.3. Discussion ................................................................................................................... 78 3.5. DMD with Powder – Company E .................................................................................... 80 3.5.1. Description of the method and parameters .............................................................. 80 3.5.2. Experimental Results ................................................................................................. 81 3.5.3. Discussion ................................................................................................................... 86 3.6. DMD with Powder – Company F .................................................................................... 88 3.6.1. Description of the method and parameters .............................................................. 88 3.6.2. Experimental Results ................................................................................................. 88 3.6.3. Discussion ................................................................................................................... 94 3.7. Laser Engineered Net Shape – Company G Laboratory ................................................. 95 3.7.1. Description of the method and parameters .............................................................. 95 3.7.2. Experimental Results ................................................................................................