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Grain Growth Kinetics in Steels

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Grain Growth Kinetics in Steels Project Number: RDS 21381 Grain Growth Kinetics in Steels A Major Qualifying Project Report Submitted to the Faculty of the WORCESTER POLYTECHNIC INSTITUTE In partial fulfillment of the requirements for the Degree of Bachelor of Science in Mechanical Engineering Submitted by: Erik Khzouz ________________ Date: April 28, 2011 Approved: __________________________ Professor Richard D. Sisson Jr. Abstract The effects of temperature and time on the grain growth kinetics of selected steels have been experimentally determined. The steels examined are 1045, 4140, 4340, 8620, 9310 and 52100. Samples were heat treated at temperatures ranging from 850°C to 1050°C in increments of 50°C and held for 30 minutes, 2, 4, and 9 hours. Using the standard ASTM test methods to measure grain size it was found that grain growth exhibited parabolic behavior and the activation energy for grain growth ranged from 175.2 to 353.4 KJ/mol. II Acknowledgements I would like to thank Professor Richard D. Sisson Jr. for his advice and guidance throughout the duration of this project. I would also like to thank Dr. Boquan Li, Adam Sears for their assistance in ensuring that I had the necessary equipment and training to complete this project. In addition I would like to thank George F. Vander Vort for his assistance with the etchant for revealing prior austenite grain boundaries. Lastly, I would like to thank the following graduate research students: Danielle Belsito, Chun-Min Chou, Guannan Guo, Zhijia Jin, Wendi Liu, Sidath Wijesooriya and Lei Zhang for their experimental and analytical support. III Table of Contents Abstract ......................................................................................................................................................... II Acknowledgements ...................................................................................................................................... III List of Figures .............................................................................................................................................. VII List of Tables .............................................................................................................................................. VIII List of Equations ........................................................................................................................................... IX 1 Introduction ............................................................................................................................................... 1 2 Literature Review ....................................................................................................................................... 2 2.1 Heat Treatment ................................................................................................................................... 2 2.1.1 Austenitizing................................................................................................................................. 2 2.1.2 Tempering .................................................................................................................................... 4 2.2 Grain Size and Growth ........................................................................................................................ 5 2.2.1 What is Grain Growth?................................................................................................................. 5 2.2.2 Factors Affecting Grain Growth ................................................................................................... 6 2.3 Materials ............................................................................................................................................. 7 2.3.1 AISI 1045 ...................................................................................................................................... 7 2.3.2 AISI 4140 ...................................................................................................................................... 7 2.3.3 AISI 4340 ...................................................................................................................................... 8 2.3.4 AISI 8620 Steel............................................................................................................................. 8 2.3.5 AISI 9310 Steel ............................................................................................................................. 8 2.3.6 AISI 52100 .................................................................................................................................... 8 2.3.7 Material Composition .................................................................................................................. 8 3 Methodology ............................................................................................................................................ 10 3.1 Furnace Calibration ........................................................................................................................... 10 3.1.1 Temperature Mapping ............................................................................................................... 10 3.1.2 Temperature Calibration ............................................................................................................ 10 3.2 Heat Treatment Procedure ............................................................................................................... 11 3.3 Sample Preparation .......................................................................................................................... 13 3.4 Optical Microscopy Measurements .................................................................................................. 13 3.4.1 Hyen Intercept Method ............................................................................................................. 13 IV 3.4.2 Jefferies Method ........................................................................................................................ 14 4 Results and Discussion ............................................................................................................................. 17 4.1 Gain Size Evolution ............................................................................................................................ 17 4.2 Average Grain Diameters .................................................................................................................. 18 4.3 ASTM Grain Size ................................................................................................................................ 19 4.4 Effective Time ................................................................................................................................... 19 4.5 Ideal Grain Growth ............................................................................................................................ 21 4.5.1 Evaluating K and D0 .................................................................................................................... 21 4.5.2 Evaluating Activation Energy ..................................................................................................... 23 5 Conclusions & Recommendations ........................................................................................................... 25 5.1 Heat Treatment ................................................................................................................................. 25 5.2 Sample Preparation .......................................................................................................................... 25 5.3 Average Grain Size Measurements ................................................................................................... 25 5.4 Growth Kinetics ................................................................................................................................. 26 Works Cited ................................................................................................................................................. 27 Appendix 1: Isothermal Transformation Diagrams ..................................................................................... 29 Appendix 2: Sample Grinding & Polishing Procedures ............................................................................... 32 Mark V CS600 - Sectioning ...................................................................................................................... 32 Beuhler Simplimet II – Mounting ............................................................................................................ 33 Appendix 3: Sample Etching Procedures .................................................................................................... 34 Appendix 4: Jefferies Planimetric Method Calibration Studies .................................................................. 35 Calibration Study #1 ................................................................................................................................ 35 Calibration Study #2 ................................................................................................................................ 37 Appendix 5: Average Grain Diameters ........................................................................................................ 39 Appendix 6: Effective Time Results ............................................................................................................
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