Low Temperature Post-Processing of Additively Manufactured 316 Stainless Steel
Open Access
- Author:
- Kidd, James
- Graduate Program:
- Mechanical Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- March 23, 2020
- Committee Members:
- Aman Haque, Thesis Advisor/Co-Advisor
Guhaprasanna Manogharan, Committee Member
Karen Ann Thole, Program Head/Chair - Keywords:
- Electrical Annealing
Additive Manufacturing
Processing
Low Temperature
Stainless Steel
Electron Wind Force
Strain induced
grain growth
Current Density - Abstract:
- Post processing has been dominated for the last few centuries by heat treatments with relatively little advancements in technology. These processes require extreme temperatures for extended periods of time. The need for high temperatures to promote mobility in materials has become a fundamental part of altering microstructures in materials. This thesis aims to challenge this idea. Post processes utilizing electricity have recently become an interest of material researchers due to observations of energy and time savings. Even though the use of electricity to affect microstructures was first realized in the 1960’s, studies have only just come out detailing how to control microstructures with a constant electrical current. Some research has hinted that this electrical annealing process does not require heat in order to achieve microstructural changes. This thesis details a unique electrical processing technique that can be done at room temperature. With a focus on austenitic stainless steel, special material properties, such as low stacking fault energy, allows for a unique microstructural characteristic such as a large number of annealing twins. Analysis is performed using electron backscattered diffraction, grain boundary misorientation plots, grain size analysis, and x-ray diffraction. This novel annealing and grain refinement process resulted in the grain size increasing by up to 74 percent for the grain growth experiments and the grain size decreasing by up to 74 percent for the refinement experiments. The results also showed significant changes in misorientation angle distributions for both grain growth and grain refinement with the average misorientation angle increasing up to 500 percent.