Crystal Structure of 316L Stainless Steel from Wire to Fiber
| Autor: | Shih-Ju Huang, 黃詩茹 |
|---|---|
| Rok vydání: | 2009 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 97 In this study, the diameter of 316L austenitic stainless steel wire was decreased from 190 μm to 179, 112, 75, 50, 34, 20, 8, and 6 μm using a multi-path cold drawing process. An intermediate heat treatment was used between cold drawing processes. The crystal structures and tensile properties of both wire and fibers were studied. First, the crystalline phases of stainless steel wire and fibers were identified using a MDI Jade 5.0. The crystal structure model of each phase was constructed based on the FIZ-FindIt software, and then loaded on MAUD (Materials Analysis Using Diffraction) to refine the monitoring X-ray diffraction profile of the sample. The Rietveld full pattern refinement method was used to analyze the quantification of each phase. The volume fraction of each crystalline phase and microstructure parameters, such as crystallite size, microstrain, and texture of each phase could therefore be obtained. The results of analyses showed that strain-induced martensite transformation occurred during a multi-path cold drawing process. The volume fraction of α''-martensite increased with a decrease in fiber diameter. There was a small portion of α''-martensite which reversed to γ-austenitic matrix during heat treatment. It is worth noting that the third crystalline phase started to form, which was identified as a sigma phase, when the diameter of the stainless steel fiber was decreased to 75 μm. The results of tensile tests showed that the ultimate tensile strength of stainless steel fiber was increased with an increase in α''-martensite. The crystallite size and microstrain of γ-austenitic phase fibers were obviously affected by the temperature of the heat treatment. However, when the temperature of the heat treatment was lower than 680 °C, the effect of heat treatment on the ultimate tensile strength and the elongation ratio of stainless steel fiber were not significance. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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