| Summary: | 碩士 === 國立臺灣大學 === 材料科學與工程學研究所 === 95 === Hot-dip galvannealed sheet steel (GA) is a widely utilized source for automotive body panels and parts due to its exceptional corrosion resistance properties. Although the alloying process and lubrication during working improves the formability of the sheet steel, for large and more complex parts, a more developed lubricant film coating is required during molding and working processes. The processing and properties of GA lubricant film coating will be the focus of this study. Commercial sheet steels from industry such as NSC, NKK, SMI, and Chemetall are analyzed to discover possible processing solutions and conditions, and further seek possibility of developing a process of its own. The experiments included modeling of NSC and 16 possible Chemetall processing conditions. The following analysis included Inductively Coupled Plasma – Atomic Emission Spectrometer (ICP), Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), Glow Discharge Spectrometer (GDS), X-Ray Fluorescence Spectrometer (XRF), surface tension measurements, adhesion tests, and friction coefficient measurements. Some of the findings include: NSC generalized as a chemical bath process, NKK a nickel electro deposition process, SMI and Chemetall are surface rolling processes. In the modeling conditions of NSC, excess amount of permanganate will remain on the surface of sheet steel. Thus, chemical bath process with rinse has better results than the rolling counterpart with bake. On the other hand, the modeling with metallic powder-mixed solution comes most similar to the Chemetall process. The addition of anion will also become mixed within the lubricant film coating, which have positive effect on failure resistance however will also increase the friction coefficient of the coating.
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