本篇論文主要使用霍普金森試驗機在室溫(25℃)下對不同晶粒尺寸的316LVM不銹鋼進行撞擊試驗，並觀測其機械性質及微觀結構的變化。本次實驗，透過退火處理後得到兩不同大小之晶粒尺寸，分別為32μm和64μm，所採用之應變速率分別為3000s-1、5000s-1和7000s-1，再透過所得到之數據以及微觀結構(OM、TEM)進行分析，藉此了解相同的材料，不同的晶粒尺寸以及應變速率對材料塑變行為及微觀結構之影響。最後利用Zerilli-Armstronge構成方程式進行模擬，以描述316LVM不銹鋼在各應變速率、晶粒大小及塑流應力之關係，以方便未來在作為工程模擬分析之用途。
實驗結果指出，晶粒尺寸大小的不同對316LVM不銹鋼的機械性質影響相當明顯，為描述晶粒大小與塑流應力之關係，引用Hall-Patch方程式印證晶粒愈小則塑流應力愈大的結果。而隨著材料變形的應變速率提升，其塑流應力值、加工硬化率、應變速率敏感性係數皆會跟著上升，而熱活化體積則會隨著應變速率上升而下降。
在微觀方面，透過穿透式電子顯微鏡的觀測，材料在遭受撞擊後差排會糾結在一起，且差排密度會隨著應變速率上升而增加，而差排密度與塑流應力之關係可由Bailey-Hirsch type關係式來描述，此外當隨著應變速率的上升，甚至可觀測到差排環以及機械雙晶的產生。

In this study, 316LVM stainless steel was examined under different strain rates and grain sizes by using split-Hopkinson pressure bar to investigate its dynamic deformation behaviors and microstructure characteristics. Impact tests were performed under different strain rates ranging from 3×103 s-1 to 7×103 s-1 and different grain sizes of 32μm and 64μm at room temperature.
The results reveal that the mechanical properties are greatly affected by strain rates and grain sizes and the Hall-Petch equation can describe the relationship between flow stress and grain size. It is found that flow stress, work hardening rate and strain rate sensitivity all increase, but the thermal activation volume decreases with the increasing strain rate. However, at a constant strain rate, flow stress, work hardening rate and strain rate sensitivity decrease but the thermal activation volume increases with increasing grain size. Finally, the modified Zerilli-Armstrong model, which combine Zerilli-Armstrong model with Hall-Petch equation, is used to describe the deformation behavior of 316LVM stainless steel under the considered strain rate and grain size.
Transmission electron microscope(TEM) observations show that the dislocation density increases with increasing strain rate but decreases with increasing grain size. The relationship between the dislocation density and the stress can be expressed by using the Bailey-Hirsch equation. Furthermore, dislocation loops and mechanical twins are found at high strain rate.

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