粉末冶金高速鋼 ASP 60 是一種常用於切削工具與模具的合金材料，具備優異的機械性能。為提供其工程元件設計與開發之應用，本研究藉由準靜態壓縮與動態撞擊試驗，探討不同應變速率（1.0×10^-3 至 6.0×10^3 s^-1）與溫度（-195 °C 至 1000 °C）對 ASP 60 機械行為的影響，包含真應力–真應變曲線、加工硬化特性、應變速率敏感性、溫度敏感性與破壞機制，以及微觀結構的變化。研究結果顯示，ASP 60 在 -195 至 800 °C 的動態條件下具有超過 1400 MPa 的高強度；而在 700 至 1000 °C 的準靜態條件下，其塑流應力仍可維持 390 MPa 以上。整體而言，其塑流應力隨真應變增加而提升，隨溫度升高則呈下降趨勢；此外，相較於準靜態條件，動態變形下的材料塑流阻抗變化更為明顯。同時，實驗結果顯示在動態變形條件下，ASP 60 隨應變速率及溫度的變化，呈現不同的正向與負向的應變速率敏感性，且其轉換溫度約為 620 °C左右；然而在準靜態條件下，ASP 60 皆顯現正向應變速率敏感性。熱活化體積方面，無論在準靜態與動態條件下，其值隨著溫度升高而增加，隨真應變增加則減少。本研究亦成功應用 Zerilli–Armstrong HCP 模型準確描述 ASP 60 在正向應變速率敏感性下的變形行為。而透過光學顯微鏡（OM）與掃描式電子顯微鏡（SEM）觀察破壞形貌，發現 ASP 60 的破壞模式隨著變形條件而改變，且與巨觀之負向應變速率敏感性密切相關。此外，透過穿透式電子顯微鏡（TEM）觀察變形後的微觀組織，發現差排結構與析出物隨著應變速率與溫度改變而呈現不同的形貌，進而導致巨觀機械強度的差異。進一步分析顯示，ASP 60 之塑流應力皆與差排密度的平方根成正比。綜合以上結果，本研究提供 ASP 60 在不同變形條件下的機械性質與微觀組織特性，可作為高性能工程元件設計與實際應用的依據。

Powder metallurgical high-speed steel ASP 60 is a commercial alloy widely used in cutting tools owing to its superior mechanical characteristics. Accordingly, the study investigates the effects of strain rate (1.0×10^-3–6.0×10^3 s^-1) and temperature (-195 °C–1000 °C) on its mechanical behaviours through dynamic and quasi-static compression tests. The analysis provides insights into its true stress-strain responses, work hardening behaviours, strain rate sensitivities, temperature sensitivities, as well as fracture mechanisms and substructural evolution, which are essential for engineering component design.
The findings indicate that the flow stress exceeds 1400 MPa during dynamic deformation in a temperature range of -195–800 °C, while reaching 390 MPa at a quasi-static strain rate of 10^0 s^-1 between 700 °C and 1000 °C. The flow stress exhibits an increasing trend with true strain but decreases with rising temperature under both dynamic and quasi-static conditions, with dynamic loading exhibiting a more rapid variation in plastic flow resistance. Both the positive and negative strain rate sensitivities are observed under dynamic loading conditions with a transition temperature identified at 620 °C, while quasi-static conditions only exhibit positive sensitivity. In addition, the activation volume of the ASP 60 test samples increases with temperature but decreases with true strain in both quasi-static and dynamic deformation regimes. The plastic flow resistance of ASP 60 specimens shows varying sensitivity across different temperature ranges. The deformation in the specimens with positive strain rate sensitivity is described using the Zerilli-Armstrong HCP constitutive model.
The fractographic analysis reveals a dependence of brittle and ductile failure modes on the applied conditions, as well as the distinct mechanisms contributing to negative strain rate sensitivity. Specifically, brittle fracture is the predominant mechanism at a temperature of -195 °C under cryogenic conditions, while localized melting occurs at an elevated temperature of 800 °C. Both phenomena contribute to the observed negative strain rate sensitivity. In addition, the transmission electron microscopy analysis shows that tangled dislocation substructures are present in the deformed ASP 60 specimens. The secondary carbide precipitates are also observed in the material. These features contribute to an increase in plastic flow resistance. Moreover, flow stress and dislocation density exhibit a linear correlation. Flow stress rises in accordance with the square root of dislocation density across all test temperatures. Overall, a comprehensive understanding of the performance and the related microstructure development of powder metallurgical high-speed steel ASP 60 has been established.

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