時效與溫度對鍛造、粉末冶金和顆粒強化6061鋁合金複合材料之疲勞裂縫擴展之性質探討

Effect of Temper and Test Temperature on Fatigue Crack Growth Properties of IM, PM and Particulate Reinforced 6061 Al Metal Matrix Composites

黃志成(Jui-Cherng Huang)

指導教授 ： 單秋成

國立臺灣大學/工學院/機械工程學研究所/博士(2003年)

https://doi.org/10.6342/NTU.2003.00010

摘要

本研究針對IM6061鋁合金、PM6061鋁合金與添加強化材SiC顆粒之6061複合材料，在T4與T6不同時效條件下，與不同之溫度環境25 0C、200 0C、250 0C與300 0C下，對靜態拉伸及等應力疲勞實驗與單一高峰應力疲勞實驗之破壞行為作一系列之研究，研究方法包括實驗分析、SEM之破壞機制觀察與TEM之微觀結構之分析。
在拉伸實驗部分，T4時效材料比起T6時效材料有較小之降伏強度和抗拉強度與較大之伸長率，在室溫時T6-PM鋁合金優異於T6-IM鋁合金之趨勢與T6-20%複合材料優異於T6-PM鋁合金之趨勢，在200 0C測試溫度時已大幅的降低，尤其當溫度提高到300 0C 的測試溫度之時，兩鋁合金與複合材料之間幾乎不存在差異。
在等力量疲勞裂縫生長實驗方面，不論是T4或T6時效處理，LT型態之試片比起TL型態有較佳之抗疲勞生長能力。而且兩型態試片之差異隨著溫度之增加而減少，在300 0C時，兩型態試片之間已經沒有差異了。在所有之試驗溫度中，PM鋁合金比起IM鋁合金表現較差之抗疲勞生長能力，它們的抗疲勞生長能力隨著溫度之增加而降低。從複合材料之疲勞破斷面的特徵發現在低

關鍵字

溫度 ； 疲勞裂縫生長 ； 時效 ； 高峰應力 ； 顆粒破裂 ； 介面脫開

並列摘要

The tensile, fatigue crack growth properties and overload retardation phenomenon of 6061 Al alloy fabricated by ingot metallurgy (IM), powder metallurgy (PM) routes and SiC particulate reinforced 6061 composites have been evaluated in both T4 and T6 tempers at temperatures ranging from 25 to 300 0C. In order to characterize the fracture behavior of the materials, the microstructure was observed by transmission electron microscope (TEM) and fracture surfaces of the specimens were examined with a scanning electron microscope (SEM).
At 25 0C, the PM alloy and composites possess a higher strength, higher strain hardening rate and a lower elongation than the IM alloy and PM alloy, respectively. Raising the testing temperature from 25 to 200 0C greatly reduced the advantage in strength of the PM alloy and composites over that of the IM alloy and PM alloy, respectively. At 300 0C, both alloys and composites possess similar strength.
The fatigue crack growth resistance in the TL orientation is inferior to that in the LT orientation for both alloys and composites in T4 and T6 tempers. The difference in crack growth resistance between the two orientations decreases with increasing temperature and is basically non-existent at 300 0C. Furthermore, the fatigue crack growth resistance in the T6 temper is superior to that in the T4 temper. In both alloys, fatigue crack growth resistance decreases with increasing temperature. At all temperatures, the PM alloy always has an inferior crack growth resistance as compared to the IM alloy. At low

並列關鍵字

Particulate ； Overload ； Fatigue crack growth ； Interfacial ； Temperature ； Temper

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