改質的鋁鎂矽合金經熱間鍛造後對其機械性質及抗蝕性之影響

Mechanical Behavior and Corrosion Resisting Property of the Modified Al-Mg-Si Alloy after Hot Forging Process

高郁智(Yu-Chih Kao)

指導教授 ： 黃和悅

國立虎尾科技大學/工程學院/材料科學與綠色能源工程研究所在職專班/碩士(2012年)

摘要

本研究係以添加微量元素釩進行A6061熔煉的改質，鋁錠經過鍛造、旋壓及熱處理的三大製程後，探討A6061改質前後對其顯微組織、機械性質與塗裝後耐蝕性的影響。
實驗結果顯示，藉由添加微量元素釩進行熔煉的改質A6061，對於機械性質有顯著的影響，於拉伸試驗結果在輪圈各取樣部位之降伏、抗拉強度與硬度都高於未改質A6061，而因為改質A6061硬度的增加，相對地也使延伸率下降，使得旋壓過程中產生應變硬化，材料塑性流動困難，造成輪圈部分區域晶粒大於A6061的現象。
由於兩種材料之化學成份有所差異，經鹽霧試驗的結果顯示，塗裝後之改質A6061耐腐蝕性略低於未改質A6061，其主要原因是因為改質A6061的銅含量比較高，導致於改質A6061的腐蝕速度加快，使得合金的腐蝕損傷更加嚴重。
從微結構分析結果發現，A6061試樣析出相主要有Al9Si及Mg2Si兩種相，而改質A6061的試樣比A6061的試樣多析出Al3V相，因為鋁釩化合物的部分析出，這些析出物會限制晶粒成長，晶粒的細化會使硬度及機械性質有提升作用，但延展性會下降，這些結果都與本研究所得到的機械性質特性相吻合。

關鍵詞：鍛造、旋壓、應變硬化、晶粒

關鍵字

鍛造 ； 旋壓 ； 應變硬化 ； 晶粒

並列摘要

The paper describes the effects of microstructure, mechanical behavior and corrosion resisting property via forging, flow forming and heat treatment processes of modified 6061 aluminum alloy containing vanadium as a minor element.
The results indicate that the modified alloy can significantly increase ultimate tensile strength, yield strength and hardness in the different parts of aluminum wheel. Because hardness increases and ductility decreases that more easily causes plastic deformation of a modified alloy induces work hardening. Therefore, the severe localized plastic flow causes an average grain size of modified alloy is larger than A6061 alloy.
Salt spray test results show that the modified alloy has low corrosion resistance. This is because of the high Cu content in the modified alloy causes an increasing incidence of corrosion damage.
The microstructure of A6061 alloy consists of a mixture of Al9Si and Mg2Si precipitates of strengthening phases distributed at cell boundaries. Vanadium forms Al3V precipitates are found around grain boundaries in the modified alloy. Because precipitates may suppress normal grain growth, the modified alloy obtain a finer grain size typically increases tensile strength and hardness but decreases ductility.

Keywords：Forging、Flow forming、Work hardening、Grain

並列關鍵字

Forging ； Flow forming ； Work hardening ； Grain

參考文獻

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