鎂含量與安定化對5000系鋁鎂合金腐蝕與機械性質之影響

Effect of Mg Contents and Stabilization on the Corrosion and Mechanical Properties of 5XXX Series Aluminum Alloys

姜信丞(Hsin-Cheng Chiang)

指導教授 ： 李勝隆

國立中央大學/工學院/機械工程學系/碩士(2015年)

摘要

藉由微結構觀察、腐蝕與機械性質之量測，探討鎂(3-6wt%)含量與安定化退火對5000系冷輥鋁鎂合金敏化之影響，結果顯示，冷輥合金與經安定化退火之冷輥合金，兩者均無β相之析出。合金經敏化處理後，冷輥態合金之晶界呈現明顯的β相析出與腐蝕，且隨著鎂含量的增加，析出愈明顯且連續;而經安定化退火，抑制了合金敏化現象的發生，除了高鎂合金外，並未顯現嚴重之β相沿晶析出與腐蝕。
鎂原子的添加，除了增加鋁鎂合金固溶強化效果外，也降低了合金的疊差能，拉伸變形時，合金將顯現高加工硬化速率，有效抑制頸縮的發生，導致鎂含量愈高時，合金之強度與延伸率就愈高。另外，敏化處理降低了合金之鎂原子固溶強化效應，但對於加工強化效應並沒有顯著影響，所以與敏化前之機械性質相比較，其變化率將隨鎂含量增高而增大。而經安定化退火對機械性質之影響，與敏化處理相反，安定化退火降低了合金之加工強化效應，但對於固溶強化效應並沒有
影響，所以其變化率與合金鎂原子含量關係不大。

關鍵字

鋁鎂合金 ； 鎂含量 ； 安定化退火 ； β相 ； 腐蝕性質 ； 機械性質

並列摘要

With microstructure observation,corrosion test and mechanical test,explore the effect of magnesium contents(3-6wt%) and stabilization on the sensitization of 5XXX series aluminum alloys.The result indicated that neither the alloys after cold rolling nor stabilization precipitate the β-phase.After sensitization,the alloys which cold-rolled appeared obvious precipitation of β-phase.The precipitation of β-phase increased when magnesium contents increased.And the stabilization inhabited the sensitization,it didn’t occur serious intergranular precipitation of β-phase
except for the high magnesium contents.
Addition of magnesium also lower the stacking fault energy of alloys,the alloys showed high rate of strain hardening which inhibited the occurence of necking.Therefore,alloys contains higher magnesium
contents resulting in higher strength and elongation.In addition,sensitization treatment weaken the effect of solution strength of magnesium atoms,but it didn’t affect the strain hardening.Thus,the rate of change increased with magnesium contents increased when compared to the mechanical properties before sensitization.In contrast, the effect of stabilization on the mechanical properties showed the oppsite results, sensitization weaken the effect of strain hardening,but it didn’t affect the solution strength,therefore,the rate of change is unrelated to magnesium contents of alloys.

參考文獻

Susceptibility to Intergranular Corrosion of 5XXX Series Aluminum Alloys by Mass Loss After Exposure to Nitric Acid (NAMLT Test).

[DAV1] J. R. Davis and Associates, “ASM Specialty Handbook:

[DAV2] J. R. Davis and Associates, “ASM Specialty Handbook:

Aluminum and Aluminum Alloys”, ASM International Materials Park,

[DAV3] J. R. Davis and Associates, “ASM Specialty Handbook: