固溶溫度對6082鋁合金顯微組織與性能的影響Effect of solution heat treatment temperature on microstructure and properties of 6082 aluminum alloy

研究固溶溫度(480~580 ℃)對6082鋁合金擠壓板材的力學性能和晶間腐蝕性能的影響規律，結合金相顯微鏡、掃描電鏡和掃描透射電鏡對影響機理進行分析。結果表明：隨著固溶溫度的升高，合金的強度先升高后下降，在520~540 ℃時達到最高值；而伸長率呈現不斷升高的趨勢；晶間腐蝕的最大深度呈現先增加后降低的趨勢。隨著固溶溫度的升高，殘留結晶相的數量逐漸減少，時效后獲得的β″沉淀強化相的尺寸更小、密度更高，晶界無沉淀析出區更窄，強度和伸長率更高；但溫度過高時，再結晶嚴重，晶粒粗大，擠壓效應消失，強度下降。固溶溫度影響再結晶和亞晶粒大小以及晶界第二相析出狀態和無沉淀析出帶寬度，進而改變晶間腐蝕擴展路徑及最大腐蝕深度。

The effect of solution heat treatment temperature on the mechanical properties and intergranular corrosion of the extruded sheets of 6082 aluminum alloy was investigated and the mechanism was discussed based on the microstructure examination by optical microscopy, scanning electron microscopy and scanning transmission electron microscopy. With the increase of temperature, the strength increases firstly to the maximum value at 520-540 ℃, then, decreases; while the elongation increases gradually; the maximum penetration depth of intergranular corrosion increases firstly, then, decreases. The increase of temperature tends to decrease the number of remnant phases and results in smaller β″ hardening precipitates with a higher density and consequently higher strength. However, too high temperatures result in coarse recrystallized grains, and thus, extrusion effect disappears and the strength decreases significantly. Solution heat treatment temperature has great effect on the recrystallization and size of subgrains, particles at grain boundaries and width of precipitates free zone adjacent to grain boundaries, therefore, changes the penetration path of IGC (Intergranular corrosion, IGC) and the maximum penetration depth.

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