固溶處理對7B52鋁合金板材力學性能和斷裂行為的影響

固溶處理對7B52鋁合金板材力學性能和斷裂行為的影響Effect of solution treatment on mechanical properties and fracture behavior of 7B52 aluminum alloy plate

采用室溫拉伸實驗和夏比沖擊實驗測試力學性能，采用掃描電子顯微鏡(SEM)和電子背散射衍射(EBSD)分析平均晶粒尺寸、再結(jié)晶晶界比例及斷口形貌等顯微組織特征，通過分析顯微組織與斷裂行為之間的關(guān)系，研究固溶處理對7B52鋁合金板材力學性能和斷裂行為的影響。結(jié)果表明：隨著固溶溫度的升高，合金組織中Mg(Zn, Cu, Al)2四元相回溶速度、再結(jié)晶比例增加，當溫度超過480 ℃時，對合金力學性能不利；475 ℃固溶1h后，隨著時間的延長，顯微組織變化不明顯。7B52合金斷裂機制為穿晶斷裂和沿晶斷裂并存的混合型斷裂，沿晶裂紋沿著再結(jié)晶晶界擴展，富Fe/Mn的難溶第二相是發(fā)生穿晶斷裂的主要原因。

The effect of solution treatment on mechanical properties and fracture behavior of 7B52 aluminum alloy plate were investigated in this work. The mechanical properties were investigated by tensile test and Charpy impact test, while scanning electron microscopy (SEM) and Electron Back-Scattering Diffraction (EBSD) were used to characterize average grain sizes and fraction of recrystallized grain. The results show that the degree of solid solution and recrystallization increase with the solution temperature increases. When the temperature exceeds 480 ℃, the mechanical properties of 7B52 alloy is weakened. When the solution treatment at 475 ℃ and the time exceeds 1 h, the microstructure changes very little with the time prolonges. The fracture mechanism of 7B52 aluminum alloy is transgranular fracture and intergranular fracture coexist mixed fracture, and recrystallized grain boundary is the inter-granular crack behavior propagation path, and the transgranular fracture behavior is significantly affected by Fe/Mn rich undissolved second phase.

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