(華南理工大學(xué) 國家金屬材料近凈成形工程技術(shù)研究中心，廣州 510640)
摘 要: 基于高分辨率三維X射線斷層掃描技術(shù)，對實際ADC12鋁合金壓鑄件疲勞試樣內(nèi)部微觀孔洞進行了檢測和重構(gòu)，對 7組不同孔隙率的試樣進行了5級應(yīng)力水平的高周疲勞實驗。三參數(shù)Weibull分析表明：隨著應(yīng)力水平升高，疲勞壽命分散性逐漸降低。采用SEM 觀察疲勞斷口，確定誘發(fā)疲勞裂紋起源的孔洞，并對其進行了分析；基于斷口表面的孔洞特征以及X射線斷層掃描重構(gòu)數(shù)據(jù)，建立了孔洞-疲勞壽命預(yù)測方程，并與實驗結(jié)果進行了對比分析。將三維X射線斷層掃描重構(gòu)數(shù)據(jù)與有限元分析相結(jié)合，計算和分析了實際微觀孔洞引起的應(yīng)力情況，為研究材料內(nèi)部實際微觀孔洞特征對性能的影響提供新的途徑。
關(guān)鍵字: 鋁合金；高壓壓鑄；微觀孔洞；疲勞；三維X射線斷層掃描；有限元分析
（National Engineering Research Center of Near-net-shape Forming for Metallic Materials,
South China University of Technology, Guangzhou 510640, China）
Abstract:The micro-porosities in fatigue specimens obtained from practical ADC12 high pressure die castings were detected and reconstructed with high resolution X-ray computed tomography technology. The high cycle fatigue tests were carried out at five stress amplitudes on seven groups of the specimens with different porosity contents. The Weibull analysis suggested less scatter of the fatigue life at larger stress condition. With the SEM observation on the fatigue fractured surfaces, the porosities initializing the fatigue cracks were identified and measured. A pore-fatigue life prediction equation was deduced with the pore characteristics from the fracture surface and 3D X-ray tomography inspection. With 3D reconstruction of tomography data and FEA method, the simulation of the stress distribution around the actual 3D pores were carried out and analyzed further. A new approach was provided to assess the effect of pores with actual 3D characteristics on casting properties.
Key words: aluminum alloy; high pressure die casting; micro-porosity; fatigue; three dimensional computed tomography; finite element analysis
