預(yù)變形對超高強(qiáng)鋁合金擠壓材組織性能的影響

預(yù)變形對超高強(qiáng)鋁合金擠壓材組織性能的影響Effect of pre-deformation on microstructure and properties of ultra-high strength aluminum alloy extrusion materials

采用硬度與電導(dǎo)率測試、拉伸試驗、晶間腐蝕和剝落腐蝕試驗以及X射線衍射(XRD)、掃描電鏡(SEM)、電子背散射衍射(EBSD)分析等方法研究預(yù)變形對Al-12.45Zn-3.56Mg-1.12Cu-0.21Zr-0.0553Sr鋁合金擠壓材組織與性能的影響。結(jié)果表明：該合金在(121 ℃, 24 h)時效制度下，預(yù)變形處理能有效引入位錯，位錯密度從0.197×10-14 m-2提高到1.156×10-14 m-2；同時，由于位錯對強(qiáng)度的貢獻(xiàn)高達(dá)58.7 MPa。根據(jù)EBSD分析，經(jīng)預(yù)變形處理后，合金的低角度晶界所占比例為66.2%，比未經(jīng)預(yù)變形處理的合金提高12.6%，平均晶界角度值降低3.894°，平均晶粒尺寸增長6.396 mm。預(yù)變形能夠明顯提高合金的抗晶間腐蝕性能(最大晶間腐蝕深度由222.1 mm降低至165 mm)，對剝落腐蝕性能的影響不明顯。

The effects of pre-deformation on microstructure and properties of Al-12.45Zn-3.56Mg-1.12Cu-0.21Zr- 0.0553Sr ultra-high strength aluminum alloy extrusion materials were studied by means of micro-hardness tester and electrical conductivity test, tensile test, intergranular and exfoliation corrosion experiment, X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron back-scattered diffraction (EBSD) analysis. The results show that in the aging system at 121 ℃ for 24 h, the pre-deformation can effectively introduce dislocations,the dislocation density increases from 0.197×10-14 m-2to 1.156×10-14 m-2, and the strength reaches up to 58.7 MPa because of the dislocation contribution.Based on EBSD analysis, after pre-deformation treatment, the low angle grain boundary proportion (66.2%) of the pre-deformation alloy increases by 12.6% than that of the underformed alloy, the mean misorientation value reduces 3.894°, and the average grain size increases by 6.396 μm. The pre-deformation treatment can significantly improve the intergranular corrosion resistance properties (the maximum intergranular corrosion depth reducing from 222.1 μm to 165 μm), but little improvement on exfoliation corrosion performance.

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