基于常规热轧工艺对喷射成形高镁铝合金挤压坯进行单道次大应变热轧变形,采用透射电镜(TEM)、扫描电镜电子背散射成像技术(EBSD)和X衍射(XRD)方法来分析合金微观结构,并对比研究合金的力学性能.结果表明:喷射成形高镁铝合金在热轧变形过程中,随着变形程度的增大,位错密度显著增大,位错胞、非平衡小角度晶界(LAGB)及亚晶显著增多;当热轧变形80％时,高位错密度晶粒中的小角度晶界转变为大角度晶界(HAGB),亚微米级动态再结晶晶粒大量形成,晶粒组织显著细化,合金的室温拉伸强度和伸长率分别为619 MPa和19.8％.喷射成形高镁铝合金大应变热轧变形过程中的主要强化机制是细晶强化、位错强化和固溶强化,对变形80％合金屈服强度的贡献值分别为120MPa、208MPa和158MPa,共占总强度值的94.4％.
The extrusion preform of the spray-forming Al alloy with high Mg content is hot rolled by 1-pass large deformation based on the conventional rolling technology.By transmission electron microscopy (TEM),electron backscatter diffractometry (EBSD) and X-ray diffractometry (XRD),the microstructure and mechanical properties of the alloy were investigated.The results indicate that the density of dislocation and the amount of dislocation cells,non-equilibrium low angle grain boundaries (LAGB) and subgrains increase with the increase of deformation during the hot rolling process.At the hot rolling deformation of 80％,the LAGB among the grains with high dislocation density transforms into high angle grain boundaries (HAGB),a large number of submicron dynamic recrystallization grains form,and the grains are significantly refined.The tensile strength and elongation at the room temperature of the alloy reach 619 MPa and 19.8％,respectively.The main strengthening mechanisms of the spray-forming Al alloy with high Mg content during the large hot rolling process are fine grain strengthening,dislocation strengthening and solid solution strengthening,the contribution of which to the yield strength of the alloy with 80％ deformation are 120,208 and 158 MPa,respectively,reaching 94.4％ of the total strength.
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