退火温度对轧制变形镁锂合金组织与力学性能的影响

Effect of annealing temperature on microstructure and mechanical properties of rolled wrought Mg-Li alloy

研究冷轧(压下量75%)及150、200、250和300℃等温退火1 h后Mg-8Li-1Al-0.5Sn合金的组织演变、力学性能以及变形机理。结果发现,合金伸长率随退火温度升高先增加再降低。退火温度为200℃时,合金伸长率达到最佳,为40%,相较冷轧态,强度无弱化表现,为212 MPa,伸长率提高24.4%。合金塑性的提升主要是由于退火促进合金内α相由带条状向竹节状转变,缓解应力集中,同时促进β相发生静态再结晶和晶粒细化。此外,α相轧制织构在退火过程中发生角度偏转,保留了有利于滑移的{1010}晶面织构,也对合金伸长率的提升起到促进作用。

Microstructure evolution,mechanical properties and deformation mechanism of Mg-8Li-1Al-0.5Sn alloy after cold-rolling(deformation of 75%)and then isothermally annealed for 1 h at 150,200,250 and 300℃,respectively,were studied.The results show that the elongation increases first and then decreases with the increase of annealing temperature.When the annealing temperature is 200℃,the elongation of the alloy reaches the best,which is 40%,and compared with the cold-rolled alloy,the strength without weakening is 212 MPa,and the elongation is increased by 24.4%.The ductility of the alloy is improved mainly because that the annealing promotes the transformation ofαphase from strip to bamboo-like,alleviates stress concentration and promotes static recrystallization and grain refinement ofβphase.In addition,theαphase rolling texture is angular deflected during annealing,which retains the{1010}grain direction texture conducive to slip and promotes the elongation of the alloy.