多道次温轧对AZ31镁合金组织和性能的影响

Effect of multi-pass warm rolling process on microstructure and properties of AZ31 magnesium alloy

以AZ31镁合金为实验材料,通过多道次温轧工艺,研究低温时效处理对温轧板材组织和性能的影响。结果表明:经5道次温轧后合金组织得到明显细化,从初始态38μm细化至2.2μm;在随后120~160℃时效过程中,晶粒并未发生显著长大。经低温时效处理后,合金在基本保持温轧态拉伸强度的同时,其塑性得到明显提升。由晶界强化和位错强化模型定量描述发现,经5道次温轧后合金显微硬度增量为30HV。然而随着时效温度的升高,位错强化贡献显著降低,而晶界强化由于晶粒长大不明显而几乎无显著变化。合金经160℃时效2 h后,两种主要强化机制对显微硬度的贡献为16HV。

AZ31 magnesium alloy was used as experimental material to study the influence of low temperature aging treatment on the microstructure and properties of warm rolled sheet by multi-pass warm rolling process.The results show that the alloy microstructure is remarkably refined after 5 passes of warm rolling,from 38μm in the initial state to 2.2μm,and no significant growth occurs during the subsequent aging at 120℃ to 160℃.After low temperature aging treatment,the alloy maintains the tensile strength in the warm-rolled state,and its plasticity is obviously improved.Quantitative description by grain boundary strengthening and dislocation strengthening model shows that the microhardness of the alloy increases by 30 HV after 5 passes of warm rolling.However,with the increase of aging temperature,the contribution of dislocation strengthening is significantly reduced,and the grain boundary strengthening has almost no significant change due to the inconspicuous grain growth.After being aged at 160℃ for 2 h,the contribution of the two main strengthening mechanisms to microhardness is 16HV.