轧制工艺对AZ31B镁合金薄板组织与性能的影响

研究了轧制温度和轧制速度对AZ31B镁合金薄板微观组织演变和力学性能的影响。结果表明,轧辊加热有利于镁合金薄板成型;AZ31B镁合金在低温或低速轧制时薄板纵向组织为大量的切变带,切变带区域包含大量孪晶组织,横向组织为含极少量孪晶的等轴晶组织;在轧制温度为400℃和轧制速度为16m/min轧制时,由于动态再结晶,横纵截面组织均为等轴晶。AZ31镁合金薄板的最佳轧制制度为轧辊温度为70℃、轧制温度为400℃、轧制速度为6m/min,此工艺轧制的薄板横向抗拉强度、屈服强度和伸长率分别为350MPa、300MPa和12%,纵向为345MPa、290MPa和11.2%,纵向与横向性能差别明显减小。

Effect of rolling process on microstructure and mechanical properties of AZ31 magnesium alloy sheet

The effects of rolling temperatures and rolling speeds on microstructure and mechanical properties of AZ31 magnesium alloy sheets were investigated.The experimental results show that heating the rollers is benefit of formability of AZ31B magnesium alloy sheets.The longitudinal microstructure of AZ31B magnesium alloy sheets is composed of a large number of shear bands at low rolling temperature and with low rolling speed,and twins are piled up in the shear bands.However,the transversal microstructure consists of equiaxed crystals with a small amount of twins.The longitudinal and transversal microstructure of AZ31B magnesium alloy sheets rolled at 400 ℃ with the rolling speed of 16 m/min is composed of equiaxed crystals without twins due to dynamic recrystallization.The optimum rolling process is obtained based on the experiment,which is the rollers temperature of 70 ℃,rolling temperature of 400 ℃ and rolling speed of 6 m/min.The longitudinal and transversal mechanical properties of AZ31B sheets rolled by the best rolling process are σb = 345 MPa,σ0.2 =290 MPa,δ = 11.2% and σb =350 MPa,σ0.2 =300 MPa,δ = 12.0%,respectively,and anisotropy of mechanical properties of the rolled sheets is reduced markedly.