冷轧中间退火对LZ91镁锂合金组织与性能的影响

Effects of cold rolling intermediate annealing on microstructure and properties of LZ91Mg-Li alloys

利用硬度测试、室温拉伸、杯突试验、金相电子显微镜、扫描电子显微镜、透射电镜等手段,研究冷轧中间退火对LZ91镁锂合金组织与性能的影响。结果表明,经过中间退火后,合金发生再结晶,可以有效改善板材边裂现象。较优的中间退火工艺为200℃×1.0 h,薄板抗拉强度为224 MPa,较未经中间退火的薄板低16.1%;伸长率为24.8%,较未经中间退火的薄板升高11.2%;杯突IE值为6.23 mm,提高11.9%。未经中间退火的合金试样,其裂纹都平行于轧制方向呈直线状分布;而退火后,破裂的部位在胀形的最高点,裂纹呈散射状由膨胀中心沿着径向发散。

The effects of cold rolling intermediate annealing on the microstructure and properties of LZ91Mg-Li alloys were investigated using hardness test,tensile test,optical microscopy（OM）and transmission electron microscopy（TEM）. The results show that recrystallization occurs after intermediate annealing,and the edge cracking is improved. The optimized intermediate annealing technology is 200 ℃×1.0 h. The tensile strength of sheet is 224 MPa,which decreases by 16.1% compared with that without annealing,while the elongation is 24.8% which is increased by 11.2%,and cupping test value is 6.23 mm,increasing by 11.9%. The crack without intermediate annealing is mainly parallel to rolling direction and shows linear distribution. After intermediate annealing,the crack position is at the top of bulging and the crack grows along the radial direction from the core of bulging.