EW94耐热镁合金板材热拉延能力的实验研究

Experimental Investigation of Hot Deep Drawability of EW94 Heat Resistant Alloy Sheet

研究了Mg-9Gd-4Y-0.4Zr（EW94）热轧板材的高温力学性能与热拉延能力.高温单向拉伸测试了板材的力学性能、塑性应变比（R值）及应变速率敏感系数（m值）;板材在513 K拉伸时,σb保持在300MPa以上,在723 K拉伸时出现超塑性;R值为0.9～1.4,m值为0.08 ～0.32.考察了成形条件对EW94合金板材与AZ31板材差温热拉延成形能力的影响;EW94板材呈现较好的拉延能力,其极限拉延比（LDR）高达5.2,远高于相同实验装置测试的AZ31板材最大值.初始板材与成形后筒形件的织构演变的分析表明,锥面滑移的激活对筒壁集中减薄作了贡献;EW94热轧板材优异的热拉延能力是由于其相当高的流动应力温度敏感系数.

Mechanical properties and hot deep drawability of EW94 alloy sheet prepared through hot-rolling process was systematically investiaged.For this purpose,uniaxial tensile tests were conducted to investigate mechanical properties,strain rate sensitivity parameter （m-value）and plastic strain ratio （R-value）of the sheet at elevated temperatures.The sheet exhibited the high strength of more than 300 MPa at 513 K and superplasticity above 723 K.The m-value and R-value ranged from 0.07-0.32 and 0.9-1.4 respectively.Non-isothermal deep drawing tests were performed to explore the influence of technological parameters on deep drawability for EW94 sheet and AZ31 sheet.Limiting drawing ratio （LDR）of EW94 sheet reached 5.2 that is much higher than that of AZ31.Textures of the initial shect and the necking regions for post-deformed cylindrical cups were measured.It is suggested from texture analysis that the activation of pyramidal slip systems made contribution to neck of the cup wall.The excellent LDR of EW94 sheet is attributable to its relatively stronger temperature sensitivity of flow stress.