冲击加载下LY12铝合金的动态屈服强度和层裂强度与温度的相关性

Temperature dependence of dynamic yield strength and spall strength for LY12 aluminum alloy under shock loading

采用可测量任意反射表面的速度干涉仪对LY12铝合金在不同初始温度条件下的动态屈服与层裂行为进行了实验研究,温度范围从室温到接近熔化温度.实验结果显示:LY12铝合金的动态屈服强度随着温度升高而快速下降,当初始温度为847K(比熔化温度低86K)时,其屈服强度仅为室温下的15%,层裂强度也随着温度升高而减小,在296—847K的实验温度范围内,层裂强度损失80%.通过实验结果与模型估算值的比较,发现ZerilliArmstrong(ZA)模型可以对LY12铝合金的动态屈服强度与温度的相关性进行较好的描述,而SteinbergCochranGuinan(SCG)模型对屈服强度的温度软化效应估计不足.对于铝基材料(包括纯铝、铝合金以及单晶铝),提出的经验公式较好地描述了归一化层裂强度与温度的相关性.

A velocity interferometer system for use with an arbitrary reflector was used to measure the free surface velocity history of LY12 aluminum alloy in a wide range of pre-heating from the room temperature approaching to the melting point, and the dependences of dynamic yield strength and spall strength on the initial sample temperature have been investigated. Experimental results indicate that the dynamic yield strength decreases rapidly with the heating temperature, and only 15% of the initial strength at room temperature is retained when heated up to 847 K （86 K lower than the melting temperature）. The measured yield strength has been compared with the Zerilli-Armstrong （ZA） model and Steinberg-Cochran-Guinan （SCG） model calculation, which points out that the ZA model could describe the dependence of the yield strength on temperature well and the SCG model has overestimated the dynamic yield strength at high temperature significantly. Decrease of the spall strength with the increase of heating temperature for LY12 aluminum alloy was observed also, and nearly 80% loss of spoil strength was determined in the present experimental temperature range of 296--847 K. An empirical formula has been proposed to normalize the dependence of spoil strength on the heating temperature, and it gives a fairly good fitting for a number of aluminum based materials, including pure aluminum, aluminum alloy and single crystal aluminum, measured in this work and by others in the literature.