复杂应变率敏感性铝合金流变行为的表征

Characterization on flow behavior of complex strain rate sensitivity aluminum alloy

以NUMISHEET 2016 BM3中5系铝合金AA5086-H111为研究对象,建立其准静态温拉伸流变应力的本构模型。该材料在室温状态下的流变应力表现为负应变率敏感性;150℃时,随着应变率增加,由负应变率敏感性变为正应变率敏感性;240℃时为正应变率敏感性。针对传统指数型应变率相关项是一种单调函数,构成的本构模型一般用来描述正应变率敏感性的流变行为,很难表征这种复杂应变率敏感性流变行为的问题,给出了一种新的应变率相关项,并称其值为健壮系数。在不同应变率范围内,健壮系数可以表现出不同的单调性。结果表明,耦合新应变率相关项的本构模型可以较好地表征AA5086-H111在不同温度、不同应变率下的流变行为。

Taking the 5-series aluminum alloy AA5086-H111 in NUMISHEET 2016 BM3 as the object,the constitutive model of quasi-static warm tension flow stress was established.The flow stress of AA5086-H111 shows negative strain rate sensitivity at room tempera-ture,under 150℃,with the increase of strain rate,the flow stress changes from negative to positive and it shows positive under 240℃.In view of the problem that the traditional exponent strain rate dependency is a monotonous function,it is generally used to describe the flow behavior of pasitive strain rate sensitivity and it is diffecult to characterize the complex strain rate sensitivity of this material.A new strain rate dependency was proposed,and its value was defined as the robust coefficient.It is found that the robust coefficient has different monotonous under different strain rate range.The results showed that the constitutive model coupled with the proposed strain rate depend-ency can well describe the flow behavior of AA5086-H111 under different temperatures and strain rates.