The effect of strain-rate on plastic anisotropy of an HSLA340 steel sheet is investigated in the present paper. Uniaxial tension tests in seven different directions are performed under three strain-rates (one in quasi-static range and two in intermediate range). Flow stress and Lankford r-value are obtained from the test data to describe the plastic anisotropy of the material. Results show that the anisotropy varies with the increase in strain-rate. To model this rate-dependent anisotropic behavior, three associated flow rule based yield functions, Hill48, Yld96, and Yld2000_2d, are employed first for each strain-rate. Though the result cannot match the test data perfectly, it still seems acceptable considering the complexity of the trend of anisotropy. Accordingly, the coefficients of these models are studied, and it turns out that all of them change with the stain-rate in a similar trend. Based on this result, a rate-effect term is introduced to the coefficients of the models to characterize the rate-effect on plastic anisotropy. Finally, two issues about the modeling work are discussed. One is calibrating the Yld96 and Yld200_2d model with the non-associated flow rule, which means the coefficients of the functions are determined by flow stress only or r-value only separately. It is found that the accuracy of the characterization is largely improved because of the increase in model coefficients. The other issue that is discussed is the modeling of strain-rate effect on the plastic anisotropy. A new strategy is considered, in which the strain-rate effects in different directions are characterized first, followed by the anisotropy description. The results of the two strategies are compared and good agreement is achieved.

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