Study On Anisotropic Strengthening Behavior Of DC04 Steel Sheet And Evolution Rule Of Subsequent Yield Loci

As for anisotropic strengthening behaviour,aimed at describing it in an intuitive and accurate way,a calculation model was proposed and analysed.The main content includes:Taking DC04 as an example,rectangular sheet metal was pre-stretched by 3.3%,6.6% and 9.9% along different directions in plane.Then the test specimens were cut from the sheets pre-stretched and deformed in uniaxial tesnsile test and compression test,which produced test results about tensile yield strength and compression yield strength in rolling direction and transverse direction.It is worth noticing that a special fixture device was adopted during experiment to make sure that the specimen may not lose stability during compression test.With variation calculated,DC04 strengthening behaviour and rules were analysed.A strengthening calculating model was proposed,which considered the variation of yield stress deviator as the dependent variable,based on test data and the method applied by crystalline plasticity theory.The model presumed that yield strength variation in anisotropy principal axis may meet a certain relationship with plastic strain in all directions and it was established by introducing the strengthening coefficient.The yield stress variation could be viewed as sum of contributions from strain in different directions,which could be expressed in quadratic function.After simplification,model parameters were affirmed for DC04 cold rolling steel sheet.Verification was conducted with data from 15 degree angle and the results showed that this model could offer a relatively accurate calculation and description about anisotropic sheet strengthening.Subsequent discrete-type yield loci were predicted with calculation value in 0 degree and 90 degree and their variation trend was analysed.It has been achieved that the interpolation nodes could be ascertained in a simple and fast method during establishment of discrete-type subsequent yield loci with the model proposed,with taking mutual influence between different directions into account.