In this paper we describe an experimental technique developed to measure the deformation gradients and temperature in a single hot rolling pass of an AA3004 sample that was fitted with an insert. The insert had been previously hand engraved with a 1x1 mm grid pitch and the analysis of the data digitally captured from the image of the deformed grid enabled the calculation of the components of the deformation gradient tensor. Four steel pins prevented relative motion between the insert and the rest of the sample. No detachment was observed between insert and sample after rolling. The temperature was measured during rolling using two embedded thermocouples, one close to the surface and the other in the centreline. The commercial finite element code ABAQUS was used to create a three-dimensional model of the rolling process. The recorded temperature was compared to the numerical values evaluated after tuning the heat transfer coefficient. The shape of the grid after rolling was checked against the deformed mesh using different friction coefficients in order to obtain the optimum match. The unusually large length of the insert enabled the rolling process to be stopped halfway so that a picture of the rollgap area could be obtained. This provided a partially deformed grid that represented the transient state during rolling. The experimentally determined deformation gradient in this area as well as in the steady state area agreed well with the finite-element predictions.

The grid technique is an experimental method for measuring the deformation in hot rolling. An AA3004 sample -fitted with an insert - was rolled in a single hot rolling pass at 400 oC. The insert was hand engraved with a 1x1 mm grid and the analysis of the image of the deformed grid enabled the calculation of the components of the deformation gradient tensor. In order to prevent relative motion between the insert and the work-piece, four steel pins were used; after the test no detachment was observed between insert and sample. The temperature was monitored during rolling using two embedded thermocouples, one close to the surface and the other on the centre-line of the slab. The commercial finite element (FE) code ABAQUS was used to build a threedimensional model of the rolling process. The recorded temperature was compared with the FE values evaluated after tuning the heat transfer coefficient. The FE model was run several times with different friction coefficients and the deformation gradient checked against the experimental measurement of the deformed grid in order to obtain the optimum friction coefficient. The experimentally determined deformation gradient and the measured temperature agreed well with the numerical values.

The present paper concerns the numerical prediction and experimental measurement of the distribution of strain in a plane strain compression test by means of a gridded insert. The insert was engraved with a 161 mm grid pitch and was embedded in an AA5182 sample. The tests were performed at 400uC with a reduction ratio of y20% and at a strain rate of 0 . 7 s 21. A thermocouple was used to record the temperature during the test. After the test, no detachment was observed between insert and sample, suggesting a close contact between them. The shape of the grid after deformation was analysed, and the in-plane component of the plastic strain calculated and compared with the numerical results obtained through finite element modelling of the test. In a comparison between experimental data and the results of a finite element (FE) model of the test that assumed perfect tool alignment, the fields of temperature agreed very well, while that for the in-plane component of strain was reasonable but inaccurate. However, significant misalignment of the tools was found in the experiments (a common occurrence in plane strain compression testing). When comparison was made with an FE model that included the geometry of the tool misalignment, the agreement was excellent. The paper discusses these effects and others such as the influence of 3D effects in the modelling.

In this paper we describe an experimental technique developed to measure the deformation gradients and temperature in a single hot rolling pass of an AA3004 sample that was fitted with an insert. The insert had been previously hand engraved with a 1x1 mm grid pitch and the analysis of the data digitally captured from the image of the deformed grid enabled the calculation of the components of the deformation gradient tensor. Four steel pins prevented relative motion between the insert and the rest of the sample. No detachment was observed between insert and sample after rolling. The temperature was measured during rolling using two embedded thermocouples, one close to the surface and the other in the centreline. The commercial finite element code ABAQUS was used to create a three-dimensional model of the rolling process. The recorded temperature was compared to the numerical values evaluated after tuning the heat transfer coefficient. The shape of the grid after rolling was checked against the deformed mesh using different friction coefficients in order to obtain the optimum match. The unusually large length of the insert enabled the rolling process to be stopped halfway so that a picture of the rollgap area could be obtained. This provided a partially deformed grid that represented the transient state during rolling. The experimentally determined deformation gradient in this area as well as in the steady state area agreed well with the finite-element predictions.