Development of a Computer Code for the Interpretation of Results of Hot Plane Strain Compression Tests.

Kim

Archives of Metallurgy and Materials

2017

The hot deformation behavior of a heavy micro-alloyed high-strength low-alloy (HSLA) steel plate was studied by performing compression tests at elevated temperatures. The hot compression tests were carried out at temperatures from 923 K to 1,223 K with strain rates of 0.002 s −1 and 1.0 s. A long plateau region appeared for the 0.002 s -1 strain rate, and this was found to be an effect of the balancing between softening and hardening during deformation. For the 1.0 s -1 strain rate, the flow stress gradually increased after the yield point. The temperature and the strain rate-dependent parameters, such as the strain hardening coefficient (n), strength constant (K), and activation energy (Q), obtained from the flow stress curves were applied to the power law of plastic

Section: Activation Energy Measurement For the Micro-alloyed Hsla Steelmentioning

confidence: 99%

Compressive Deformation Behavior of Thick Micro-Alloyed HSLA Steel Plates at Elevated Temperatures

Kim

Archives of Metallurgy and Materials

2017

Archives of Metallurgy and Materials

“…Identification of the microstructure evolution model using two-step tests requires an accurate evaluation of the flow stress in the second step. Therefore, an advanced flow stress model proposed in [11] and published also in [12] was used:…”

Section: Rheological Modelmentioning

confidence: 99%

Accounting for the Inhomogeneity of Deformation in Identification of Microstructure Evolution Model / Niejednorodność Odkształcenia W I Dentyfikacji Modelu Rozwoju Mikrostruktury

Szeliga¹,

Kuziak²,

Kopp³

et al. 2015

Self Cite

The paper deals with the problem of identification of microstructure evolution model on the basis of two-step compression test. Classical interpretation of this test assumes uniform fields of strains, stresses and temperatures in the deformation zone and calculates the coefficients in the model on the basis of force measurements in the second step. In the present paper the inverse approach was applied. Finite element (FE) simulations of the compression test were performed and local values of microstructural parameters were determined accounting for the inhomogeneity of deformation. Objective function was formulated as the Euclid norm for the error between measured and calculated forces for various interpass times. Coefficients in the microstructure evolution model were determined by searching for the minimum of the objective function. Optimized model was validated in simulations of plane strain compression tests.

Modelling Simul. Mater. Sci. Eng.

“…Traditionally, the material is characterized by several tension, compression or torsion tests at elevated temperatures and different strain rates, see, e.g. [2][3][4][5]. One drawback with isothermal tests is the increase of unwanted phases for certain test temperatures and durations.…”

Section: Introductionmentioning

confidence: 99%

Material parameter estimation for boron steel from simultaneous cooling and compression experiments

Åkerström

Wikman

Oldenburg

2005

In order to increase the accuracy of numerical simulations of the hot stamping process, reliable material data is crucial. Traditionally, the material is characterized by several isothermal compression or tension tests performed at elevated temperatures and different strain rates. The drawback of the traditional methods is the appearance of unwanted phases for some test temperatures and durations. Such an approach is also both time consuming and expensive. In the present work an alternative approach is proposed, which reduces unwanted phase changes and the number of experiments. The isothermal mechanical response is established through inverse modelling of simultaneous cooling and compression experiments. The estimated material parameters are validated by comparison with data from a separate forming experiment. The computed global response is shown to be in good agreement with the experiments.