Numerical study to identify the material parameters of a damage model

• Autorzy: Schwartz R. , Castagne S. , Habraken A.

Warianty tytułu

PL

Identyfikacja parametrów modelu pękania w oparciu o analizę numeryczną

• Konferencja: 14th KomPlasTech Conference, Zakopane, January 14-17, 2007
• Języki publikacji: EN

Abstrakty

EN

In the continuous casting (CC) process, one of the reject factors is the presence of transversal cracks in the product. This type of macroscopic damage is expected to be due to the process loading in the bending and unbending area of the CC line. At this stage, the material looses a part of its ductility because of the temperature range[1] and some intergranular cracks are expected to appear. In order to study this damage, a 2D model was developed[2]. It models the intergranular crack at the mesoscopic level: the grains are meshed by solid elements and the grain boundaries are interface elements where sliding and decohesion can happen[3]. These mechanisms are predicted according a damage law relying on the creep and diffusion of voids. A representative cell is meshed according microscopic analysis telling the grain size and shape. Already validated for a microalloyed steel with C level < 0.1 wt% this model must be extended to peritectic and stainless steels. The first step is to identify the model parameters for these grades. As a preparation work, the type and the quantity of hot tensile tests required to be able to identify a single set of parameters for the damage law must be determined. So, simulations of hot tensile test of notched samples are needed. The computed stress and strain history is applied on the representative cell and the moment of rupture is determined in function of the input parameters. Thanks to inverse modelling, the parameters of the damage law are adapted in order to get one single set of parameters with only two different geometries of notch and two different strain histories.

PL

W wyniku obciążenia i gięcia materiału w procesie ciągłego odlewania pojawiają się defekty makroskopowe w formie poprzecznych pęknięć. W celu symulacji procesu pękania międzyziarnowego opracowano model 2D w mezoskali dla stali mikro skopowych, gdzie zawartość węgla nie przekracza O.1% wagi Celem niniejszej pracy jest rozszerzenie możliwości modelu w celu uwzględnienia stali perytektycznych i nierdzewnych. Aby określić parametry reologiczne dla poszczególnych materiałów przeprowadzono testy rozciągania na gorąco. W pracy wykorzystano symulacje MES z podłączoną komórką reprezentującą materiał w skali mezo. Do określenia parametrów modelu pęki nią posłużyła metoda analizy odwrotnej inverse.

Słowa kluczowe

EN

hot tensile test; continuous casting; steel; hot ductility; transverse cracking

• Wydawca: Wydawnictwa AGH
• Czasopismo: Computer Methods in Materials Science
• Rocznik: 2007
• Tom: Vol. 7, No. 2
• Strony: 237--242
• Opis fizyczny: Bibliogr. 10 poz., rys.

Twórcy

autor

Schwartz R.

autor

Castagne S.

autor

Habraken A.

• University of Liege, ArGEnCo Department, MS2F Division, Chemin des Chevreuils, 1 4000 Liege, Belgium

Bibliografia

• Ashby, M.F., 1972, Boundary defects and atomistic aspects of boundary sliding and diffusional creep, Surf. Sci., 31, 498-542
• Brimacombe, J.K., Sorimachi, K., 1977, Crack formation in the continuous casting of steels, Metallurgical Transactions B, 8 (3), 489-505
• Castange, S., Remy, M., Habraken, A.M., 2003, Development of a mesoscopic cell modelling the damage process in steel at elevated temperature, Key. Eng. Mater., 223, 145-150
• Castagne, S., Talamona, D., Habraken, A.M., 2006, A damage constitutive law for steel at elevated temperaturę, IJFP, accepted
• Mintz, B., Yue, S., Jonas, J.J., 1991, Hot ductility of steels and its relationship to the problem of transverse cracking during continuous casting, Int. Mater. Review, 36(5), 187-217
• Needleman, A., Rice, J.R., 1980, Plastic Creep Flow Effects in the Diffusive Cavitation of Grain Boundaries, Acta Metallurgica, 28, 1315-1332
• Onck, P., van des Giessen, E., 1999, Growth of initially sharp crack by grain boundary cavitation, J. Mech. Phys. Solids, 47(1), 99-139
• Pascon, F., Cescotto, S., Habraken, A.M., 2005, A 2.5D finite element model for bending and straightening in continuous casting of steel slabs, Int. J. Numer. Meth. Engng, 1, 1-34
• Suzuki, H., Hishimura, S., Imamura, J. and Nakamura, Y., 1984; Embrittlement of steels occurring in the temperature range from 1000 degrees-C to 600 degrees-C, Transaction ISIJ, 24(3), 169-177
• Tvergaard, V., 1984, On the creep constrained diffusive cavitation of grain boundary facets, J. Mech. Phys. Solids, 32(5), 373-393