FEM Modelling of the Plastic Flow Localization Induced in Metals by Surface Cracks

• Autorzy: Marek P. , Kurzydłowski K. J. , Rożniatowski K.
• Konferencja: German-Greek-Polish Symphosium on Advances in Mechanics (4 ; 09.2001 ; Pułtusk, Poland)
• Języki publikacji: EN

Abstrakty

EN

The aim of the present work is to provide a model for the influence of the surface films on the plasticity of metals. To this end Finite Element Method has been used to solve 2-dimensional plain strain problem. The effect of the film cracks on the deformation of the substrate for the specimens subjected to tensile straining has been studied using a number of models which different in the details of cracks geometry and origin as well as in the properties of both oxide film and metallic substrate. As far as the geometry is concerned, the following situations were analyzed: symmetric cracks on both sides of specimens - a) and a-symmetric crack on one side - b). For each of these two cases the crack depth has been varied in the range from 70 to 100% of the film thickness. As far as the cracks beginning is discussed the following two types of the cracks have been considered: * pre-existing cracks (existing in the film prior to the straining of the specimen), * fresh cracks (which develop during the straining). The model employed in the present study shows, that the macroscopic yielding of the specimens depends to some extent on the presence of the cracks in the surface film and is profoundly changed due to the presence of the residual stresses. The residual stresses due to the differences in the thermal expansion coefficients of the surface films and the substrates have been observed in the number of metals subjected to the annealing or surface treatment. The results reported here prove that these stresses deeply modify the flow stress of metals in the range of the micro-plasticity.

Słowa kluczowe

EN

plastic deformation; surface film; Finite Element Method (FEM)

• Wydawca: Oficyna Wydawnicza Politechniki Warszawskiej
• Czasopismo: Machine Dynamics Problems
• Rocznik: 2002
• Tom: Vol. 26, No. 4
• Strony: 69--81
• Opis fizyczny: Bibliogr. 3 poz.

Twórcy

autor

Marek P.

• Warsaw University of Technology

autor

Kurzydłowski K. J.

• Warsaw University of Technology

autor

Rożniatowski K.

• Warsaw University of Technology

Bibliografia

• Abduluyahed, A.A., Kurzydłowski, K.J., 1998, Tensile properties of 316 stainless steel strained in air and vacuum, Materials Science and Engineering, A256, 34-38.
• Zieliński, W., Kurzydłowski K.J., 2000, TEM studies of the oxide scales formed on type 316 stainless steel during annealing at 600°C in vacuum and air, Scripta Materialia, 40, 33-37.
• Kurzydłowski, K.J., et al., 1989, The effect of Boron on Discontinues Yielding of Ultrafine-Grained Austenitic Stainless Steel, Zeitschrift fur Metallkunde, 80, 469-475.