Modelling of microstructure evolution in hot work tool steels during service

• Autorzy: Krumphals F. , Wlanis T. , Sommitsch Ch. , Holzer I. , Sonderegger B. , Wieser V.

Warianty tytułu

PL

Modelowanie rozwoju mikrostruktury stali narzędziowych podczas obróbki cieplnej i pracy w warunkach eksploatacyjnych

• Języki publikacji: EN

Abstrakty

EN

Hot work tool steels are commonly in use as tools for manufacturing processes of metallic materials at elevated temperatures. To establish a reliable lifetime prediction of the tool, it is necessary to characterize the initial microstructure as well as its evolution during service since the material properties depend on the microstructural configuration. The investigated X38CrMoV5-1 hot work tool steel, which has a body centered cubic lattice structure, forms a distinct dislocation cell and subgrain structure, respectively. In this work a dislocation model for thermal creep using the rate theory with particular consideration of the subgrain boundary behaviour is applied [1]. The subgrains limit the dislocation movement and their diameter is a key parameter in determining the creep rate under many conditions. Prior computations using a dislocation dynamics technique show that the emergence of an organized subgrain structure results as a consequence of elastic energy minimization. The choice of a dislocation model has many advantages over phenomenological models and equations of state with variables not identified with microstructural features in hot work tool steels. For a detailed description of the dislocation density evolution under thermal and cyclic mechanical loads, the dislocation model is adapted to consider both creep and concurrent appearing of low cycle fatigue. Several impacts of different load cases on the microstructure evolution are demonstrated. Simultaneously, the influence of precipitation size evolution and distribution on dislocation movement is considered. The model is compared with experimental investigations of inelastic strains in tools used for hot extrusion applications, i.e. for both container [2] and die [3]. [1] N.M. Ghoniem et al.: "A dislocation model for creep in engineering materials", Res Mechanica 29, 197-219, 1990 [2] C. Sommitsch et al.: "Modelling of creep-fatigue in containers during aluminium and copper extrusion", Computational Materials Science 39, 55-64, 2007 [3] W. Mitter et al.: "Lifetime prediction of hot work tool steels", Lab. Report, Journal of Heat Treatment and Materials Science (HTM), 52, 1997

PL

Tematem pracy jest przewidywanie czasu pracy narzędzi w warunkach eksploatacyjnych. Końcowe własności wyrobu zależą od jego początkowej mikrostruktury oraz zmian tej mikrostruktury podczas wytwarzania. Dlatego za główny cel pracy postawiono sobie modelowanie rozwoju mikrostruktury podczas procesu obróbki cieplnej oraz pracy narzędzi w warunkach eksploatacyjnych. Modelowanie ewolucji mikrostruktury ze szczególnym uwzględnieniem kinetyki wydzieleń wykonano z wykorzystaniem pakietu MatCalc. W pracy analizie poddano stal narzędziową X38CrMoV5-1 o strukturze bcc, która tworzy wyraźną strukturę dyslokacyjną oraz podziarnową. Wykonane obliczenia numeryczne poddano również weryfikacji doświadczalnej.

Słowa kluczowe

EN

hot-work tool steels; extrusion; microstructure modelling; dislocation density evolution

• Wydawca: Wydawnictwa AGH
• Czasopismo: Computer Methods in Materials Science
• Rocznik: 2009
• Tom: Vol. 9, No. 2
• Strony: 228--233
• Opis fizyczny: Bibliogr. 10 poz., rys.

Twórcy

autor

Krumphals F.

autor

Wlanis T.

autor

Sommitsch Ch.

autor

Holzer I.

autor

Sonderegger B.

autor

Wieser V.

• Christian Doppler Laboratory for Materials Modelling and Simulation, Chair of Metal Forming, University of Leoben, Franz-Josef-Strasse 18, 8700 Leoben, Austria,

Bibliografia

• 1.  Ghoniem, N., Matthews, J., Amodeo, R., A dislocation model for creep in engineering materials, Res Mechanica, 29,1990, 197-219.
• 2.  Holzer, L, Rajek, J., Kozeschnik, E., Cerjak, H.-H., Simulation of the precipitation kinetics during heat treatment and service of creep resistant martensitic 9-12% Cr Steel, Proc. Materials for Advanced Power Engineering, Liege, 2006, 1191-1198.
• 3.  Kozeschnik, E., Sonderegger, B., Holzer, L, Rajek, J., Cerjak, H., Computer simulation of the precipitate evolution during industrial heat treatment of complex alloys, Materials Science Forum, 539-543, 2007, 2431-2436.
• 4.  Krumphals, F., Wlanis, T., Sommitsch, C., Buchner, B., Huber, D., Redl, C., Wieser, V., Creep fatigue in hot work tool steels during copper extrusion, Proc. Sixth International Conference on Low Cycle Fatigue, Berlin, eds, Portella, P.D. et al., DYM Berlin, 2008, 721-726.
• 5.  Krumphals, F., Wlanis, T., Sommitsch, C., Redl, C., Creep fatigue of multi-part container during hot extrusion of copper - Simulation and experimental comparison, Methods in Materials Science, 7, 2007,47-53.
• 6.  Mitter, W., Haberfellner, K., Danzer, R., Stickler, C., Life-time prediction of hot work tool steels, Lab. Report, Journal of Heat Treatment and Materials Science (HTM), 52, 1997,253-258.
• 7.  Orlova, A., Miclicka, K., Dobes, F., Choice of evolution equation for internal stress in creep, Materials Science and Engineering, A194, 1995, 9-16.
• 8.  Sommitsch, C., Sievert, R., Wlanis, T., Gunther, B., Wieser, V., Modelling of creep-fatigue in containers during aluminium and copper extrusion, Computational Materials Science, 39, 2007, 55-64.
• 9.  Sommitsch,  C., Krumphals,  F.,  Stotter,  C.,  Dendl,  D., -Wlanis, T., Huber, D., Wieser, V., Lifetime comparison of different hot work tool steels for extrusion tools in aluminium extrusion, Proc. ET'08-Ninth International Aluminium Extrusion Technology Seminar and Exposition, Orlando, 2, 2008, 425-436.
• 10. Weinert,   P.,   Modellierung   des   Kriechens   von   ferritisch/martensitischen  9-12%  Cr-Stahlen  auf mikrostruktureller Basis, PhD thesis, University of Technology, Graz, 2001 (in German).