TY - JOUR A1 - Krumphals, F. A1 - Wlanis, T. A1 - Sievert, Rainer A1 - Wieser, V. A1 - Sommitsch, C. T1 - Damage analysis of extrusion tools made from the austenitic hot work tool steel Böhler W750 N2 - During hot extrusion of copper alloys, extrusion tools have to withstand cyclic thermal and mechanical loads. To enhance the service life of the tools, materials with high temperature strength are designed as well as an optimised process control is performed. To characterise the tool damage evolution during service and to improve process guiding, modelling and simulation are appropriate means. The extrusion process of copper billets at three different temperatures was simulated by an FE-program to obtain the temporal boundary conditions, i.e. stress and temperature distributions at the interface billet-liner. Those boundary conditions were used to simulate the elastic–viscoplastic behaviour of the tool steel Böhler W750 in service by means of Abaqus Standard™ v.6.8-3 software in conjunction with Z-Mat package. A lifetime rule was added in order to compute the lifetime consumption and the cycles to failure. KW - Hot work tool steel KW - Damage evolution KW - Lifetime prediction KW - Copper extrusion PY - 2011 DO - https://doi.org/10.1016/j.commatsci.2010.04.022 SN - 0927-0256 VL - 50 IS - 4 SP - 1250 EP - 1255 PB - Elsevier CY - Amsterdam AN - OPUS4-23215 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sommitsch, C. A1 - Sievert, Rainer A1 - Wlanis, T. A1 - Günther, Burkhard A1 - Wieser, V. T1 - Modelling of creep-fatigue in containers during aluminium and copper extrusion N2 - During hot extrusion of aluminium alloys, extrusion dies experience cyclic temperature changes as well as multiaxial loadings. To improve the service life of the dies, cleaner and high hot strength materials are designed as well as an optimised process control is performed. For the improvement of the process guiding and a comparison of lifetime behaviour of different hot work tool steels, modelling and simulation are appropriate means. The extrusion process has been simulated using the FE-program Deform to find the stress and temperature history at the inner diameter of the liner, i.e. the boundary conditions for the subsequent cyclic simulation of the container during service. Inelastic constitutive equations have been implemented into Abaqus Standard to describe strain hardening and time recovery effects. They include the Norton viscoplastic flow rule, thermo-mechanical isotropic hardening and two non-linear kinematic hardening laws. A damage-rate model predicts failure and thus the lifetime of the container. The procedure for the identification of material parameters for both the constitutive and the damage model is described in detail for the hot work tool steel Böhler W400 VMR (EN 1.2343). KW - Extrusion KW - Hot work tool steels KW - Creep-fatigue KW - Lifetime KW - Damage PY - 2007 SN - 0927-0256 VL - 39 IS - 1 SP - 55 EP - 64 PB - Elsevier CY - Amsterdam AN - OPUS4-14530 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -