Wear Prediction for Hot Forging Dies under Consideration of Structure Modification in the Surface Layer
|Autoren:||Klassen, A.; Bouguecha, A.; Behrens, B.-A.|
|Veröffentlichung:||Advanced Materials Research, Vol 1018, pp. 341-348, Sep. 2014|
Hot forging dies are exposed to a combination of high mechanical and thermal load in each forging cycle leading to abrasive wear that is one of the most frequent causes of die failure. Due to the high difference in temperature between the dies and the workpiece the surface layer material of forging dies undergoes very high thermal shock loads. High temperatures, which occur in each cycle lead to material annealing and to a softening of the material in the surface layer. However, there are die regions, like convex radiuses, where the surface temperatures exceed the austenitizing temperature. In combination with high cooling rates martensitic structures with a high hardness are generated in these regions. Both, softening as well as hardening of the tool material have a great influence on the wear resistance of dies. Nowadays a prediction of the wear amount is possible by using Finite Element Method (FEM) in combination with wear models. The approach for hot forging processes provides an input of die hardness curves under cyclic thermal load. Only by calculating die wear using this hardness curve a good accuracy of the FE result with experimental investigations is possible. Therefore relevant tests of hot forging material under typical forging load should be designed, conducted and afterwards used in the FE based wear prediction for hot forging dies.