Influence of a Thermo-Mechanical Treatment on the Fatigue Lifetime and Crack Initiation Behavior of a Quenched and Tempered Steel
Amin Khayatzadeh,
Jan Sippel,
Stefan Guth,
Karl-Heinz Lang,
Eberhard Kerscher
Affiliations
Amin Khayatzadeh
Institute for Applied Materials (IAM-WK), Department of Mechanical Engineering, Karlsruhe Institute of Technology, Engelbert-Arnold-Str. 4, 76131 Karlsruhe, Germany
Jan Sippel
Materials Testing, Department of Mechanical and Process Engineering, University of Kaiserslautern, Gottlieb-Daimler-Str., 67663 Kaiserslautern, Germany
Stefan Guth
Institute for Applied Materials (IAM-WK), Department of Mechanical Engineering, Karlsruhe Institute of Technology, Engelbert-Arnold-Str. 4, 76131 Karlsruhe, Germany
Karl-Heinz Lang
Institute for Applied Materials (IAM-WK), Department of Mechanical Engineering, Karlsruhe Institute of Technology, Engelbert-Arnold-Str. 4, 76131 Karlsruhe, Germany
Eberhard Kerscher
Materials Testing, Department of Mechanical and Process Engineering, University of Kaiserslautern, Gottlieb-Daimler-Str., 67663 Kaiserslautern, Germany
A thermo-mechanical treatment (TMT) at the temperature of maximum dynamic strain aging has been optimized and performed on quenched and tempered steel SAE4140H (German designation: 42CrMo4) in order to improve the fatigue limit in the high cycle fatigue (HCF) and and very high cycle fatigue (VHCF) regimes. Fatigue tests, with ultimate cycle numbers of 107 and 109, have shown that the TMT can increase both the fatigue lifetime and the fatigue limit in the HCF and VHCF regimes. The increased stress intensity factors of the critical inclusions after the TMT indicate that the effect can be attributed to a stabilized microstructure around critical crack-initiating inclusions through the locking of edge dislocations by carbon atoms during the TMT.
