Charakterisierung der Gefügeentwicklung und Umformbarkeit bei der Halbwarmumformung von Stählen

Translated title of the contribution: Characterization of the microstructural development and formability in warm forming of steels

Georg Kromoser

Research output: ThesisDiploma Thesis

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Abstract

The term warm forming means a forming in the temperature range between conventional cold and hot forming. The technique tries to combine the advantages of the two processes and at the same time to circumvent the disadvantages by using the best forming temperature. Compared to cold forming, the forming force can be considerably reduced, and the accuracy of the parts produced can be increased compared to the hot forming process. In literature research, the state of the art in the production process of warm forming was investigated. In the course of this a patent search took place. The experimental investigations were carried out on the materials 42CrMo4 and 20MnCrMo7, which are used for forging applications. The experimental plan was drawn up on the basis of the TTT and TTA diagrams of the corresponding materials, and in view of real process control during hot forming. The TTT and TTA diagrams were calculated using the software JMatPro. In order to characterize the workability in the investigated temperature range of the selected materials, upsetting tests were carried out with a Thermo-Mechanical-Treatment Simulator. For the experiments, various heating procedures were used to test the influence of the heating process on the forming force and microstructural development. The workability was determined by considering the forming force, as a function of the forming temperature and the forming speed. The resulting microstructures have been characterized by means of metallographic sections. In addition, hardness measurements were carried out on the sections. The results of the forming tests show that the flow stress of the tested steels decreases continuously in the temperature range of 500 to 800°C. A forming in the two-phase region leads to a mixed microstructure but the formability of the investigated materials increases further.
Translated title of the contributionCharacterization of the microstructural development and formability in warm forming of steels
Original languageGerman
QualificationDipl.-Ing.
Supervisors/Advisors
  • Buchmayr, Bruno, Supervisor (internal)
Award date7 Apr 2017
Publication statusPublished - 2017

Bibliographical note

embargoed until null

Keywords

  • characterization
  • Characterization
  • warm
  • forming
  • formability
  • microstructural
  • steel
  • steels

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