Einfluss von Schmiede- und Abkühlbedingungen auf das Gefüge und die Eigenschaften ausgewählter AFP-Stähle

Translated title of the contribution: Influence of Forging and Cooling Parameters on the Microstructure and Properties of Selected Direct Air Cooled Medium Carbon Low Alloy Steels

Harald Lehofer

Research output: ThesisMaster's Thesis

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Abstract

Quenched and tempered steels are usually the first choice for drop forged parts that have to carry high loads. These steels require time, energy and cost intensive heat treatment. Direct air cooled steels are a possible alternative. They have a ferritic-pearlitic microstructure and get their strength from precipitation hardening. These steels do not require an additional heat treatment. It is no problem to reach the required strength level, but usually the toughness values are too low. In this work three steels with different carbon, microalloying and nitrogen content are compared. Forging tests with variation of forging temperature and cooling rate were done on an existing part. Additionally upsetting tests in laboratory scale with variation of forming temperature and different precipitation steps during cooling. The forging tests showed no influence of the cooling rate on the ferritic-pearlitic microstructure. A precipitation step leads to a slight promotion of ferrite for the steel with higher nitrogen content. Deformation temperature has a big influence on the microstructure. The steel with lower carbon content exhibited a more uniform ferrite distribution and higher toughness even at higher deformation temperatures.
Translated title of the contributionInfluence of Forging and Cooling Parameters on the Microstructure and Properties of Selected Direct Air Cooled Medium Carbon Low Alloy Steels
Original languageGerman
QualificationDipl.-Ing.
Supervisors/Advisors
  • Buchmayr, Bruno, Supervisor (internal)
Award date29 Jun 2007
Publication statusPublished - 2007

Bibliographical note

embargoed until null

Keywords

  • Direct air cooled medium carbon low alloy Drop forging Microalloying Precipitation Ferrite-pearlite Vanadium Niobium Nitrogen

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