Distortion of components due to segregations of a low alloy SAE 5120 steel after blank and case hardening∗

M. Hunkel; F. Hoffmann; H.-W. Zoch

doi:10.3139/105.100421

Article

Distortion of components due to segregations of a low alloy SAE 5120 steel after blank and case hardening∗

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Published/Copyright: May 11, 2013

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From the journal HTM Journal of Heat Treatment and Materials Volume 62 Issue 4

Abstract

A conventional low alloy steel (SAE 5120, EN 20MnCr5) was investigated to determine length change and curvature during heat treatment due to segregations. Long cylindrical shafts were used to minimize the influence of the geometry. The shafts were taken eccentrically from semifinished bars with two different degrees of deformation. Two sets of multiple heat treatments were done for each deforming degree. One of them started with two slow cooling cycles and had a final blank hardening cycle. The other set was a slow cooling cycle and afterwards a case hardening cycle. Coordinate measurements were done before and after each heat treatment cycle. Significant differences in the length change as well as in the magnitude and direction of the curvature could be detected.

Kurzfassung

Wellen aus einem kommerziellen niedriglegierten Stahl (20MnCr5) wurden hinsichtlich der Längenänderungs- und Krümmungsverhalten während der Wärmebehandlung untersucht. Um den Einfluss der Geometrie zu minimieren, wurden lange zylindrische Wellen verwendet. Die Wellen wurden exzentrisch aus Halbzeug mit zwei verschiedenen Umformgraden entnommen. Zwei Wärmebehandlungszyklen wurden für jeden der beiden Umformgrade angewendet. Ein Wärmebehandlungszyklus beinhaltete zwei langsame Abkühlungen und eine abschließende Blindhärtung. Bei dem anderen Zyklus wurde eine Einsatzhärtung nach einer langsamen Abkühlung durchgeführt. Koordinatenmessungen wurden vor und nach jeder Wärmebehandlung durchgeführt, um den Verzug aufgrund der einzelnen Wärmebehandlungen zu bestimmen. Wesentliche Kenngröße waren die Längenänderung und die Richtung sowie der Betrag der Krümmung der Wellen.

∗

Lecture held by M. Hunkel at the 5^th Int. Conf. on Quenching and Control of Distortion and the European Conf. on Heat Treatment, 25–27 April 2007, in Berlin

Dr.-Ing. Martin Hunkel, born in 1966, studied Physics at the University of Karlsruhe and was awarded a PhD at the Freiburg University of Mining and Technology in 1998. Since 1998 he is a research assistant in the main department Materials Science of the Foundation Institute for Materials Science.

Prof. Dr.-Ing. habil. Franz Hoffmann, born in 1950, studied Mechanical Engineering at the University Karlsruhe. Since 1975 he operates at the Foundation Institute for Material Science in Bremen and there he is the Head of the Heat Treatment Department.

Prof. Dr. Ing. Hans-Werner Zoch, born in 1953, studied Mechanical and Process Engineering at the Technical University in Darmstadt and received his PhD at the faculty of Production Engineering at the University in Bremen. From 1980 till 2003 he worked for FAG Kugelfischer Georg Schäfer AG in Schweinfurt and later as Managing Director at Neue Materialien Bayreuth GmbH. Since 2004 he is Professor for Materials Science/Metals at the faculty of Production Engineering at the University in Bremen, Managing Director of the Foundation Institute for Materials Science and Coordinator of the Collaborative Research Center (SFB 570) “Distortion Engineering”.

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Published Online: 2013-05-11

Published in Print: 2007-08-01

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https://doi.org/10.3139/105.100421