Positionsgenaue Herstellung einer Fügeverbindung aus Stahl- und Sphärogussvierkanthohlprofilen

Stange, Thomas

kassel university press, ISBN: 978-3-86219-502-2, 2013, 210 Pages
(Forschungsberichte aus dem Institut für Werkstofftechnik - Metallische Werkstoffe 13)

Zugl.: Kassel, Univ., Diss. 2012

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Content: The paper at hand focuses on the positionally accurate connection between two square profiles. The profiles are made of fine grained structural steel E460N and spheroidal cast iron GJS600-3. Contemporary welding techniques do not yet support this type of connection. The higher section modulus in comparison with a round connection, and the positionally accurate joining of finished processed components into a composite component facilitate cost-effective and weight-reduced manufacturing.

The approach chosen is to deoxidise both joining surfaces prior to joining. In a first step, the components are heated by induction, and are then joined by compression. The paper discusses the problems arising from inductive heating, deoxidation and compressing of the components. A process diagram illustrates which factors may influence component life expectancy under fatigue loading.

“Pre-process” outlines the influence of induction heating, the deoxidising agent and the components. There are also characteristic temperature distributions in the joining area; while it is possible to minimise undesired gradients it is not possible to totally eliminate them. “Core-process” describes the influence of the press and of the “pre-processed” components, and the typical weld seam that is characteristic for this welding process.

The internal stresses measured primarily result from the diverging coefficients of expansion of the materials used. The paper at hand includes assessments of the influence of internal stresses on the components’ life expectancy.

In addition, the strength of the joined connection is depicted for static load of the component and on finished samples, via tensile test.

The - factors influencing life - expectancy under fatigue loading are analysed. The expected risk of fatigue fracture is explored, with reference to temperature levels, internal stresses and notch effect. These expectations are compared with results of fatigue tests and are then discussed.

Complementing this discussion is a discourse on the heat / cold - sensitivity of the process with regard to fatigue life expectancy.

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