Size effect in transient thermal fatigue testing and thermo-mechanical screening of coatings. (17th June 2008)

• Record Type: Journal Article
• Authors: Dour, G.; Medjedoub, F.; Diaconu, G.; Girardin, D.; Michrafy, A.; Loulou, T.M.; Rezai-Aria, F.
• Is Part Of: International journal of microstructure and materials properties. Volume 3:Number 2/3(2008)
• Page Start: 311
• Page End: 325
• Publication Date: 2008-06-17
• Subjects: hot forming processes -- shaping processes -- hot work tool steels -- thermal fatigue -- thermo-mechanical loadings -- thermal stresses -- heat checking -- coatings; Microstructure -- Periodicals; Materials -- Properties -- Periodicals; 620.11299
• Languages: English
• ISSNs: 1741-8410

Abstract

In an attempt to bring new ideas to thermal fatigue analysis of tools, we propose the principle of the two driving forces leading to damage by Thermal Fatigue (TF). After a definition of the two driving forces based on temperature and thermo-mechanical loadings, a procedure for evaluating them for in-service tools is proposed. In order to compare thermo-mechanical loadings in industrial tools to laboratory specimen, a normalisation of the thermo-mechanical equations is proposed. A size effect in those thermal mechanical problems is justified and used to set an original rule to design transient TF tests. In a second example related to coating tools or bi-materials tools, the concept of thermo-mechanical screening is explained: it corresponds to the optimum combination of materials properties leading to the vanishment of thermal stresses at the mating surface of a tool. An example is given that shows some conditions in which this can happen, depending on the combination of material properties. An example of application is then proposed.