Quenching and Deformation Dilatometer

• Subject Area: Materials Engineering
• Term: from 2022 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 514897779

The quenching and deformation dilatometer can be used in different operating modes. In the quenching mode, rapid inductive heating of metallic samples with heating rates of up to several 1000 K/s to temperatures of up to approx. 1500 °C and subsequent rapid quenching by means of a gas nozzle array with cooling rates of up to several 1000 K/s is possible. In parallel, the length change of the sample is measured. This allows the phase transformations during almost any heat treatment of metallic materials (which are associated with a sufficient volume change) to be monitored in-situ. In the deformation mode (compression or tension), these almost arbitrary heat treatments can be stopped at any time in order to characterise the material state present at the current temperature by its flow curve, even far from equilibrium (thermomechanical analysis). Metallic samples treated thermomechanically in this way can then be investigated with regard to their nanoscale material structure and serve as initial states for further thermal analyses by means of calorimetry.A new method integrated into dilatometry for the in-situ analysis of material structures is laser ultrasonic testing. Here, a sample surface is bombarded with a short laser pulse, which triggers an ultrasound wave inside the sample. The impact of this ultrasonic wave on the opposite sample surface is detected. Characteristics of the ultrasonic wave, such as the speed of sound and the attenuation, can be correlated with characteristics of the material structure. With this equipment, the proposed device has a unique selling point, which opens up completely new possibilities for the applicant to analyse phase transformations in-situ, which are associated with very small volume changes.The quenching and deformation dilatometer is thus an indispensable research device for the Chair of Materials Science at the University of Rostock with its research focus on metallic materials, heat treatment processes/equipment, heat treatment simulations and material data/material models for simulations. Heat treatment processes also include manufacturing processes that are intrinsically combined with heat treatment (e.g. casting, additive manufacturing, hot forming, joining). Current research projects in which the research equipment is to be used include precipitation hardening of Al alloys, twin-roll-casting of Al alloys, induction hardening of steels, inductive heat treatment of Ni-Ti alloys and additive manufacturing of Cu alloys. Planned research projects include additive manufacturing of Al alloys, case hardening of additively manufactured steels, superimposed artificial ageing and creep of Al alloys and sintering of high entropy alloys.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: Abschreck- und Umformdilatometer
• Instrumentation Group: 8650 Spezielle Kalorimeter
• Applicant Institution: Universität Rostock
• Leader: Professor Dr.-Ing. Olaf Keßler