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In this work, we propose a unified description of the softening behavior of a β metastable alloy and Ti6Al4V alloy. In the first part we provide sound evidence that the hot deformation of Ti6Al4V of the beta phase above and below the beta transus temperature takes place solely by dynamic recovery at moderate strains, similarly to the behavior of the Ti5Al5Mo5V3Cr1Zr near-beta alloy. This study was possible due to the combination of the fast cooling rates achieved after controlled hot deformation and the reconstruction of the parent beta phase from electron backscattered diffraction measurements of the frozen alpha phase by using an innovative developed algorithm. The dynamic recovery as a common dynamic restoration behavior for Ti6Al4V and Ti5Al5Mo5V3Cr1Zr is described mathematically with a Derby type relationship of the subgrain size and the stress of the beta phase. A rule of mixture allows the determination of the load partition between the two allotropic phases.

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Medium-Mn steels are one of the promising candidates to achieve the desired mechanical properties in the 3rd generation of cold rolled advanced high strength steels (AHSS) for automotive applications. Their duplex microstructure consists of a ferritic matrix with a substantial amount of metastable retained austenite, which transforms to strain-induced martensite upon forming. This strengthening mechanism, well known as the TRansformation Induced Plasticity (TRIP) effect, provides the steel an excellent combination of high strength and elongation with a product of RmxA80 up to 30.000 MPa%. As hot rolling is one of the crucial steps during their production, the hot deformation behavior of Medium-Mn steels has to be thoroughly evaluated during their development stage.Therefore, the present contribution studied the hot deformation response of a 0.1 %C 5.5 %Mn steel by means of hot compression tests using a Gleeble® 3800 device. The influence of different deformation temperatures (900-1100 °C) and strain rates (0.1-10 s-1) on the stress-strain behavior was investigated. The flow curves were analyzed and corrected by the effects of adiabatic heating.Furthermore, the strain rate sensitivity m of the material was determined by evaluating stress values at different strain rates for given temperatures and strains. The m-values can be used to predict the deformation behavior of the material within the investigated range of parameters.Lastly, the hot working behavior of an alternative steel concept for a 3rd Generation AHSS with significantly lower Mn-content was comparatively investigated.

The creation of the heterogeneous joints at materials with the different physical and mechanical properties is always problematic. As one of methods by which can be achieved very good results is there a diffusion welding. The aim of paper is to show the possibilities of diffusion welding utilization at creation the heterogeneous joints between Titan grade 2 and high-alloyed austenitic steel AISI 316L. The fundamental theory of diffusion and also scheme and realization of experimentally created diffusion welds in the thermal-mechanical simulator Gleeble® 3500 is described in the article. Furthermore, procedure of technological parameters selection when optimization of heterogeneous joint strength properties including metallographic evaluation are taken into account, are also presented.

For understanding and describing the materials behaviour during phase transformations, dilatometer measurements are commonly used in the scientific community. Generally, standard CCT diagrams are generated by means of dilatometer experiments. However, in many cases, real weld cycles are more suitable for studying the materials behaviour instead of using CCT diagrams. In this regard we talk about so-called in-situ diagrams.In this work, two different devices have been used to obtain CCT as well as in-situ diagrams of a low alloyed steel 10GN2MFA. The goal was to compare the results obtained on the one hand by using a widely used standard dilatometer (Bähr DIL-805A/D) and on the other hand by the usage of a thermomechanical simulator called Gleeble®3800. The paper should finally show advantages as well as disadvantages of using different devices and to keep in mind that the optimal measurement method depends on different parameters. Realized experiments also have revealed the range of operational and diagnostic potential of used devices.

This study investigates the hot deformation behavior of a new Al-Mg-Sc-Zr alloy under plane strain conditions. Flow curves corrected for deformation heating were calculated for strain rates between 0.01 and 10s-1 in a temperature range of 200 to 400°C. To evaluate the deformation behavior, strain rate sensitivity as well as flow localization parameter maps were calculated for strains of 0.2, 0.4, and 0.6. In addition, microstructural investigations and hardness measurements were performed for selected samples. It was shown that the flow stress decreased with deacreasing strain rate and increasing temperature. The best formability was observed for high strain rates and low temperatures as well as for low strain rates and high temperatures. In these cases no flow instabilities were observed.