D. Baldissin

Microstructures in laser welded high strength steels

In this work, the effect of laser welding on the microstructure was studied for three Advanced High Strength Steels: transformation induced plasticity steel (TRIP), dual phase steel (DP) and martensitic steel. Two sheets of the same steel were laser welded and a microstructural study was performed by optical microscopy, scanning electron microscopy and X-ray diffraction. For all samples the welded zone was constituted by martensite and the heat affected zone shows a continuous change in microstructure depending on temperatures reached and on the different cooling rates. The change in mechanical properties in the welded area was followed by Vickers micro-hardness measurements. Quasi binary phase diagrams were calculated and, according to position of T0 lines, it was deduced that austenite is the primary phase forming during rapid solidification for all steels.

Thermodynamic Properties of CMSX-4 Superalloy: Results from the ThermoLab Project

This contribution reports the results of calorimetric measurements of the enthalpy of fusion and liquid specific heat carried out in different laboratories as part of the ground campaign of the Thermolab project. Different equipments and calibration methods have been used and critically evaluated. Thermodynamic calculations using the Thermocalc software have been performed and a comparison has been carried out with the experimental results.

Mechanical behaviour of metallic glasses related to thermal properties

The relationship between mechanical properties, the glass transition temperature and the heat content needed to reach it is discussed for various glass-formers to prove aspects of the mechanism of shear band propagation. Temperature profiles around shear bands are determined by means of finite element modelling. The results are used to interpret serrations and the effect of specimen size.