The properties of the well known enhanced steel 12 Cr Mo9-10 are compared with those of the most recent generation of modified CrMoV steels who are characterized by the addition of vanadium. The comparison concerns the base material properties before and after heat treatment, as well as the influence of hot forming and welding with and without step cooling. Creep data are also reported.

The three-dimensional atom-probe is the only analytical microscope able to map out the 3D distribution of chemical species at the atomic scale. Combined with a Field Ion Microscope, 3D Atom Probe is particularly well adapted to the investigation of the fine-scale features of the microstructure of metallic alloys. 3D atom probe makes it possible to measure quantitatively the composition in a small region that can be selected arbitrarily in the reconstructed volume. This way, the composition of small precipitates or that of the surrounding solid solution or even that of a thin layer close to interfaces can be measured. The potential of this new generation of analytical microscope is illustrated through examples (segregation of boron to planar faults in FeAl and superalloys, precipitation and ordering...).

The fire resistance of structures is one of the main brakes concerning the development of steel in buildings. This handicap of steel is in order to disappear due to the results of recent researches that permit to dimension the steel structures by considering the natural fire and the active fire fighting measures. In the frame of an ECSC financed research, an interactive calculation software has been developed with the aim of enabling engineering offices to perform easily calculations under natural fire conditions. This paper describes this new tool that should contribute to the promotion of steel by making the dimensioning under fire conditions easier and more competitive.

A natural kaolin material, which contains 45 wt % of alumina and less than 1 wt % of metal oxide impurities, has been submitted to thermal treatments in the temperature range 1 000-1 450 °C. The cristobalite development is studied by X-ray diffraction, using the broadening of line {101}. The apparent grain sizes of cristobalite, measured by the integral width of the line, change as a function of thermal treatment. Nevertheless, the apparent total content of the cristobalite remains constant. In the case of a chamotte material, which contains 42 wt % alumina and 3 to 4 wt % of metal oxide impurities, the apparent cristobalite grain sizes are of order of magnitude of the nanometer and the total apparent content is slightly lower. Finally, the thermal expansion coefficient, α (T), of the first material is higher, during the cristobalite transformation α → β, than that of the chamotte material.

Intersittial free (IF) steels used to produce cold rolled sheets are known to be hyper-drawable after recrystallization by continuous annealing. This is reflected by a low proof stress, a high work-hardening coefficient and a high r-value. From an industrial point of view, it is also important now to know how these properties change if annealing does not lead to complete recrystallization.