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Various physical methods for the determination of phase transformation temperatures were compared using C-Mn and C-Mn-V-Nb steels.The measurement using temperature scanner, variously located thermocouples, dilatometer, different thermal analysis (DTA) and anisothermal plastometric test were completed. The specimens were heated to 1 323 Kand 1 473 Kin the case of the C-Mn-V-Nb microalloyed steel. The aim of the different heat treatment were to obtain different levels of precipitates'dissolution. It was found that the better particles'distribution and precipitation due to the cooling lead to the enlargement of the two-phase region in the material. The good agreement of result gained by used methods was achieved. We found that all used methods can be used for common steels, but the temperature scanner seems not to be precious enough for microalloyed steels. [ABSTRACT FROM AUTHOR]

Energy dissipation and areas of process instability were investigated in two alloys. The first one was brass, the second one was the steel 9 Cr (P91). The tests were performed on torsion plastometer Setaram and on compression plastometer Gleeble. In the case of the steel 9 Cr identical heat was tested on both plastometers. The resulting 2D or 3D process maps indicate suitable areas of forming temperatures, magnitudes of deformation and strain rates. [ABSTRACT FROM AUTHOR]

This paper presents a new model for calculation of critical strain for initialization of dynamic recrystallization. The new model reflects the history of forming in the deformation zone during rolling. In this region of restricted deformation, the strain rate curve for the surface of the strip exhibits two peaks. These are the two reasons why the onset of dynamic recrystallization DRX near the surface of the rolled part occurs later than in theory during strip rolling. The present model had been used in a program for simulation of forming processes with the aid of FEM and a comparison between the physical experiment and a mathematical model had been drawn. [ABSTRACT FROM AUTHOR]

The application of finite element simulation to the problem of roll pass design for round bar rolling is considered. Two roll pass sequences were developed by analytical methods and then optimized using 2.5D Finite Element Method (FEM). The first one is a classical oval-round roll pass design. The second one is a combination of flat rolls and round roll passes. Relying on the simulation data obtained by FEM, the roll gaps were adjusted to achieve the required bar shape and the uniform distribution of rolling force between the passes. Advantages and disadvantages of each roll pass design were considered. [ABSTRACT FROM AUTHOR]