National University of Science and Technology (NITU) „MISiS“ (Moscow, Russia):

P. Galkin, glk-omd@yandex.ru

B. A. Romantsev

GMT Gesellschaft fur metallurgische Technologie- und Softwareentwicklung mbH (Berlin, Germany):

A. Borowikow

Integration of the process of radial-displacement rolling stage into the Thermomechanical Treatment (TMT) allows to provide a flexible and economic production of a broad dimensional range of steel bars with high geometric tolerance and an optimum use of the potentials of material properties. The high degrees of deformation achieved per pass during the radial-displacement rolling stage results in a fine grain (subgrain) structure with improved mechanical properties. In the HDQT process, different combinations of temperature guiding and reductions values can be realized to obtain the specific crystalline structure. The paper introduces the new system design for thermomechanical treatment and, furthermore, highlights the first results of the tests performed on heat treated steel. First tests on spring steel 54SiCr6 using the HDQT process resulted the heightening of tensile strength in the range of appr. 10-15 % while maintaining the same strength characteristics compared to conventional processes. Diameter tolerances and ovalities of < 0.5 % over the entire length of the steel bar are possible with the HDCR stand. Compared to conventionally tempered material, remarkable increases in strength are possible while maintaining the same toughness.

1. Galkin S. P. Traektoriya techeniya deformirovannogo metalla na osnove kontrolyz protsessov radialno-sdvigovoy i vintovoy prokatki (Trajectory of deformed metal movement as the basis of the radial-displacement and screw rolling process control). Stal - Steel. 2004. No.7. p.70-72.

2. Borowikow A., Blei H. Integration of Screw Rolling in the Thermo-Mechanical Treatment of Steel Bars. The Roll Pass Designer. 2011. June. No. 72. p. 53-60.