Mathematical description of deformation resistance of IF steel including influence of phase transformations
Ivo Schindler1, Jiří Plura2, Vladimír Jurko3, Stanislav Rusz1, Pavel Suchánek1, Marcel Janošec1
1VSB – Technical University of Ostrava, Institute of Modelling and Control of Forming Processes, 17. listopadu 15, 708 33 Ostrava, Czech Republic. 2VSB – Technical University of Ostrava, Department of Quality Control and Assurance, 17. listopadu 15, 708 33 Ostrava, Czech Republic. 3U. S. Steel Kosice, s.r.o., Vstupny areal U. S. Steel, 044 54 Kosice, Slovak Republic.
DOI:
https://doi.org/10.7494/cmms.2007.1.0115
Abstract:
The aim of work was to describe by a single equation deformation resistance of IF steel with titanium in the temperature range of 700 to 1200°C, in relation to the forming temperature T, logarithmic height strain eh and mean equivalent strain rate ė. The mean equivalent stress σm [MPa] was determined by an original procedure, based on laboratory rolling of flat samples with graded in thickness in the computer controlled mill Tandem. Values of σm were computed from values of the registered roll forces by means of a specially developed methodology that uses knowledge of a particular equation for description of the forming factor of the mill Tandem. Due to an intended application of results in rolling at very low temperatures (in the ferrite region), the samples were heated directly to the forming temperature, which influenced the temperature boundaries between the ferrite region, a two-phase region ferrite + austenite and the austenite region. Coefficients A, B, C and D were calculated in a simple equation of type σm = A eh B ė C exp(-D·T) for each of the given temperature ranges. A top phase of the work was represented by an attempt to describe the deformation behaviour by a single equation. After a large analysis a certain way was proposed in the end, which uses a cumulative function in which particular members are multiplied by coefficient 1 or 0, in dependence on a specific temperature. Calculations of specific coefficients had to be proposed in such a way so that they could react to surpassing of temperature boundaries between individual phase regions. Relative deviations of values σm, calculated on the basis of the gained universal equation back for conditions of the laboratory rolling, from values of the mean equivalent stress expressed directly from roll forces do not surpass ±10 % which may be considered to be good accuracy.
Cite as:
Schindler, I., Plura, J., & Jurko, V. Rusz, S., Suchánek, P., Janošec, M., (2007). Mathematical description of deformation resistance of if steel including influence of phase transformations. Computer Methods in Materials Science, 7(1), 24 – 28. https://doi.org/10.7494/cmms.2007.1.0115
Article (PDF):
Keywords:
IF steel, Laboratory rolling, Phase transformation, Statistic software, Model of deformation resistance
References: