Evaluating deformation resistance during hot extrusion of tubes from nickel-based alloys
DOI:
https://doi.org/10.37142/2076-2151/2019-2(49)150Keywords:
tube-extrusion plants; deformation resistance; alloying elements; temperature; extrusion force; power.Abstract
Medvedev M., Andreiev V., Frolov Ia., Bobukh O. Evaluating deformation resistance during hot extrusion of tubes from nickel-based alloys // Material working by pressure. – 2019. – № 2 (49). - P. 150-155.
In theory and technology of metal forming, it is known that the value of deformation resistance is determining when calculating the power characteristics of the deformation process, for example, when extrusion tubes, as well as heating the metal in the deformation zone.
However, the use of theoretical relationships which are intended to determine the power conditions of the deformation process is very difficult due to difficulties in determining σист, empirical formulas are only suitable for those extrusion conditions under which they are obtained. In this connection, in determining the extrusion force on the tube-extrusion plants it`s customary to use of the generalized formula which includes the coefficient of proportionality that considers the deformation resistance, the geometry of the deformation zone and other extrusion conditions. Its value to the same extent depends on the chemical composition of the steel, temperature, degree and rate of deformation, as the true yield strength of the metal.
In the work, a method for assessing the value of deformation resistance during hot extrusion of tubes from nickel-based alloys, on tube-extrusion plants of various capacities, is developed. Under the basic conditions for various tube-extrusion plants, which are accepted as the most commonly used for extrusion nickel-based alloys: temperature of heating, wall thickness of the sleeves, the diameter of the sleeve of the container, as well as the time of transport operations. In this case, the drawing coefficient for these conditions was 8, the degree of deformation was 87.5 %, and the strain rate was 90 s-1.
Using the developed method, the force parameters of the hot extrusion of tubes from nickel-based alloys can be calculated, which allows us to determine the possibility of extrusion them on existing and designed tube-extrusion equipment both by steel and alloy grades, and by tubes sizes.
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