Concept of rotational compression between channel-dies
Experimental tests of rotational compression between channel-dies
FEM analysis of rotational compression between channel-dies
Results and discussion
In the test of rotational compression between channel-dies, cracking occurred in the axial zone of the specimen.
As the specimen was rotated, radial stresses along the axis of the specimen changed cyclically from compressive to tensile and back again, which, after the specimen had made a critical number of revolutions, led to the formation of a crack.
Despite the relatively long duration of the test under hot forming conditions, the temperature of the material in the axial zone of the specimen did not decrease, but, on the contrary, increased slightly as a result of the conversion of plastic work into heat.
To determine the critical value of damage at a given temperature using the rotational compression test, it was necessary to determine the critical forming length at which cracking occurred.
The critical value of material damage determined in the channel-die rotational compression test depended on the temperature of the test material, with an increase in temperature causing an increase in the critical value of damage.
Rotational compression in a channel is recommended to determine the critical values of material fatigue used in analyses of cross- and skew-rolling processes. In the case of hot rolling 50HS (1.5026) grade steel, the application of the equations shown in (4) is recommended.