Generation of a Layer of Severe Plastic Deformation near Friction Surfaces in Upsetting of Steel Specimens

Abstract

Narrow layers of severe plastic deformation are often generated near frictional interfaces in deformation processes as a result of shear deformation caused by friction. This results in material behavior that is very different from that encountered in conventional tests. To develop models capable of predicting the behavior of material near frictional surfaces, it is necessary to design and carry out tests that account for typical features of deformation processes in a narrow sub-surface layer. In the present paper, upsetting of steel specimens between conical and flat dies is used as such a test. The objective of the paper is to correlate the thickness of the layer of severe plastic deformation generated near the friction surface and the die angle using a new criterion for determining the boundary between the layer of severe plastic deformation and the bulk.

Effect of Frictional Conditions on the Generation of Fine Grain Layers in Drawing of Thin Steel Wires

“…A distinguished feature of the present research is that the effect of frictional conditions on the generation of fine grain layers is studied using the process of drawing of thin wires. Another distinguishing feature of this research, when compared to [14,15], is that the ratio of the thickness of the fine grain layer to the radius of wires is much larger than the ratio of the thickness of the layer to…”

“…One of these issues is that it is impossible to introduce a criterion that determines the thickness of the layer of intensive plastic deformation unambiguously. One possible criterion has been proposed in [15]. However, it is evident that the criterion should depend on the material.…”

“…Such a study was initiated in [14], where the process of extrusion through conical dies was used for revealing the dependence of the thickness of the fine grain layer on the die angle. For the same purpose, the process of upsetting with conical dies was adopted in [15]. In [14][15][16], the contact surface between the tool and test piece was intentionally treated to increase the friction stress as much as possible.…”

“…For the same purpose, the process of upsetting with conical dies was adopted in [15]. In [14][15][16], the contact surface between the tool and test piece was intentionally treated to increase the friction stress as much as possible. Thus, these papers all dealt with the effect of geometric parameters of the processes on fine grain layers.…”

Advances in Plastic Forming of Metals

“…Behrens et al [3] numerically examine the formation of an oxide scale during hot forging of steel and it effect on material flow and frictional conditions. Alexandrov et al [4] examine the formation of a severely-deformed layer near the surface due to friction-induced shearing. They propose a new criterion for determining the boundary between the layer of severe plastic deformation and the bulk of the material.…”