DOI: 10.18503/1995-2732-2026-24-3-43-53
Abstract
The use of light-alloy drill pipes is currently highly relevant. One of the problems in their production is the formation of longitudinal cracks during hot extrusion. The aim of this study is to establish the relationship between the stress-strain state and the formation of longitudinal cracks in light-alloy drill pipes with external end thickenings. Pipes made of D16T alloy have been selected as the object of study. Computer modeling has been used to determine the values of tangential tensile stresses and strain rate in the deformation zone and expansion zone on the conical section of the extrusion mandrel that lead to the formation of longitudinal cracks on the outer surface of the pipes in the zone of the end thickenings and in the transition zones from the thickened section to the main section. It has been found that the most critical zone in terms of crack formation is the outer surface of the front end of the pipe. In addition, it has been established that the swaged end thickening is characterized by a lower level of tangential tensile stresses than the outlet end thickening. The study has demonstrated that simultaneously reducing the billet and tooling temperatures by 20°C and the tooling speed by 0.4 mm/s results in a significant decrease in the level of tensile stresses in the critical zones of the pipe. Changing the temperature and speed conditions of the process under actual production conditions resulted in a 2.6-fold reduction in the percentage of nonconforming products due to the “longitudinal cracks” defect.
Keywords
aluminum alloy, light alloy drill pipes, longitudinal cracks, tangential stresses, strain rate, modeling
For citation
Zamaraeva Yu.V., Loginov Yu.N., Degtyareva O.F., Razinkin А.V. Influence of the Stress-Strain State During the Extrusion of a Light-Alloy Drill Pipe on Crack Formation. Vestnik Magnitogorskogo Gosudarstvennogo Tekhnicheskogo Universiteta im. G.I. Nosova [Vestnik of Nosov Magnitogorsk State Technical University]. 2026, vol. 24, no. 3, pp. 43-53. https://doi.org/10.18503/1995-2732-2026-24-3-43-53
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