Moscow Polytechnic University, Moscow, Russia:

E. A. Galaktionova, Master’s Student, Dept. of Materials Forming and Additive Technologies, e-mail: ekgalaktionova1@mail.ru
Le Chung Zung, Postgraduate Student, Dept. of Materials Forming and Additive Technologies, e-mail: sea.lawyer.vn@gmail.com
Yu. K. Filippov, Dr. Eng., Prof., Dept. of Materials Forming and Additive Technologies, e-mail: yulianf@mail.ru
D. A. Gnevashev, Cand. Eng., Associate Prof., Acting Head of Dept. of Materials Forming and Additive Technologies, e-mail: dengnevashev@mail.ru

The dependence between the hardness of the deformed metal and the stress intensity during plastic deformation has been investigated and established. A calibration graph of the dependence of hardness on the amount of deformation for steel 20 GOST 1050-2013 has been built, thereby obtaining the possibility of predicting the properties of parts obtained by cold forging. Production is currently carried out by outdated methods, using labor-intensive technology on metal-cutting equipment with preforming and with a large scrap metal. The part "hub" for the car clutch disc is made from two blanks (boss and flange) by permanent joining, which is obtained by cold forging with subsequent machining. To determine the dependence of hardness on the deformation intensity and stress intensity and to construct a calibration graph, experiments were carried out on the compression of samples from the researched metal. Due to good lubrication at the ends of the sample (periodically replaced polyethylene gaskets in combination with machine oil), the stress state can be considered linear. Stress state index K = 0.33. Lode-Nadai index μσ = 1. Also, to reduce the barrel-shaped according to height of the samples, the ratio of the initial sizes is within the following limits 2 ≥ h0 / d0 ≥ 1. Steel 20 was chosen for the research. Hot-rolled round steel bar according to was used as blanks. In the value of the accumulated deformation from e = 0.4 to 0.5, steel 20 corresponds to the hardness of steel 35 in the initial state, this makes it possible to reasonably replace the metal for forming parts.

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