M.I. Nagimov1, S.K. Mukhtarov1, F.Z. Utyashev1*, R.Y. Sukhorukov2§
1Institute for Metals Superplasticity Problems RAS, 39 Khalturin St., Ufa, 450001, Russia
2A. Blagonravov Institute of Machines Science RAS, 4 Maly Kharitonievskiy Pereulok, Moscow, 101990, Russia


It is well known that chromium steels are the material for the manufacture of critical parts. Usually parts made out of such materials deformed at room or hot temperature. This paper shows the development mode for deformation under isothermal condition at hot temperatures. The investigation results of chromium steel 11Kh11N2V2MF-Sh specimens after uniaxial tensile test at temperatures in the range 700-1100°C and at the strain rates 10-3-10-1 s-1 were presented. The mechanical properties of steel under uniaxial tension were determined. It is shown that the maximum ductility achieved within temperature range 800-1000°C and a strain rate of 10-3 s-1, and was about 115-103%. At other investigated temperatures and strain rates the elongation was about 77-99% and reduction of area 65-85%. The most longest-stable stage flow is observed at a strain rate of 10-2 s-1 and at temperatures 800-900°C, according to relationships between the true stress and the true strain in the tested temperature-strain rate conditions. The structure of the specimens after the tensile tests was investigated. It is shown that the decreasing temperature and strain rate leads to the formation of fine grains. Globular  grains with a mean size of 3 m were formed after tension of specimen at 800°C and a strain rate of 10-3 s-1 on elongation of about 115%. An average  grain size increased to 25 m after tension at a temperature of 1000°C.

Accepted: 26 May 2015

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