Actual Problems in Machine Building 2017 Vol. 4 No. 4

Актуальные проблемы в машиностроении . Том 4. № 4. 2017 Инновационные технологии в машиностроении ____________________________________________________________________ 15 INFLUENCE OF BORIDING ON DIMENSIONAL ACCURACY AND FRAGILITY OF SURFACE PRECISION PARTS MADE OF COLD WORK TOOL STEELS Konstantinov V.M. , D.Sc. (Engineering), Professor, e-mail: v_m_konst@mail.ru Dashkevich V.G. , Ph.D. (Engineering), Associate Professor, e-mail: vladimir_dvl@tut.by Kovalchuk A.V. , Post-graduate Student, e-mail: a-v-kov@yandex.com Belorussian National Technical University, ave. Nezavisimosty, 65, Minsk, 220013, the Republic of Belarus Abstract The estimation of factor of the fragility of the two-phase boride layers obtained on steels «У8А» and «9XC», depending on the saturation temperature and exposure time. The regression equations that allowed to define more efficient modes boriding process and provide a measure of phase boundary at the interface FeB / Fe 2 B at 120 ... 140 MPa. Refined data on changes in the geometric characteristics of the surface of the product resulting in a powder boriding environment. Constructed a nomogram for determining the gain of the linear dimensions of parts of cold work tool steels «У8А» and «9XC» the holding time at boriding in the temperature range 930 ... 950 ° C. To study the value of growth options boriding linear dimensions were as follows: steel «У8А» – 14 ... 25% of the thickness of the boride layer on the side, for steel «9XC» – 10 ... 21%. Keywords thermochemical treatment, boriding, diffusion layer, fragility, precision details, dimensional accuracy