Comparative evaluation of austenite grain in high-strength rail steel during welding, thermal processing and plasma surface hardening

International Conference on Mechanical Engineering, Automation and Control Systems 2018

Kolosov, A.D.^1 ; Gozbenko, V.E.^2 ; Shtayger, M.G.^3 ; Kargapoltsev, S.K.^4 ; Balanovskiy, A.E.^1 ; Karlina, A.I.^1 ; Sivtsov, A.V.^5 ; Nebogin, S.A.^1

Irkutsk National Research Technical University, 83, Lermontov Street, Irkutsk

664074, Russia^1

Angarsk State Technical University, 60, Chaykovskogo Street, Angarsk

665835, Russia^2

MC Mechel Steel, 1, Krasnoarmeysky Street, Moscow

125167, Russia^3

Irkutsk State Transport University, 15, Chernyshevsky Street, Irkutsk

664074, Russia^4

Institute of Metallurgy Ural Branch, Russian Academy of Sciences, 101, Amudsena, Ekaterinburg

620016, Russia^5

关键词: Comparative evaluations;    Heating temperatures;    High temperature;    Individual grains;    Initial structures;    Minimum grain sizes;    Structural composition;    Thermal influence;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/560/1/012185/pdf
DOI  :  10.1088/1757-899X/560/1/012185

来源: IOP

【 摘 要 】

In the process of plasma surface hardening, a surface layer that consists of zones of different sizes with different phase and structural composition is formed. The minimum grain size for plasma surface heating is determined by the initial austenitic grain. Its size depends on the dispersion of the initial structure. The rate of plasma heating at 200-1000 °C/s affects the size of the initial grain. The further growth of austenite crystallites with an increase of temperature essentially depends on the heating rate: small rates and high temperatures of plasma surface heating can lead to a significant enlargement of the grain. Increase of the heating temperature in the zone of thermal influence during welding from 900 to 1040 °C of rail steel 76F leads to the growth of the austenitic grain from No. 9 to No. 7 and individual grains - from No. 8 to No. 3. The largest austenite grains while heated at 1000 and 1040 °C form separate zones where conglomerates of large grains predominate. Stiffness of 76F steel, heat-strengthened on the troosto-sorbitol structure, deteriorates substantially when the temperature of rapid heating increases from 900 to 1040 °C. This also increases the instability of stiffness.