Actual Problems in Machine Building 2015 No. 2

Actual Problems in Machine Building. 2015. N 2 Innovative Technologies in Mechanical Engineering ____________________________________________________________________ 142 8. Adetunji O.R., Kuye S.I., Alao M.J., Eng B.M. Microstructures of mild steel spring after heat treatment // The pacific journal of science and technology / http://www.akamaluniversity.us/PJST.htm , 2/2013, p. 11-13 CONTROL STRUCTURE ON THE СAST OF RAILWAYS Chertovskih E.O. 1 , Ph.D. student, e-mail: chertovskih13@gmail.com Gabets A.V. 2 , Ph.D. (Engineering), Development director, Gerter M.V. 3 , Engineer, e-mail: gerter-maksim@rambler.ru 1 I.I. Polzunov Altai State Technical University, 46 Lenina avenue, Barnaul, Altai region, 656038, Russian Federation 2 Altai Steel Casting Factory, 116/52 Kalinina st., Barnaul, 656037, Russian Federation 3 Test Center of Technical Equipment, 16 “22 Partszda” st., Novoaltaisk, 658087, Russian Federation Abstract The paper describes an approach to controlled cooling of steel 20GFL, which further ensures the formation of the expected structural components in the form of ferrite, pearlite, and lower and upper bainite on heat treatment of large railway castings. Control of intermediate transformation of austenite was carried out by recording the temperature and time of the front critical points Ar3, Ar1where increasing the speed of intermediate transformation made it possible to form globular coagulations of lower bainite. The use of controlled cooling showed decreased sensitivity to mild steel casting defects in the form of liquation and segregation by forming a favorable structure of lower bainite. An example of calculating the degree of deformation of t structure-forming elements after impact tests is given. Keywords austenite, pearlite, ferrite, upper bainite, lower bainite, mezoferrit, toughness, mild steel