Details

Autor(en) / Beteiligte

• Polevoi, E. V.
• Simonov, Yu. N.
• Kozyrev, N. A.
• Shevchenko, R. A.
• Bashchenko, L. P.

Titel

Phase and Structural Transformations upon the Formation of a Welded Joint from Rail Steel. Report 1. Thermokinetic Diagram of Decomposition of Supercooled Austenite of R350LHT Rail Steel

Ist Teil von

• Steel in translation, 2022, Vol.52 (1), p.64-70

Ort / Verlag

Moscow: Pleiades Publishing

Erscheinungsjahr

2022

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• In this paper, we present a thermokinetic diagram of the decomposition of supercooled austenite of steel R350LHT built based on the results of dilatometric, metallographic, and durometric studies of the decomposition of supercooled austenite of steel R350LHT upon continuous cooling and under isothermal conditions. In the study of the decomposition of supercooled austenite during continuous cooling, cooling at a rate of 0.1 and 1°C/s was found to cause the decomposition of austenite in steel R350LHT according to the pearlite mechanism. After cooling at a lower rate, the pearlite structure is coarser and has a lower (289 HV) hardness. This is due to a higher temperature range of transformation, in which diffusion processes associated with the transformation of austenite into pearlite occur more actively. In the rate range from 5 to 10°C/s, the austenite decomposition undergoes according to the pearlite and martensite mechanism, which leads to the formation of a pearlite-martensite structure. When the austenite of the studied steel is cooled at a rate of 30 and 100°C/s, the transformation occurs according to the martensitic mechanism, and a martensitic structure with high hardness is formed. At an increase in the cooling rate of steel R350LHT, an increase in hardness from 289 (at 0.1°C/s) to 864–896 HV (at 100 and 30°C/s, respectively) is observed. The performed studies allow narrowing the boundaries of the search for the optimal parameters of the welding and heat treatment modes of the studied rail steel. To obtain the required structures and physical and mechanical properties (the austenite of R350LHT steel undergoes decomposition according to the pearlite mechanism), cooling should be carried out at a rate of no more than 1°C/s.