Effect of an Overequilibrium Nitrogen Content on the Structure, Phase Composition, and Mechanical Properties of Low-Alloy Steel

Autor: L. G. Rigina, S. O. Muradyan, A.A. Makarov, M. V. Kostina, M.A. Druzhnov, A. E. Kudryashov, S. A. Krylov, Valentina Kostina
Rok vydání: 2021
Předmět:
Zdroj: Russian Metallurgy (Metally). 2021:1060-1074
ISSN: 1555-6255
0036-0295
DOI: 10.1134/s0036029521090081
Popis: The structure, phase composition, static strength, and impact toughness of 10Kh3A steel of two heats with a nitrogen content higher than the solubility limit under standard conditions (from here on, overequilibrium content of 0.105 and 0.173% N at [C] + [N] = 0.26 and 0.3%, respectively) are studied. The steel is produced by electroslag remelting under nitrogen pressure (ESRP). The effect of this method on the inclusion cleanliness of steel in comparison with the electrode metal (grade 10 steel) is investigated. The porosity of the steel ingot is estimated in the initial state, after forging, and after hot isostatic pressing (HIP). Hot plastic deformation by forging decreases the volume fraction of pores from 0.07% (in the as-cast metal) to 0.013%. Additional HIP weakly affects the volume fraction of pores and does not change the pore size. The effects of the hot-rolling temperature and reduction (800, 850, 900–1050°C and e = 10, 20–90%, respectively), the quenching temperature, and the rate of subsequent cooling on the steel structure are studied. The conditions that provide the formation of a fine-grained martensitic structure in the steel with 0.173% N and allow a high level of hardness and tensile strength to 1800 MPa at satisfactory ductility to be achieved are revealed. The steel with 0.173% N is shown to have a better combination of strength and ductility than the steel with 0.105% N.
Databáze: OpenAIRE
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