TY - JOUR

T1 - The Influence of the Thermomechanical Processing Regime on the Structural Evolution of Mo-Nb-Ti-V Microalloyed Steel Subjected to High-Pressure Torsion

AU - Astafurova, Elena

AU - Maier, Galina

AU - Melnikov, Eugene

AU - Naydenkin, Eugene

AU - Smirnov, Aleksander

AU - Bataev, Vladimir

AU - Odessky, Pavel

AU - Dobatkin, Sergey

AU - Maier, Hans J.

N1 - Funding information: This study was supported by the Program of Fundamental Researches of the State Academies of Sciences for 2013 to 2020. The studies were conducted using the equipment of Belgorod State National Research University, Novosibirsk State Technical University, Institute of Strength Physics and Materials Science (NANOTECH center).

PY - 2017/4/6

Y1 - 2017/4/6

N2 - In the present study the effect of the thermal-mechanical processing regime—cold high-pressure torsion (HPT) at room temperature, cold HPT followed by annealing at 773 K (500 °C), and warm HPT at 723 K (450 °C)—on the peculiarities of the microstructure and microhardness of a Mo-Nb-Ti-V-0.08C microalloyed steel was analyzed. HPT processing resulted in high deformation and refinement of the initial structure and produced an ultrafine-grained microstructure featuring different morphologies with fine (<5 nm) and coarse (15 to 20 nm) carbides and with a mean size of the ferrite grain-subgrain structural elements of ≈100 nm. After room-temperature HPT, a mixed grain-subgrain structure with a high microhardness of 608 HV was obtained. Warm HPT caused formation of an ultrafine-grained structure with a microhardness of 553 HV. After annealing of cold HPT-processed specimens at 773 K (500 °C), a partial recovery of the structure occurred, but the average size of the structural elements and their distribution varied only slightly whereas the microhardness increased to 642 HV. The variations in the microhardness with the processing regime were correlated to changes in microstructural parameters (grain size, dislocation density and precipitation strengthening).

AB - In the present study the effect of the thermal-mechanical processing regime—cold high-pressure torsion (HPT) at room temperature, cold HPT followed by annealing at 773 K (500 °C), and warm HPT at 723 K (450 °C)—on the peculiarities of the microstructure and microhardness of a Mo-Nb-Ti-V-0.08C microalloyed steel was analyzed. HPT processing resulted in high deformation and refinement of the initial structure and produced an ultrafine-grained microstructure featuring different morphologies with fine (<5 nm) and coarse (15 to 20 nm) carbides and with a mean size of the ferrite grain-subgrain structural elements of ≈100 nm. After room-temperature HPT, a mixed grain-subgrain structure with a high microhardness of 608 HV was obtained. Warm HPT caused formation of an ultrafine-grained structure with a microhardness of 553 HV. After annealing of cold HPT-processed specimens at 773 K (500 °C), a partial recovery of the structure occurred, but the average size of the structural elements and their distribution varied only slightly whereas the microhardness increased to 642 HV. The variations in the microhardness with the processing regime were correlated to changes in microstructural parameters (grain size, dislocation density and precipitation strengthening).

UR - http://www.scopus.com/inward/record.url?scp=85017130086&partnerID=8YFLogxK

U2 - 10.1007/s11661-017-4085-y

DO - 10.1007/s11661-017-4085-y

M3 - Article

AN - SCOPUS:85017130086

VL - 48

SP - 3400

EP - 3409

JO - Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science

JF - Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science

SN - 1073-5623

IS - 7

ER -