Open Access
Article Number 04010
Number of page(s) 6
Section Principles, Simulations, Materials: Advanced Materials
Published online 01 September 2009
ESOMAT 2009, 04010 (2009)
DOI: 10.1051/esomat/200904010

Peculiarities of structure and thermomechanical strengthening of martensitic structural steels microalloyed by nitrogen

V.G. Prokoshkina, L.M. Kaputkina and M.G. Medvedev

Moscow Institute of Steel and Alloys, Leninsky Prospect 4, 119049 Moscow, Russia

Published online: 1 September 2009

The effect of thermomechanical treatments on structure and properties of structural C(0.35-0.50)CrNiMoV steels microalloyed by nitrogen were studied using optical microscopy, X-ray diffraction analysis and mechanical testing. The hardness of martensite change as a function of austenitization temperature is presented for the steels with the same main composition but various summary C and N contents. Microalloying of structural steels by nitrogen results in complication of phase transformations and raising austenitization temperature for quenching and HTMT. A small quantity of undissolved carbonitrides promotes fine-grained structure preservation and heredity of the initial ascast structure. The heat and thermomechanical treatment regimes were determined which allowed the use of nitrogenmicroalloyed structural steels as high-strength ones. A complete dissolution of special carbonitrides during HTMT and following low-temperature tempering provide high strength level (by 300-500 MPa higher than for nitrogen-free analogs) combined with sufficient ductility and fracture toughness.

© Owned by the authors, published by EDP Sciences 2009