|Number of page(s)||6|
|Section||Principles, Simulations, Materials: Advanced Materials|
|Published online||01 September 2009|
Peculiarities of structure and thermomechanical strengthening of martensitic structural steels microalloyed by nitrogenV.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