Neutron diffraction study of a nitrogen martensitic steel 0Kh16N4AB under load

An austenitic-martensitic nitrogen steel 0Kh16N4AB has been studied under load using high-resolution neutron diffraction analysis on an FSD neutron diffractometer at an IBR-2 reactor (Dubna) and on a diffractometer with a focusing monochromator on a reactor of the Nuclear Physics Institute (Czech Republic). Young’s moduli calculated from different reflections of the martensite and austenite phases have been obtained. It has been found that the yield strength σ 0.2 corresponding to the slip plane (111) of the austenite phase is anomalously low and that with increasing degree of uniaxial tension the width of lines (111) γ strongly grows. In the steel under consideration the plane (111) of the austenite phase appears to be an easy-slip plane that ensures the enhanced properties of the steel, i.e., the combination of a high ultimate strength (1600 MPa) with a high plasticity (δ = 16%).