Effect of hot isostatic pressing temperature on the properties of inert gas atomized maraging steel

Super rapid crystallization of melts for maraging steels has a considerable effect on the nature of their phase transformation, structures, and properties. Depending on solidification rate and subsequent cooling it is possible to form in steel 01N17K12M5T structures of the following types: 1) entirely martensitic; 2) entirely ferritic; 3) a mixture of martensitic and austenitic components. The maximum microhardness is achieved with formation in the test steel of a highly dispersed entirely martensitic structure. An increase in the microhardness of martensitic structure is governed mainly by the small width of martensitic platelets. Results of experimental data are in good agreement with the Hall-Petch relationship, which points to the decisive role of the interface in metal strengthening.

Effect of superrapid crystallization on the structure and properties of maraging steels

The strength of extruded and heat-treated bar of 18Ni 350 maraging steel produced from prealloyed powder has been found to be comparable to that of conventional, wrought 18Ni 350 maraging steel. Impact toughness was considerably higher. In contrast, properties of bar Obtained from an elemental powder mix were markedly inferior to wrought 18Ni 350 maraging steel. The high toughness of Charpy V-notch specimens produced from prealloyed powder was partly attributed to the presence of continuous, aluminium-rich stringers.This resulted in delamination of the specimens during testing and led to a fibrous fracture. Charpy V-notch specimens produced from the elemental powders also contained stringers. However, these were not continuous and therefore did not cause delamination. The resulting fracture surface was flat and relatively featureless. Electron-microprobe analysis has shown that the morphology of the stringers is largely determined by their composition and the composition at the stringer/matrix int...

E. Snape

Papers

THE PROPERTIES OF 18Ni 350 MARAGING STEEL PRODUCED FROM ELEMENTAL AND PREALLOYED POWDERS