Optimisation of Mechanical Properties of 18%Ni350 Grade Maraging Steel Using Novel Heat Treatment

J. Marcisz, M. Adamczyk, B. Garbarz
2017 Archives of Metallurgy and Materials  
The paper presents results of examinations of properties and microstructure of maraging steel grade MS350 (18Ni350) produced by a novel heat treatment method called "short-time ageing". It has been found that maraging steel after application of the short-time ageing achieves unique properties, in particular good combination of strength and impact toughness. After short-time ageing for time of heating up to 600 seconds at temperature of 550°C hardness in the range from 48 to 56 HRC, tensile
more » ... gth ranging from 2000 to 2250 MPa, yield strength from 1930 to 2170 MPa and total elongation in the range 7-8% as well as notch impact toughness of 20 J/cm2 at temperature minus 40°C were obtained. Results of microstructure examination in transmission electron microscope (TEM) with application of high resolution technique (HRTEM) have shown presence of Ni3Mo nano-precipitates of orthorhombic crystallographic structure. Precipitates were characterized by rod-like shape and were homogenously distributed in martensitic matrix of steel with high density of dislocations. The average size of cross-section of precipitates was ca. 4 nm while length reached several dozen of nm.
doi:10.1515/amm-2017-0010 fatcat:gzefj3qqwbda7kahzxivpamzby