Fabrication of Fe-Cr-Mo powder metallurgy steel via a mechanical-alloying process

• Published in: Metals and materials international Vol. 21; no. 6; pp. 1031 - 1037
• Main Authors: Park, Jooyoung, Jeong, Gowoon, Kang, Singon, Lee, Seok-Jae, Choi, Hyunjoo
• Format: Journal Article
• Language: English
• Published: Seoul The Korean Institute of Metals and Materials 01.11.2015; Springer Nature B.V; 대한금속·재료학회
• Subjects: Advanced materials; Alloy powders; Alloying; Atomizing; Bainite; Characterization and Evaluation of Materials; Chemistry and Materials Science; Chromium; Chromium base alloys; Engineering Thermodynamics; Ferrite; Ferrous alloys; Hardness; Heat and Mass Transfer; Iron; Iron alloys; Low alloy steels; Machines; Magnetic Materials; Magnetism; Manufacturing; Martensite; Materials Science; Mechanical properties; Metallic Materials; Metallurgical analysis; Molybdenum; Particle size; Phase shift; Phase transitions; Powder metallurgy; Processes; Scanning electron microscopy; Sintering (powder metallurgy); Solid Mechanics; Stainless steel; Steels; Water; Water hardness; 재료공학; alloys; hardness test; microstructure; powder processing; mechanical properties
• ISSN: 1598-9623; 2005-4149
• DOI: 10.1007/s12540-015-5189-9

In this study, we employed a mechanical–alloying process to manufacture low-alloy CrL and CrM steel powders that have similar specifications to their water-atomized counterparts. X-ray diffraction showed that Mo and Cr are alloyed in Fe after four cycles of planetary milling for 1 h at 150 RPM with 15-min pauses between the cycles (designated as P2C4 process). Furthermore, the measured powder size was found to be similar to that of the water-atomized counterparts according to both scanning electron microscope images and laser particle size analysis. The samples were sintered at 1120 °C, after which the P2C4-milled CrL showed similar hardness to that of water-atomized CrL, whereas the P2C4-milled CrM showed about 45% lower hardness than that of its water-atomized counterpart. Water-atomized CrM consists of a well-developed lathtype microstructure (bainite or martensite), while a higher fraction of polygonal ferrite is observed in P2C4-milled CrM. This phase difference causes the reduction of hardness in the P2C4-milled CrM, implying that the phase transformation behavior of specimens produced via powder metallurgy is influenced by the powder fabrication method.