Effects of cold rolling on the microstructure and properties of Fe-Cr-Ni-Mo-Ti maraging steel

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2018-01, Vol.712, p.663-670
• Main Authors: Lian, Yong, Huang, Jinfeng, Zhang, Jin, Zhao, Chao, Gao, Wen, Zhang, Zunjun, Ma, Minyu
• Format: Article
• Language: English
• Subjects: Age hardening; Aging (metallurgy); Aging (natural); Chromium; Cold rolling; Cold-rolled steel; Deformation; Deformation effects; Dislocation density; Electron microscopy; Iron; Maraging steel; Maraging steels; Martensite; Martensitic transformations; Mechanical properties; Microhardness; Microstructure; Molybdenum; Nickel; Optical microscopy; Plastic deformation; Precipitates; Precipitation hardening steels; Strain hardening; Titanium; X-ray diffraction
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2017.12.041

The effects of cold deformation on the evolution of the microstructure and mechanical properties of Fe-Cr-Ni-Mo-Ti maraging steel were investigated. The microstructural changes during cold rolling were observed using optical microscopy (OM), electron back-scattered diffraction (EBSD), transmission electron microscopy (TEM) and X-ray diffraction (XRD), which were related to the mechanical properties as measured by micro-hardness and tensile testing. The remaining austenite in the as-quenched specimens was found to transform into martensite during cold deformation. High-density dislocations were produced in the martensite matrix by plastic deformation, which accelerate the aging response by promoting the formation of η-Ni3Ti precipitates. The strain hardening was partially conserved due to static recovery during the aging process. The cold rolled steel showed a very high hardening response, resulting in an increase in yield strength during the subsequently aging treatment at 510°C, with a detectable loss in ductility.