Tensile Behavior of Ti,Mo-added Low Carbon Steels with Interphase Precipitation

• Published in: ISIJ International Vol. 54; no. 1; pp. 212 - 221
• Main Authors: Kamikawa, Naoya, Abe, Yoshihisa, Miyamoto, Goro, Funakawa, Yoshimasa, Furuhara, Tadashi
• Format: Journal Article
• Language: English
• Published: Tokyo The Iron and Steel Institute of Japan 2014; Iron and Steel Institute of Japan
• Subjects: Applied sciences; ductility; Exact sciences and technology; interphase precipitation; low carbon steel; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; precipitation strengthening; work hardening; Precipitation; Work hardening; Low carbon steel; Ductility; interphase precipitation; Mechanical properties; precipitation strengthening; Carbon steel; Tensile property; Precipitation hardening; Surface treatment; Strain hardening
• ISSN: 0915-1559; 1347-5460
• DOI: 10.2355/isijinternational.54.212

Tensile behavior and structure-property relationship of ferritic steels with nano-sized carbide dispersion were invesigated using Ti-added steel and Ti,Mo-added low carbon steels. By austenitizing followed by isothermal heat treatment at 700°C, polygonal ferrites containing very fine carbides of TiC and (Ti,Mo)C were obtained in the Ti-added and the Ti,Mo-added steels, respectively. The size of such carbides was finer in the Ti,Mo-added steel than in the Ti-added steel at the same isothermal holding. The results of tensile tests for these samples showed that the strength is higher as the carbide size is smaller. The structure-based strength calculation led to a good agreement with the experiments, when it was assumed that the Ashby-Orowan mechanism is dominant for precipitation strengthening of nano-sized alloy carbides. It was also suggested that a relatively large tensile ductility is related to enhanced recovery during the tensile deformation, accompanied with promotion of secondary slips or cross slips in a finer scale due to the nano-sized particles.