Transformation plasticity in boron-bearing low carbon steel

• Published in: Metals and materials international Vol. 21; no. 5; pp. 799 - 804
• Main Authors: Jeong, Hye-Jin, Kim, Moon-Jo, Kim, Dong-Wan, Suh, Dong-Woo, Oh, Jin-Keun, Han, Heung Nam
• Format: Journal Article
• Language: English
• Published: Seoul The Korean Institute of Metals and Materials 01.09.2015; Springer Nature B.V; 대한금속·재료학회
• Subjects: Austenite; Bearing steels; Boron; Characterization and Evaluation of Materials; Chemistry and Materials Science; Cooling; Diffusion; Diffusion rate; Engineering Thermodynamics; Ferrite; Heat and Mass Transfer; High strength steels; Low carbon steel; Low carbon steels; Machines; Magnetic Materials; Magnetism; Manufacturing; Materials Science; Metallic Materials; Phase transformations; Phase transitions; Plastic properties; Plasticity; Processes; Secondary ion mass spectroscopy; Segregations; Solid Mechanics; Solid phases; Spectrum analysis; Steels; Strain; Transformations; Yield stress; 재료공학; plasticity; diffusion; SIMS; segregation; phase transformation
• ISSN: 1598-9623; 2005-4149
• DOI: 10.1007/s12540-015-5215-y

The transformation plasticity (TP), which indicates that permanent strain remains after solid-solid phase transformation, even under much smaller stress than the yield stress, has been described by a vacancy diffusion mechanism in the migrating interface during diffusional phase transformation. In this study, the influence of boron (B) addition on the TP of low carbon high strength steel was investigated through the observation of the B segregation in the phase interface between primary austenite phase and ferrite phase using secondary ion mass spectroscopy. The B segregation at the austenite-ferrite phase interface was confirmed to cause drastic decrease of the TP strain by comparison of the dilatation behavior of B-bearing and B-free steels under a tensile force during slow cooling, where the diffusional phase transformation occurs in B-bearing steel. Furthermore, it was also confirmed that the velocity of B diffusion is larger than the migration velocity of interface at the given temperature through a calculation based on Fick’s law.