Formation mechanism and control methods of acicular ferrite in HSLA steels: A review

• Published in: Journal of materials science & technology Vol. 34; no. 5; pp. 737 - 744
• Main Authors: Shao, Yi, Liu, Chenxi, Yan, Zesheng, Li, Huijun, Liu, Yongchang
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.05.2018
• Subjects: Acicular ferrite; HSLA steels; Intercritical heat treatment; Mechanical properties; Microstructure; Step quenching; Thermo-mechanical controlled processing; Thermo-mechanical controlled processing; Intercritical heat treatment; Mechanical properties; Acicular ferrite; Step quenching; Microstructure; HSLA steels
• ISSN: 1005-0302; 1941-1162
• DOI: 10.1016/j.jmst.2017.11.020

High strength low alloy (HSLA) steels have been widely used in pipelines, power plant components, civil structures and so on, due to their outstanding mechanical properties as high strength and toughness, and excellent weldability. Multi-phase microstructures containing acicular ferrite or acicular ferrite dominated phase have been proved to possess good comprehensive properties in HSLA steels. This paper mainly focuses on the formation mechanisms and control methods of acicular ferrite in HSLA steels. Effect of austenitizing conditions, continuous cooling rate, and isothermal quenching time and temperature on acicular ferrite transformation was reviewed. Furthermore, the modified process to control the formation of multi-phase microstructures containing acicular ferrite, as intercritical heat treatments, step quenching treatments and thermo-mechanical controlled processing, was summarized. The favorable combination of mechanical properties can be achieved by these modified treatments.