Effect of Cooling Process on Microstructure and Properties of High Strength Bainite Steels

Author of the article:GUO Jianliang, CHENG Juqiang, MA Yilin

Author's Workplace：College of Materials Science and chemical Engineering, Xi'an Technological University, Xi'an 710021, China

Key Words：bainitic steel; cooling process; performance; organization

Abstract：The microstructure and mechanical properties of bainitic steel bars with different austenitizing heating and
cooling processes were studied. The results show that 准53 mm bar is heated at 920 ℃ and cooled at 200 ℃. The tensile
strength of the sample at R/2 is 1 654 MPa, and the A KV is 55.1 J. The microstructure is lat tempered martensite and a small
amount of residual austenite. The strength of the samples sampled at R/2 is 1 314 MPa and 1 379 MPa, and the impact
value A KV is 74.0 J and 71.7 J, respectively. The two cooling methods have high strength and impact value, and the
microstructure is bainitic ferrite and austenite. The cooling process of water cooling for 30 s before air cooling of 53 mm in
diameter bainite steel bars during heat treatment can refine the structure of bars and improve the strength and impact value
of bars.