Effect of Water Cooling Time on Microstructure and Properties of Water-air Cooled Bainitic Steel

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

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

Key Words：bainite steel; cooling rate; microsteucture; mechnical property

Abstract：The effect of water cooling time on the microstructure and mechanical properties of diameter with 53 mm bainitic steel bars after austenitizing at 920 ℃ was studied. The results show that the best mechanical properties are obtained by air cooling after water cooling for 20 s, with edge Rm of 1 363 MPa and AKV of 76.5 J. Rm and AKV at 1/2 radius are 1 361 MPa and 80.6 J respectively, the AKV at center is 97.5 J. Compared with the air-cooled bainite steel, the tensile strength and impact property at the edge and 1/2 radius of the 20 s water-cooled bainite steel are not greatly improved, but the impact value at the core of the bar can be greatly increased. For 20 s, the structure is bainite +ferrite+ retained austenite; Over 50 s, the microstructure is tempered martensite, bainite and a small amount of residual austenite.