A re-examination of the B0 and BS temperatures of steel

✍ Scribed by Zhenbo Zhao; Xin Guan; Chujie Wan; Cheng Liu; Derek O Northwood

• Book ID: 104314303
• Publisher: Elsevier Science
• Year: 2000
• Weight: 129 KB
• Volume: 21
• Category: Article
• ISSN: 0261-3069
• DOI: 10.1016/s0261-3069(99)00064-3

✦ Synopsis

Ž

. Ž A new explanation of the physical significance of the B the theoretical upper temperature limit and the B the practical 0 S . upper temperature limit temperatures in steel is proposed. It is found that the B temperature of the bainite reaction in steel 0 should be defined by the point of intersection between the thermodynamic equilibrium curve of austenite ª ferrite transforma-Ž . Ž © tion by coherent growth curve Z and the thermodynamic equilibrium curve of austenite ª cementite transformation curve ␥ ª ␣ . ES in the Fe᎐C phase diagram . The B temperature for the bainite reaction is approximately 50 ; 55ЊC lower than the B S 0 temperature. Using this method, the B and B temperatures for plain carbon steel were found to be 630ЊC and 680ЊC, S 0 Ž . respectively. The effects of steel composition on the B temperature are discussed. The formula B ЊC s 630 y 45 Mn y 40 S S Vy 35 Si y 30 Cr y 25 Moy 20 Niy 15 W can be used to predict the B temperature of a wide range of commercial steels.