Air cooled bainitic steels for strong, seamless pipes Part 1 – alloy design, kinetics and microstructure

Abstract

Seamless pipes are usually quenched and tempered after manufacture in order to obtain the desired properties. The possibility of avoiding this heat treatment is explored here, by designing steels which transform into an carbide free bainitic microstructure during cooling from the hot processing phase of the pipe. The cooling conditions studied are appropriate for the manufacturing process and care has been taken to ensure that the correct microstructure is generated for the range of cooling rates experienced in industrial practice. The alloy design has been validated by kinetic and microstructural studies.

Keywords:

• SEAMLESS PIPE
• BAINITE
• RETAINED AUSTENITE
• INCOMPLETE REACTION