MICROSTRUCTURE AND MORPHOLOGY OF BAINITE OF 9Cr2Mo STEEL

The microstructure and morphology of bainite of 9Cr2Mo steel austenitized at 1 100℃ and isothermally quenched in salt bath at different temperature were studied by metallographic microscope and SEM. The observed results show that upper bainite and lower bainite of 9Cr2Mo steel are obtained after the steel has been austenitized at 1 100℃ and then been isothermally quenched in salt bath at 410℃ and 350℃ respectively. Upper bainitie ferrites nucleate at austenite gains boundary and grow toward austenite gain inner and upper bainitie carbide distribute between bainitic ferrites. Lower bainite ferrites nucleate in austenite gains and lower bainite carbide distribute between bainitic ferrites,furthermore,the angles between lower bainite carbide and the principal axis of the lower bainite are unequal.