Investigation on Microstructures of Multipass Deposited Metal for 9Cr-1Mo Ferritic Steels
The microstructures of multipass deposited metal for 9Cr-1Mo ferritic steels were investigated. Columnar martensites and a number of film austenites retained along the lath of martensite comprised primary microstructure. -ferrite was formed and the volume fraction of -ferrite increased as the chromium equivalent (Creq) of steel composition increased. Subjected to weld heating, the primary microstructure transformed. “Weld bead heat-affected zone (WBHAZ)” was thus formed. The morphology of -ferrite changed and columnar martensite grains were broken in sub-zone I and II of WBHAZ. The size and amount of -ferrite reduced because of austenitization and growth of austenite in sub-zone III of WBHAZ. Retained austenite morphology changed from film into island-like in sub-zone IV and martensite tempered to some degree in sub-zone V of WBHAZ. The precipitation and evolution of M23C6, MX and Laves phase by means of neutron diffraction is to be conducted in the future.
Y. Akiniwa, K. Akita and H. Suzuki
H.H. Wang and K. M. Wu, "Investigation on Microstructures of Multipass Deposited Metal for 9Cr-1Mo Ferritic Steels", Materials Science Forum, Vol. 652, pp. 270-274, 2010