An Investigation of Microstructural Changes of 12Cr2MoWVTiB Steel under Long Term High Temperature-Stress

The fracture surface and microstructure of 12Cr2MoWVTiB steel are investigated after a series of creep rupture tests at 620,650,670 degrees centigrade respectively.It is found that all the specimens are ruptured in the form of transcrystalline ductile fracture.
The carbides change continuously during the test,resulting in the poorness of alloy element in solid solution,decrease in the hardness of solid solution,and recrystallization.These are the main reasons why the creep rupture strength of 12Cr2MoWVTiB steel inflects.