The fractography features of fracture of the creep tested 2,25Cr-1Mo steel in the initial
state and after the operation during 6·104 hours in the process of oil hydrocracking process
were analyzed. It was found the creep fracture occurs for the classic ductile mechanism by the
way of nucleation, growth and association of pores. Special fractographic feature of degraded
steel is large and deep holes caused by decohesion nonmetallic inclusions from the matrix.
The next feature is the big and plate disc-shaped dimples with the small micropores around
carbides on their bottom. Both types of holes were grown under the influence of hydrogen
accumulated by bulk metal during operation
