This blog is the first part of a 3-blog series. To view the rest of the story click HERE for Part 2 and Here for Part 3. Part 1: History Thirty years ago, Grade 91 (9Cr-1Mo-V) steel was hailed as the savior of the power generation industry [1]; now it’s behavior has been described as […]
Read Part 1 Part 2: Type IV Cracking and Inspectability The current concerns with Grade 91 are fundamentally and firmly rooted in inspectability of Type IV damage; while sensitivity of the material can be managed (see for example [1]), Type IV cracking is perhaps the Achilles heel of Grade 91. At a high level, the […]
Read Part 1 or Read Part 2 Part 3: Allowable Stresses While inspectability has been at the center of recent concerns, other issues such as chemistry control, ductility and excessive oxidation have also come under scrutiny. Perhaps most interesting is that while all of the preceding concerns have been debated, it has also been found […]
