PERFORMANCE IMPROVEMENT OF CREEP-RESISTANT FERRITIC STEEL WELDMENTS THROUGH THERMO-MECHANICAL TREATMENT AND ALLOY DESIGN

Conference · Fri Jan 01 00:00:00 EST 2016

OSTI ID:1324050

Yamamoto, Yukinori ^[1]; Babu, Prof. Sudarsanam Suresh ^[2]; Shassere, Benjamin ^[1]; Yu, Xinghua ^[1]

---

1. ORNL
2. University of Tennessee, Knoxville (UTK)

Two different approaches have been proposed for improvement of cross-weld creep properties of the high temperature ferrous structural materials for fossil-fired energy applications. The traditional creep strength-enhanced ferritic (CSEF) steel weldments suffer from Type IV failures which occur at the fine-grained heat affected zone (FGHAZ). In order to minimize the premature failure at FGHAZ in the existing CSEF steels, such as modified 9Cr-1Mo ferritic-martensitic steels (Grade 91), a thermo-mechanical treatment consisting of aus-forging/rolling and subsequent aus-aging is proposed which promotes the formation of stable MX carbonitrides prior to martensitic transformation. Such MX remains undissolved during welding process, even in FGHAZ, which successfully improves the cross-weld creep properties. Another approach is to develop a new fully ferrtic, creep-resistant FeCrAl alloy which is essentially free from Type IV failure issues. Fe-30Cr-3Al base alloys with minor alloying additions were developed which achieved a combination of good oxidation/corrosion resistance and improved tensile and creep performance comparable or superior to Grade 92 steel.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: FE USDOE - Office of Fossil Energy (FE)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1324050
• Resource Relation: Conference: 123HiMAT-2015, Sapporo, Japan, 20150629, 20150703
• Country of Publication: United States
• Language: English