Effects of long-time service at high temperature on the material strength and J-R curve of Grade 91 steel. (1st June 2017)

• Record Type: Journal Article
• Authors: Lee, Hyeong-Yeon; Lim, Dong-Won; Jeong, Ji-Young
• Is Part Of: Engineering fracture mechanics. Volume 178(2017)
• Page Start: 445
• Page End: 456
• Publication Date: 2017-06-01
• Subjects: ASME-NH ASME Section III Division 1 Subsection NH -- CCG creep crack growth -- DHX decay heat exchanger -- ETD elevated temperature design -- FHX forced-draft sodium-to-air heat exchanger -- Gen IV generation IV -- Gr.91 Grade 91 -- J-R J-integral Resistance -- LBB Leak Before Break -- SFR Sodium-cooled Fast Reactor -- SG Steam Generator -- TS Tensile Strength -- USC Ultra Super Critical -- YS Yield Strength; Long-time service -- Grade 91 steel -- Yield strength -- Tensile strength -- Ductility -- J-R curve -- Thermal aging; Fracture mechanics -- Periodicals; Rupture, Mécanique de la -- Périodiques; Fracture mechanics; Periodicals; 620.112605
• DOI: 10.1016/j.engfracmech.2017.02.022
• Languages: English
• ISSNs: 0013-7944

Abstract

Highlights: Effects of long-time service on YS, TS and J-R curve for Grade 91 were investigated. Material test data were compared between service-exposed (73, 716 h at USC plant) and virgin Gr.91 steel. Comparisons were also made between test results and the material properties in the elevated temperature design (ETD) codes. It was shown that current ETD code overestimates the YS and TS properties for long-time service in a non-conservative manner for Gr.91 steel. Abstract: The effects of long-time service at high temperature on the material strength, ductility, and J-Resistance behavior of Mod.9Cr-1Mo (ASME Grade 91) steel were investigated based on tensile and J-R tests with virgin and service-exposed Gr.91 steel specimens. The service-exposed Gr.91 steel specimens were sampled from a tee junction in a reheat steam piping system of an ultra-supercritical (USC) plant in Korea with an accumulated operation time of 73, 716 h. Comparisons of the test data were made not only between the test results of the virgin materials and service-exposed materials but also between the test results and the material properties in the elevated temperature design (ETD) codes. These test data of yield strength (YS) and tensile strength (TS) for the virgin and service-exposed Gr.91 steel were compared with those of the ETD code, which showed that the current ETD code overestimates the YS and TS properties for long-time service in a non-conservative manner for Gr.91 steel. J-R test data currently not available in ETD codes were produced over a range of temperatures for virgin and service-exposed Gr.91 steel. The effects of long-time service in J-R curve were investigated.