ISSN: 1945-7553
CODEN: JTEVAB
Page Count: 8

Creep-Fatigue Interaction in T11 Boiler Tube Steel

Miller, GA
Lehigh University, Bethlehem, PA

Marder, AR
Lehigh University, Bethlehem, PA

Holt, SD
South Bay Technology, San Clemente, CA

Voorhees, HR
Materials Technology, Ann Arbor, MI

(Received 7 January 1991; accepted 9 May 1991)

Abstract

This study was undertaken to assess the damage to the mechanical properties of T1l boiler tube steel resulting from about 200 000 h of service. Test results at 1000°F show that the service exposure degrades all strength properties. Tensile strength decreased from 60 to 37 ksi, 1000-h creep strength from 33 to 17 ksi, and fatigue strength (stress ratio = 0.1, life = 200 000 cycles) from 42 to 28 ksi. Also, there was a highly deleterious creep-fatigue interaction, with only 5% fatigue damage reducing creep rupture life by up to a factor of five. Property degradation was accompanied by the formation of voids and a change in the carbide morphology. These findings demonstrate the necessity for accounting for the creep-fatigue interaction in assessing the remaining life of utility components.

Keywords:
creep, fatigue, boiler tube, steel, rupture, carbides, strength, interspersion

Paper ID: JTE12612J
DOI: 10.1520/JTE12612J
ASTM International is a member of CrossRef.