ASTM Round-Robin on Creep-Fatigue and Creep Behavior of P91 Steel

Abstract

The American Society for Testing and Materials (ASTM), through its Committee E08 on Fatigue and Fracture subcommittee E08.05 on Creep-Fatigue Crack Formation, has recently developed a new standard for creep-fatigue testing (ASTM E2714-09). This paper describes the plans and preliminary results from a round-robin being presently conducted in support and verification of this new standard. The choice of the test material (ASTM Grade P91), the design of the round-robin test matrix, and a machining plan for the specimens are described. The results of microstructural analysis, tensile testing, and creep deformation and rupture testing are also presented along with some preliminary results from creep-fatigue testing. A new analytical model for representing the creep deformation characteristics of this material is also presented and evaluated using the creep data generated as part of the round-robin program. The results of the round-robin creep-fatigue testing will be used to make appropriate modifications to the test standard.

Residual life assessment of welded joints in the girth weld root

“…This circumstance confirms the high efficiency of the structure of the kinetic equation (9). A fairly complete review of modern scientific literature on the issues of long-term destruction is given in [14][15][16][17][18][19][20].…”

A Recent Development in Creep-Fatigue Testing

“…The ILS activity proposed to underpin ASTM E2714-09 included consideration of a heat of P91 steel, with the details summarized in Table 1 [43,44]. P91 was adopted primarily because of the high interest in the steel on the part of the organizations who had volunteered to participate in the ILS.…”

“…Test matrix adopted for the ASTM E2714-09 interlaboratory study [43,44] The apparent increase in the rate of softening indicated by the tensile peak stress in the third phase is in fact a consequence of compliance change due to the development of macrocracking. A comparison of these characteristics is shown in Fig.…”

“…According to guidelines given in the new standard [15], post-test inspection comprises visual and optical examination of tested specimens to characterize their external and microstructural appearances [43,44]. Whereas specimens subjected to zero-hold-time testing exhibited multiple transgranular crack initiations and insignificant evidence of dimensional instability, visual observations indicated that with increasing hold time, there was a tendency toward increased gauge section barreling (ranging from 3 % to 20 % with increasing hold time), in particular for those tests involving heating by induction or radiation.…”