Title: Combined crystal plasticity and grain boundary modeling of creep in ferritic-martensitic steels: II. The effect of stress and temperature on engineering and microstructural properties

Abstract

This paper describes a series of physically-based crystal plasticity finite element method (CPFEM) simulations of long-term creep and creep rupture of Grade 91 steel. It is Part 2 of a two part series of papers. Part 1 describes the simulation framework; this part focuses on specific simulations and on how the predicted long-term creep properties of Grade 91 compare to the assumptions used in current high temperature design practices. This work extends the model developed in Part 1 to look at creep properties at different temperatures, principal stresses, and multiaxial stress states. The simulations show that empirically extrapolating creep rupture stresses from short-term experimental data may substantially over predict the actual long-term creep properties of Grade 91. Additionally, the CPFEM calculations predict a transition from notch strengthening creep behavior for high values of maximum principal stress and moderate notch severity to notch weakening behavior for low principal stresses and more severe notches. The latter regime better categorizes conditions in engineering components designed for long term elevated temperature use, which implies Grade 91 may be a notch weakening material in actual service. This would have a significant impact on high temperature design practices, though confirmatory test data on long-life, low stressmore » notched specimens is difficult to obtain. Finally, one advantage of the physically-based modeling approach adopted here is that the simulation results also elucidate the microstructural mechanisms causing the macroscopic trends in engineering properties predicted by the simulations. This paper shows that the detailed micromechanical mechanisms predicted by the CPFEM simulations can be abstracted with a simple micromechanical model that can be used to both explain the detailed results and make improved predictions of engineering properties from experimental data.« less

Authors:

Messner, M. C.  ^[1];

• Search DOE PAGES for author "Messner, M. C."
• Search DOE PAGES for ORCID "0000-0002-0040-4385"

Nassif, Omar ^[2]; Ma, Ran ^[2]; Truster, Timothy J.  ^[2];

• Search DOE PAGES for author "Truster, Timothy J."
• Search DOE PAGES for ORCID "0000-0003-3849-6788"

Cochran, Kristine; Parks, David ^[3]; Sham, T-L ^[1]

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+ Show Author Affiliations

1. Argonne National Lab. (ANL), Argonne, IL (United States). Applied Materials Division
2. Univ. of Tennessee, Knoxville, TN (United States)
3. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Dept. of Mechanical Engineering

Publication Date:

Tue Aug 20 00:00:00 EDT 2019

Research Org.:

Argonne National Lab. (ANL), Argonne, IL (United States)

Sponsoring Org.:

USDOE Office of Nuclear Energy (NE), Reactor Fleet and Advanced Reactor Development. Nuclear Reactor Technologies

OSTI Identifier:

1574948

Grant/Contract Number:  

AC02-06CH11357

Resource Type:

Accepted Manuscript

Journal Name:

Modelling and Simulation in Materials Science and Engineering

Additional Journal Information:

Journal Volume: 27; Journal Issue: 7; Journal ID: ISSN 0965-0393

Publisher:

IOP Publishing

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; cavitation; creep; crystal plasticity; grain boundary sliding; notch effects