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Title: Modeling Long-term Creep Performance for Welded Nickel-base Superalloy Structures for Power Generation Systems

Abstract

The goal of this project is to model long-term creep performance for nickel-base superalloy weldments in high temperature power generation systems. The project uses physics-based modeling methodologies and algorithms for predicting alloy properties in heterogeneous material structures. The modeling methodology will be demonstrated on a gas turbine combustor liner weldment of Haynes 282 precipitate-strengthened nickel-base superalloy. The major developments are: (1) microstructure-property relationships under creep conditions and microstructure characterization (2) modeling inhomogeneous microstructure in superalloy weld (3) modeling mesoscale plastic deformation in superalloy weld and (4) a constitutive creep model that accounts for weld and base metal microstructure and their long term evolution. The developed modeling technology is aimed to provide a more efficient and accurate assessment of a material’s long-term performance compared with current testing and extrapolation methods. This modeling technology will also accelerate development and qualification of new materials in advanced power generation systems. This document is a final technical report for the project, covering efforts conducted from October 2014 to December 2016.

Authors:
 [1];  [1];  [1];  [1];  [1];  [1]
  1. GE Global Research, NIskayuna, NY (United States)
Publication Date:
Research Org.:
GE Global Research, NIskayuna, NY (United States)
Sponsoring Org.:
USDOE Office of Fossil Energy (FE)
OSTI Identifier:
1345084
Report Number(s):
DOE-GE-FE24027
DUNS 08-6188401
DOE Contract Number:
FE0024027
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 24 POWER TRANSMISSION AND DISTRIBUTION; Modeling; Creep; Haynes 282; Weldment

Citation Formats

Shen, Chen, Gupta, Vipul, Huang, Shenyan, Soare, Monica, Zhao, Pengyang, and Wang, Yunzhi. Modeling Long-term Creep Performance for Welded Nickel-base Superalloy Structures for Power Generation Systems. United States: N. p., 2017. Web. doi:10.2172/1345084.
Shen, Chen, Gupta, Vipul, Huang, Shenyan, Soare, Monica, Zhao, Pengyang, & Wang, Yunzhi. Modeling Long-term Creep Performance for Welded Nickel-base Superalloy Structures for Power Generation Systems. United States. doi:10.2172/1345084.
Shen, Chen, Gupta, Vipul, Huang, Shenyan, Soare, Monica, Zhao, Pengyang, and Wang, Yunzhi. Tue . "Modeling Long-term Creep Performance for Welded Nickel-base Superalloy Structures for Power Generation Systems". United States. doi:10.2172/1345084. https://www.osti.gov/servlets/purl/1345084.
@article{osti_1345084,
title = {Modeling Long-term Creep Performance for Welded Nickel-base Superalloy Structures for Power Generation Systems},
author = {Shen, Chen and Gupta, Vipul and Huang, Shenyan and Soare, Monica and Zhao, Pengyang and Wang, Yunzhi},
abstractNote = {The goal of this project is to model long-term creep performance for nickel-base superalloy weldments in high temperature power generation systems. The project uses physics-based modeling methodologies and algorithms for predicting alloy properties in heterogeneous material structures. The modeling methodology will be demonstrated on a gas turbine combustor liner weldment of Haynes 282 precipitate-strengthened nickel-base superalloy. The major developments are: (1) microstructure-property relationships under creep conditions and microstructure characterization (2) modeling inhomogeneous microstructure in superalloy weld (3) modeling mesoscale plastic deformation in superalloy weld and (4) a constitutive creep model that accounts for weld and base metal microstructure and their long term evolution. The developed modeling technology is aimed to provide a more efficient and accurate assessment of a material’s long-term performance compared with current testing and extrapolation methods. This modeling technology will also accelerate development and qualification of new materials in advanced power generation systems. This document is a final technical report for the project, covering efforts conducted from October 2014 to December 2016.},
doi = {10.2172/1345084},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Feb 28 00:00:00 EST 2017},
month = {Tue Feb 28 00:00:00 EST 2017}
}

Technical Report:

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  • We report here a constitutive model for predicting long-term creep strain evolution in’ strengthened Ni-base superalloys. Dislocation climb-bypassing’, typical in intermediate’ volume fraction (~20%) alloys, is considered as the primary deformation mechanism. Dislocation shearing’ to anti-phase boundary (APB) faults and diffusional creep are also considered for high-stress and high-temperature low-stress conditions, respectively. Additional damage mechanism is taken into account for rapid increase in tertiary creep strain. The model has been applied to Alloy 282, and calibrated in a temperature range of 1375-1450°F, and stress range of 15-45ksi. The model parameters and a MATLAB code are provided. This report is preparedmore » by Monica Soare and Chen Shen at GE Global Research. Technical discussions with Dr. Vito Cedro are greatly appreciated. This work was supported by DOE program DE-FE0005859« less
  • The models developed, contain explicit dependences on constituent material properties and their changes with time, so that composite performance can be predicted. Three critical processes in ceramic composites at elevated temperatures have been modeled: (1) creep deformation of composite vs stress and time-dependent creep of fibers and matrix, and failure of these components; (2) creep deformation of ``interface`` around broken fibers; and (3) lifetime of the composite under conditions of fiber strength loss over time at temperature. In (1), general evolution formulas are derived for relaxation time of matrix stresses and steady-state creep rate of composite; the model is testedmore » against recent data on Ti-MMCs. Calculations on a composite of Hi-Nicalon fibers in a melt-infiltrated SiC matrix are presented. In (2), numerical simulations of composite failure were made to map out time-to-failure vs applied load for several sets of material parameters. In (3), simple approximate relations are obtained between fiber life and composite life that should be useful for fiber developers and testers. Strength degradation data on Hi-Nicalon fibers is used to assess composite lifetime vs fiber lifetime for Hi-Nicalon fiber composites.« less
  • Three superheater transition joints, between 2-1/4Cr1Mo and 316 stainless steel welded with Ni-based weld metal, removed from service after 72,337 hours, were examined using optical and scanning electron microscopy. Also, microhardness measurements were made and local chemical compositions analyzed using the EDX attachment on the scanning electron microscope. Temperature accelerated creep-rupture tests have been carried out at stresses of 31 - 62 MNm to the minus 2 power and 590 - 625 C on cross-weld tensile specimens machined longitudinally from the walls of the joints. Detailed metallographic examinations have been made to identify the fracture mode.
  • Candidate iron-base alloys for heater tube application in the Stirling automotive engine were aged at 760/sup 0/C for 3500 h in a low pressure argon or hydrogen atmosphere to determine the effect on mechanical behavior. The seven alloys evaluated were N-155, 19-9DL, 316SS, Nitronic 40, A286, Incoloy 800H, and RA330. Aging produced no appreciable changes in alloy grain size but did promote increased density and growth of precipitate particles in the grains and grain boundaries. Tensile properties were generally degraded by aging, with ductility and strength changes being influenced by grain structure. Aging also decreased creep-rupture strength, with coarse grainmore » materials being more susceptible to strength loss. The presence of hydrogen during aging did not contribute significantly to creep strength degradation in the coarse grain alloys but did result in extensive strength losses in fine grain alloys. Based on current criteria for the Mod I Stirling engine, the N-155 and 19-9DL alloys were the only alloys in this study with strengths adequate for heater tube service at 760/sup 0/C.« less
  • Many US manufacturing companies have moved fabrication and production facilities off shore because of cheaper labor costs. A key aspect in bringing these jobs back to the US is the use of technology to render US-made fabrications more efficient overall with higher quality. A new initiative of the current administration has the goal of enhancing competitiveness to retain manufacturing jobs in the US. One significant competitive advantage that has emerged in the US over the last two decades is the use of virtual design for fabrication of large structures in the light and heavy materials industries. Industries that have usedmore » virtual design and analysis tools have reduced material parts size, developed environmentally-friendly fabrication processes, improved product quality and performance, and reduced manufacturing costs. Indeed, Caterpillar Inc. (CAT), one of the partners in this effort, continues to have a large fabrication presence in the US because of the use of weld fabrication modeling to optimize fabrications by controlling weld residual stresses and distortions and improving fatigue, corrosion, and fracture performance. This report describes Engineering Mechanics Corporation of Columbus (Emc2's) DOE SBIR Phase I results which extended an existing, state-of-the-art software code, VFT, currently used to design and model large welded structures prior to fabrication - to a broader range of products with widespread applications for small and medium-sized enterprises (SMEs). VFT helps control distortion, can minimize and/or control residual stresses, control welding microstructure, and pre-determine welding parameters such as weld-sequencing, pre-bending, thermal-tensioning, etc. VFT uses material properties, consumable properties, etc. as inputs. Through VFT, manufacturing companies can avoid costly design changes after fabrication. This leads to the concept of joint design/fabrication where these important disciplines are intimately linked to minimize fabrication costs. VFT currently is tied to a commercial solver which makes it prohibitively expensive for use by SMEs, as there is a significant licensing cost for the solver - over and above for the relatively minimal cost for VFT. Emc2 developed this software code over a number of years in close cooperation with CAT (Peoria, IL), who currently uses this code exclusively for worldwide fabrication, product design and development activities. The use of VFT has allowed CAT to move directly from design to product fabrication and helped eliminate (to a large extent) new product prototyping and subsequent testing. Additionally, CAT has been able to eliminate/reduce costly one-of-a-kind appliances used to reduce distortion effects due to fabrication. In this context, SMEs can realize the same kind of improved product quality and reduced cost through adoption of the adapted version of VFT for design and subsequent manufacture of new products. Emc2's DOE SBIR Phase I effort successfully adapted VFT so that SMEs have access to this sophisticated and proven methodology that is quick, accurate and cost effective and available on-demand to address weld-simulation and fabrication problems prior to manufacture. The open source code, WARP3D, a high performance finite element code mainly used in fracture and damage assessment of structures, was modified so that computational weld problems can be solved efficiently on multiple processors and threads with VFT. The thermal solver for VFT, based on a series of closed form solution approximations, was enhanced for solution on multiple processors greatly increasing overall speed. In addition, the graphical user interface (GUI) has been tailored to integrate these solutions with WARP3D. The GUI is used to define all the weld pass descriptions, number of passes, material properties, consumable properties, weld speed, etc. for the structure to be modeled. The GUI was improved to make it user-friendly for engineers that are not experts in finite element modeling. Finally, a plan for porting VFT onto the Ohio Supercomputer Center (OSC) through its hosted Manufacturing and Polymer Portal has been developed. This access route will permit SMEs to perform weld modeling to improve their competitiveness at a reasonable cost. All of these improvements are detailed in this repo« less