Title: Rafting-Enabled Recovery Avoids Recrystallization in 3D-Printing-Repaired Single-Crystal Superalloys

Abstract

Abstract The repair of damaged Ni‐based superalloy single‐crystal turbine blades has been a long‐standing challenge. Additive manufacturing by an electron beam is promising to this end, but there is a formidable obstacle: either the residual stress and γ/γ  ′ microstructure in the single‐crystalline fusion zone after e‐beam melting are unacceptable (e.g., prone to cracking), or, after solutionizing heat treatment, recrystallization occurs, bringing forth new grains that degrade the high‐temperature creep properties. Here, a post‐3D printing recovery protocol is designed that eliminates the driving force for recrystallization, namely, the stored energy associated with the high retained dislocation density, prior to standard solution treatment and aging. The post‐electron‐beam‐melting, pre‐solutionizing recovery via sub‐solvus annealing is rendered possible by the rafting (i.e., directional coarsening) of γ  ′ particles that facilitates dislocation rearrangement and annihilation. The rafted microstructure is removed in subsequent solution treatment, leaving behind a damage‐free and residual‐stress‐free single crystal with uniform γ  ′ precipitates indistinguishable from the rest of the turbine blade. This discovery offers a practical means to keep 3D‐printed single crystals from cracking due to unrelieved residual stress, or stress‐relieved but recrystallizing into a polycrystalline microstructure, paving the way for additive manufacturing to repair, restore, and reshape any superalloy single‐crystal product.

Authors:

Chen, Kai  ^[1];

• Search DOE PAGES for author "Chen, Kai"
• Search DOE PAGES for ORCID "0000-0002-4917-4445"

Huang, Runqiu ^[1]; Li, Yao ^[2]; Lin, Sicong ^[1]; Zhu, Wenxin ^[1]; Tamura, Nobumichi  ^[3];

• Search DOE PAGES for author "Tamura, Nobumichi"
• Search DOE PAGES for ORCID "0000-0002-3698-2611"

Li, Ju  ^[4];

• Search DOE PAGES for author "Li, Ju"
• Search DOE PAGES for ORCID "0000-0002-7841-8058"

Shan, Zhi‐Wei  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-4533-0869"

Ma, Evan  ^[5]

• Search DOE PAGES for author "Ma, Evan"
• Search DOE PAGES for ORCID "0000-0002-7468-4340"

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+ Show Author Affiliations

1. Xi'an Jiaotong Univ., Shaanxi (China). Center for Advancing Materials Performance from the Nanoscale State Key Laboratory for Mechanical Behavior of Materials
2. Chang'an University, Xi'an, Shaanxi (China)
3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)
4. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
5. Johns Hopkins Univ., Baltimore, MD (United States)

Publication Date:

Thu Feb 20 00:00:00 EST 2020

Research Org.:

Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES); National Natural Science Foundation of China (NSFC); National Key Research and Development Program of China; National Science Foundation (NSF)

OSTI Identifier:

1807476

Alternate Identifier(s):

OSTI ID: 1600845

Grant/Contract Number:  

AC02-05CH11231; 91860109; 51901026; 2016YFB0700404; DE‐AC02‐05CH11231

Resource Type:

Accepted Manuscript

Journal Name:

Advanced Materials

Additional Journal Information:

Journal Volume: 32; Journal Issue: 12; Journal ID: ISSN 0935-9648

Publisher:

Wiley

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE