Effect of grain refinement and twin structure on the strength and ductility of Inconel 625 alloy

The yield strength levels of solid-solution strengthened nickel-based superalloys are low compared to precipitation-strengthened counterparts. Here, Inconel 625 alloy was used as a model, thermo-mechanical treatments were employed to improve the yield strength of the alloys. Compared to the as-solut...

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Published in:Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2021-08, Vol.823, p.141739, Article 141739
Main Authors: Wang, Xingmao, Ding, Yutian, Gao, Yubi, Ma, Yuanjun, Chen, Jianjun, Gan, Bin
Format: Article
Language:English
Subjects:
Alloys
Annealing
Annealing twins
Chemical precipitation
Cold rolling
Deformation
Deformation twins
Ductility
Grain boundaries
Grain refinement
Grain size
Inconel 625 alloy
Nickel
Nickel base alloys
Plastic deformation
Solid solutions
Strength-ductility synergy
Superalloys
Thermo-mechanical treatment
Thermomechanical treatment
Work hardening
Yield strength
Yield stress
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Summary:The yield strength levels of solid-solution strengthened nickel-based superalloys are low compared to precipitation-strengthened counterparts. Here, Inconel 625 alloy was used as a model, thermo-mechanical treatments were employed to improve the yield strength of the alloys. Compared to the as-solution condition, the yield strength was increased from 291 to 676 MPa with the ductility reduced from 75 to 50% after cold rolling and annealing at 1073 K for 30 min. The strength-ductility synergy originates from (1) grain boundaries and pre-existing annealing twins act as strong barriers to hinder dislocations motion, and (2) the formation of deformation twins during plastic deformation provides an extra work-hardening region to maintain the excellent ductility. The strengthening effect of annealing twins is determined by the thickness rather than the length fraction. Deformation twins tend to form in the fine-grained Inconel 625 alloy (the grain size ranging from 3.1 to 4.7 μm) during plastic deformation. This is the reason for an extra work hardening region in the hardening curve. Our present work can provide a reference for realizing the strength-ductility synergy of solid-solution strengthened nickel-based superalloys.
ISSN:0921-5093
1873-4936
DOI:10.1016/j.msea.2021.141739