A Study on the Thermo-Mechanical History, Residual Stress, and Dynamic Recrystallization Mechanisms in Additively Manufactured Austenitic Stainless Steels

In this work, both numerical simulations and experimental characterization were used to obtain a broad understanding of the thermo-mechanical history, residual stress, and microstructure of the directed energy deposition (DED) process of austenitic stainless steels. To investigate the effect of proc...

Full description

Saved in:
Bibliographic Details
Published in:Metals (Basel ) 2022-07, Vol.12 (7), p.1109
Main Authors: Yan, Zhou, Zou, Xi, Li, Simeng, Luo, Guoyun, Song, Lijun
Format: Article
Language:English
Subjects:
Additive manufacturing
Austenitic stainless steels
Austenitizing
Dislocation density
dislocation structure
Dynamic recrystallization
dynamic recrystallization (DRX)
finite element analysis
Grain boundaries
Lasers
Methods
Microstructure
Phase transitions
Plastic deformation
Residual stress
Sensitivity analysis
Solidification
Stainless steel
Thickness
Titanium alloys
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:In this work, both numerical simulations and experimental characterization were used to obtain a broad understanding of the thermo-mechanical history, residual stress, and microstructure of the directed energy deposition (DED) process of austenitic stainless steels. To investigate the effect of process factors on residual stress, the global sensitivity analysis approach based on D-MORPH-HDMR was utilized. The results of the research reveal that the amplified effect of the influence of the three input variables (layer thickness, L; laser power, P; and scanning speed, v) on the transverse residual stress and thickness-direction residual stress is L > P > v; in contrast, the influence of longitudinal residual stress is P > L > v. We also found that general tendencies in local plastic strain accumulation are analogous to the relative distribution of geometrically necessary dislocations (GNDs). Additionally, we investigated post-solidification structures connected to residual stress, such as submicron dislocation cells and dynamic recrystallization (DRX) in austenitic stainless steels during DED. The investigation revealed that the DDRX and CDRX phenomena were caused by the bulging of initial grain boundaries and progressive sub-grain rotation (PSR). The fact that the sample bottom had more thermo-mechanical cycles than the top led to a higher dislocation density and hence more DDRX. This study presents a unique perspective on the link between residual stress and microstructure in additive manufacturing.
ISSN:2075-4701
2075-4701
DOI:10.3390/met12071109