首页|Effect of heat treatment on creep behavior of 316 L stainless steel manufactured by laser powder bed fusion
Effect of heat treatment on creep behavior of 316 L stainless steel manufactured by laser powder bed fusion
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NSTL
Elsevier
The objective of this study is to understand the thermal stability of microstructure and its effect on the creep behavior of additively-manufactured 316L stainless steel (AM 316L SS). Creep specimens were fabricated from rods printed by a laser powder bed fusion process. Six different heat treatments, namely 650 degrees C/1 h, 700 degrees C/1 h, 750 degrees C/1 h, 800 degrees C/1 h, 900 degrees C/1 h and 1050 degrees C/1 h were applied to the creep specimens. The heat-treated specimens were creep-tested under the same condition, 550 degrees C/275 MPa to evaluate the effect of post-build heat treatment on the creep behavior of AM 316L SS. In the temperature range of 650-750 degrees C, dislocation density within cells, and cell size and wall thickness were affected by the heat treatment, while elemental segregation at boundaries remained unchanged and Mn-enriched Si oxide particles remained stable. In the temperature range of 750-900 degrees C, concurrent changes were observed in dislocation cell structures, elemental segregation and oxide particles. The 1050 degrees C-heat treatment removed cell structures and boundary solute segregations, leading to formation of equiaxed grains; Mn-enriched Si oxide particles in the as-built specimen were replaced by more stable Mn-enriched Cr oxides. The creep life of AM 316L SS increased after the heat treatment at 650 degrees C and then decreased with increasing temperature up to 900 degrees C where cell/subgrain structures still existed. The creep rate and creep elongation followed an opposite trend. The creep rate can be correlated with the structural parameters of cell/subgrain size and cell wall/boundary thickness and can be rationalized by different strengthening mechanisms of dislocation cells and subgrains. The heat treatment affected strongly the primary and secondary creep but had a minimal effect on the tertiary creep of AM 316L SS.(c) 2021 Elsevier B.V. All rights reserved.
Additive manufacturingLaser powder bed fusion316L stainless steelCreepHeat treatmentsDISLOCATION CELL-FORMATIONSUBGRAIN SIZEHIGH-STRENGTHMICROSTRUCTURESUBSTRUCTUREAUSTENITESTABILITYSTRESSES
NSTL
Elsevier
