In situ tempering of martensite during laser powder bed fusion of Fe-0.45C steel

Hearn, William; Lindgren, Kristina; Persson, Johan; Hryha, Eduard

doi:10.1016/j.mtla.2022.101459

Cited by 14 publications

(3 citation statements)

References 24 publications

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“…This finely tempered microstructure allowed the alloys to retain the high strength and hardness of martensite without noticeably reducing the ductility or toughness. The observed precipitates are likely non-transitional carbides, as previous work by Hearn et al [29]. found that the precipitates observed in plain carbon steel produced by PBF-LB related to cementite.…”

Section: Discussionsupporting

confidence: 63%

Development of powder bed fusion – laser beam process for AISI 4140, 4340 and 8620 low-alloy steel

2022

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This study focuses on process development and mechanical property evaluation of AISI 4140, 4340 and 8620 low-alloy steel produced by powder bed fusionlaser beam (PBF-LB). Process development found that increasing the build plate preheating temperature to 180°C improved processability, as it mitigated lack of fusion and cold cracking defects. Subsequent mechanical testing found that the low-alloy steels achieved a high ultimate tensile strength

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Section: Discussionsupporting

confidence: 63%

Development of powder bed fusion – laser beam process for AISI 4140, 4340 and 8620 low-alloy steel

2022

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“…First, the lower regions are continuously tempered throughout the manufacturing process. [ 37 ] Second, the heat agglomeration during build‐up affects the initial microstructure formation in the top regions. [ 29 ] This effect can be especially identified when considering the development of the etching colors for parameter VED High in Figure 8b.…”

Section: Resultsmentioning

confidence: 99%

Effect of Volumetric Energy Density and Part Height on the Material Properties of Low‐Alloyed Steels Manufactured by Laser‐Based Powder Bed Fusion of Metals

Bartels,

Novotny,

Albert

et al. 2023

Adv Eng Mater

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The layer‐by‐layer manufacturing approach in laser powder bed fusion of metals (PBF‐LB/M) leads to heat accumulation in the workpiece with increasing part heights. The effect of this heat accumulation on the resulting material properties has, however, only barely been studied for low‐alloyed steels. The goal of this work is to analyze the influence of different PBF‐LB/M‐specific boundary conditions like varying part heights and volumetric energy densities (VED) on the resulting material properties. It isfound that lower part regions possess similar hardness (380–410 HV1) and retained austenite values (7%–8%), independent of the applied VED. Higher energy inputs lead to higher retained austenite contents of up to 20% due to an incomplete transformation upon cooling. This rise in retained austenite content is also linked to a decreased material hardness down to 320 HV1. In higher part regions, this effect is reversed as the retained austenite content starts to decrease for the highest investigated VED. This is caused by the in situ preheating temperatures caused by heat accumulation, which favor a bainitic transformation. The part height‐specific properties indicate that the microstructure formation forms through a continuous transformation in lower part regions and through an isothermal transformation in higher regions.

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“…However, other recent works already showed the possibility to manufacture low alloy steels (~ 0.5 C wt. %) [6,[16][17][18][19][20][21]. The present study thus aims to provide the basis for understanding the processability of low alloy tool steel grade AISI S2.…”

Section: Development and Processability Of Aisi S2 Tool Steel By Lase...mentioning

confidence: 99%

Development and processability of AISI S2 tool steel by laser powder bed fusion

Saggionetto

2023

Materials Research Proceedings

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Abstract. Nowadays, the advantages of Laser Powder Bed Fusion (LPBF) technology attract both industry and researchers. Indeed, it is possible to build up complex geometrical parts with higher mechanical properties than those obtained by conventional methods. However, LPBF involves complex phenomena due to the high heating and cooling rates that lead to out-of-equilibrium conditions. For this reason, few metal alloys are easily processable up to now. Nevertheless, research on new steels by LPBF has been growing in recent years, in particular, regarding the development of tool steels. This work thus focuses on the development of the tool steel AISI S2 by LPBF. The process map has been investigated by varying the laser power from 100 to 250 W and the scan speed from 400 to 2000 mm/s. By combining surface analysis by means of profilometer observations, density measurements by pycnometry, defects characterization and quantification and investigations on the melt pool morphology, the best process window is selected to have fully dense, defect-free parts. Furthermore, this study allows to have comprehensive insights on the effect of the parameters on the type of defects generated during the manufacturing.

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In situ tempering of martensite during laser powder bed fusion of Fe-0.45C steel

Cited by 14 publications

References 24 publications

Development of powder bed fusion – laser beam process for AISI 4140, 4340 and 8620 low-alloy steel

Development of powder bed fusion – laser beam process for AISI 4140, 4340 and 8620 low-alloy steel

Effect of Volumetric Energy Density and Part Height on the Material Properties of Low‐Alloyed Steels Manufactured by Laser‐Based Powder Bed Fusion of Metals

Development and processability of AISI S2 tool steel by laser powder bed fusion

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