Microstructure and property of a selective laser melting process induced oxide dispersion strengthened 17-4 PH stainless steel

Hsu, Tzu-Hou; Chang, Young-Il; Huang, Chi‐Yuan; Yen, Hung‐Wei; Chen, Chih-Peng; Jen, Kuo-Kuang; Yeh, An‐Chou

doi:10.1016/j.jallcom.2019.06.289

Cited by 73 publications

(29 citation statements)

References 49 publications

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“…Previous work on as-built PH SS AM components revealed a non-equilibrium microstructure, as well as strong differences in texture parallel and perpendicular to the build direction, due to the very high cooling rates [17,99,[104][105][106][107]115]. Some of the literature claimed that the as-built microstructure via L-PBF contains martensite and retained austenite (metastable phase at room temperature) [26,27,95,98,[119][120][121][122], completely different from that of a wrought 17-4 PH stainless steel, which is fully martensitic. However, Alnajjar et al [117] and Sun et al [123] respectively reported a fully δ-ferrite microstructure (based on Figure 2) and a dominantly ferrite microstructure ( Figure 3) with small grains at melt-pool boundaries comprising bcc martensitic laths and equiaxed fcc austenite grains.…”

Section: Microstructure In As L-pbfed Statementioning

confidence: 99%

“…For 17-4 PH stainless steel, the starting and ending temperatures of martensitic transformation Ms (132 • C) and Mf (32 • C) are higher than room temperature, which leads to complete transformation of austenite at room temperature [14]. For the AM specimens, the cooling rates in L-PBF are high enough to form a complete martensite structure [122]. However, some regions of martensite formed during the L-PBF process would be heat-affected by laser scanning paths, resulting in the formation of reverted austenite (inter-lath austenite).…”

Section: Microstructure In As L-pbfed Statementioning

confidence: 99%

“…In this case, the subsequent aging treatment of the material results in an increase in yield and tensile strength. With the increase in aging temperature and time, the volume percentage of austenite is as high as 20.4% [27,122]. The copper-rich precipitates can be formed within the martensite matrix during the aging process, but this does not occur spontaneously in the as-built sample.…”

Section: Microstructure After Heat Treatmentsmentioning

confidence: 99%

“…It is noteworthy that direct aging results in a high fraction of austenitic reduction, i.e., 17.9%. It is observed that these austenite grains nucleate on the grain boundaries of the slab and parent austenite [27,122]. The high-volume fraction of austenite in the as-L-PBFed state can inhibit the aging strengthening.…”

Section: Microstructure After Heat Treatmentsmentioning

confidence: 99%

“…Studies [26,122] were conducted to investigate the effect of building orientation on mechanical properties, as shown in Table 7. The results showed that the building direction has a certain influence on the monotonic stretching behavior of L-PBF 17-4 PH stainless steel.…”

Section: Tensile Propertiesmentioning

confidence: 99%

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Laser Powder Bed Fusion of Precipitation-Hardened Martensitic Stainless Steels: A Review

Zai

Zhang

Wang

et al. 2020

Metals

100

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Martensitic stainless steels are widely used in industries due to their high strength and good corrosion resistance performance. Precipitation-hardened (PH) martensitic stainless steels feature very high strength compared with other stainless steels, around 3-4 times the strength of austenitic stainless steels such as 304 and 316. However, the poor workability due to the high strength and hardness induced by precipitation hardening limits the extensive utilization of PH stainless steels as structural components of complex shapes. Laser powder bed fusion (L-PBF) is an attractive additive manufacturing technology, which not only exhibits the advantages of producing complex and precise parts with a short lead time, but also avoids or reduces the subsequent machining process. In this review, the microstructures of martensitic stainless steels in the as-built state, as well as the effects of process parameters, building atmosphere, and heat treatments on the microstructures, are reviewed. Then, the characteristics of defects in the as-built state and the causes are specifically analyzed. Afterward, the effect of process parameters and heat treatment conditions on mechanical properties are summarized and reviewed. Finally, the remaining issues and suggestions on future research on L-PBF of martensitic precipitation-hardened stainless steels are put forward.Metals 2020, 10, 255 2 of 25 types of microstructures can be obtained with different heat treatment processes [9]. The typical temperature range for aging heat treatment for this alloy is 480-620 • C [1]. Under the H900 condition (aging temperature: 482 • C, time: 1 h), the precipitation in 17-4 PH stainless steel begins with Cu-rich precipitates (bcc, body center cubic) that maintain a coherent relationship with the matrix, which would lead to an increase in tensile strength and toughness [4]. These precipitates can transform into non-coherent Cu-rich particles (fcc, face center cubic) after extended aging at 400 • C [5]. After experiencing over-aging, the precipitates are coarsened. The number of precipitates is reduced, and the coherence relationship is also destroyed [6,10]. These changes together lead to a decrease in mechanical strength, but an increase in ductility and impact toughness.PH stainless steels are widely used in the aerospace industry [11,12], the marine industry [13], nuclear reactor components [14], chemical process equipment [15], and medical apparatus due to their high tensile strength, impact strength, fracture toughness, and corrosion resistance at typical service temperatures below 300 • C [15,16]. Most of these parts are important load-bearing components of heavy machinery in a demanding service environment. However, PH stainless steels have poor workability and machinability due to their high strength and high hardness, which result in a long production cycle and difficulties in obtaining desired shapes through conventional machining and forming processes [17].Due to the high strength and high hardness of PH steels, they are difficult to b...

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Section: Microstructure In As L-pbfed Statementioning

confidence: 99%

Section: Microstructure In As L-pbfed Statementioning

confidence: 99%

Section: Microstructure After Heat Treatmentsmentioning

confidence: 99%

Section: Microstructure After Heat Treatmentsmentioning

confidence: 99%

Section: Tensile Propertiesmentioning

confidence: 99%

See 3 more Smart Citations

Laser Powder Bed Fusion of Precipitation-Hardened Martensitic Stainless Steels: A Review

Zai

Zhang

Wang

et al. 2020

Metals

100

View full text Add to dashboard Cite

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High‐Temperature Creep Properties of an Additively Manufactured Y₂O₃ Oxide Dispersion‐Strengthened Ni–Cr–Al–Ti γ/γ’ Superalloy

et al. 2022

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Oxide dispersion-strengthened (ODS) alloys combine superior mechanical properties, corrosion, and creep resistance at temperatures beyond the coarsening and dissolution limits of classical precipitation strengthening. [1][2][3] However, alloys that rely on dispersoid strengthening alone suffer from low strength at intermediate temperatures, where they are being outperformed by conventionally cast precipitation-hardened Ni-based superalloys. [2,[4][5][6] This led to the development of ODS Ni-based superalloys combining three types of strengthening (matrix solid solution, γ' precipitates, and oxide dispersoid), such as MA6000 (Ni-15Cr-4.5Al-2.5Ti-4W-2Ta-2.5Fe-1.1Y 2 O 3 , wt%), PM3030 (Ni-17Cr-6Al-2Mo-3.5W-2Ta-0.9Y 2 O 3 ), and their variants. [7][8][9][10][11] The contributions of γ' precipitates and oxide dispersoids to the creep resistance of these ODS alloys are found to be additive, making them superior to their solely precipitation-hardened counterparts. [12] However, when the precipitates are then dissolved at high temperatures, similar creep resistance is observed again between γ'and non-γ'-strengthened ODS alloys, as only the dispersoids provide resistance to creep. [8] Ultimately, ODS alloys provide superior performance compared with γ/γ' Ni-based superalloys only at medium stresses, at temperatures above γ' coarsening or dissolution temperature and when high microstructural stability is required. [13] The need for additional strength at lower temperatures stems from applications where ODS alloys are desired for the hottest part of a component but still have to fulfill specifications in sections at lower temperatures. [7] While technical feasibility has been demonstrated, ODS alloys remain a niche solution due to the costly powder metallurgy processing route, heat treatments required for microstructure adjustment, difficulties in achieving net-shaped parts, and competition from continued optimization of conventional alloys. [14,15] The challenges in processing and part complexity can be overcome by melt-based additive manufacturing (AM), either by laser powder bed fusion (L-PBF) or electron beam melting (EBM) to melt and consolidate the ODS powder, which features very short times in the liquid phase, thus helping to maintain isotropic dispersoid distribution within the solidified alloy. [16][17][18][19] As shown

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Microstructural Control of a Multi‐Phase PH Steel Printed with Laser Powder Bed Fusion

Fields,

Amiri,

Lim

et al. 2024

Adv Materials Technologies

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The established approach to materials design for additive manufacturing (AM) consists of attempting to reproduce the uniform structures and properties of conventionally processed materials. While this certainly helped facilitate material certification and the rapid introduction of AM technologies in several industries, the opportunity to exploit unique features of specific AM processes to generate spatially varying microstructures–and hence novel materials, remains largely untapped. This work presents a method for manufacturing materials through laser powder bed fusion (LPBF), in which control over the spatial variation in phase composition and mechanical properties is achieved. This technique is demonstrated using 17‐4 precipitation‐hardened stainless steel (17‐4PH), by controlling spatial modulation of energy densities during printing. This results in local control of ferrite/martensite volume fractions, allowing the fabrication of metal/metal architected composites with hard/brittle regions interspersed with soft/tough regions. Local variations of ~20% in tensile strength and ~150% in elongation are achieved, with a spatial resolution of ~100 microns. The approach is general and robust, fully compatible with commercially available LPBF equipment, and applicable to virtually any multi‐phase alloy system. This work shifts the paradigm from attempting to print components with uniform properties to manufacturing alloys with controlled spatial property gradients.

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Microstructure and property of a selective laser melting process induced oxide dispersion strengthened 17-4 PH stainless steel

Cited by 73 publications

References 49 publications

Laser Powder Bed Fusion of Precipitation-Hardened Martensitic Stainless Steels: A Review

Laser Powder Bed Fusion of Precipitation-Hardened Martensitic Stainless Steels: A Review

High‐Temperature Creep Properties of an Additively Manufactured Y₂O₃ Oxide Dispersion‐Strengthened Ni–Cr–Al–Ti γ/γ’ Superalloy

Microstructural Control of a Multi‐Phase PH Steel Printed with Laser Powder Bed Fusion

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Microstructure and property of a selective laser melting process induced oxide dispersion strengthened 17-4 PH stainless steel

Cited by 73 publications

References 49 publications

Laser Powder Bed Fusion of Precipitation-Hardened Martensitic Stainless Steels: A Review

Laser Powder Bed Fusion of Precipitation-Hardened Martensitic Stainless Steels: A Review

High‐Temperature Creep Properties of an Additively Manufactured Y2O3 Oxide Dispersion‐Strengthened Ni–Cr–Al–Ti γ/γ’ Superalloy

Microstructural Control of a Multi‐Phase PH Steel Printed with Laser Powder Bed Fusion

Contact Info

Product

Resources

About

Microstructure and property of a selective laser melting process induced oxide dispersion strengthened 17-4 PH stainless steel

High‐Temperature Creep Properties of an Additively Manufactured Y₂O₃ Oxide Dispersion‐Strengthened Ni–Cr–Al–Ti γ/γ’ Superalloy