The effects of fabrication atmosphere condition on the microstructural and mechanical properties of laser direct manufactured stainless steel 17-4 PH

Wang, D.; Chi, Changtai; Wang, W.Q.; Li, Y.L.; Wang, M.S.; Chen, X.G.; Chen, Z.H.; Cheng, Xiangping; Xie, Yanhui

doi:10.1016/j.jmst.2019.03.009

Cited by 45 publications

(41 citation statements)

References 24 publications

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“…The atmosphere in which AM is carried out has also been shown to affect the properties of AM 17-4 PH stainless steel. A study into the effect of building atmosphere on mechanical properties of 17-4 PH stainless steel when produced by directed energy deposition (DED), an AM technique where the metal powder is fed directly into the melt pool without the need to form a powder bed, has been conducted by Wang et al [148]. Two chamber atmospheres have been considered in this study, Ar and air.…”

Section: -4 Ph Stainless Steelmentioning

confidence: 99%

Additive manufacturing of steels: a review of achievements and challenges

et al. 2020

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Metal additive manufacturing (AM), also known as 3D printing, is a disruptive manufacturing technology in which complex engineering parts are produced in a layer-by-layer manner, using a high-energy heating source and powder, wire or sheet as feeding material. The current paper aims to review the achievements in AM of steels in its ability to obtain superior properties that cannot be achieved through conventional manufacturing routes, thanks to the unique microstructural evolution in AM. The challenges that AM encounters are also reviewed, and suggestions for overcoming these challenges are provided if applicable. We focus on laser powder bed fusion and directed energy deposition as these two methods are currently the most common AM methods to process steels. The main foci are on austenitic stainless steels and maraging/precipitation-hardened (PH) steels, the two so far most widely used classes of steels in AM, before summarising the state-of-the-art of AM of other classes of steels. Our comprehensive review highlights that a wide range of steels can be processed by AM. The unique microstructural features including hierarchical (sub)grains and fine precipitates induced by AM result in enhancements of strength, wear resistance and corrosion resistance of AM steels when compared to their conventional counterparts. Achieving an acceptable ductility and fatigue performance remains a challenge in AM steels. AM also acts as an intrinsic heat treatment, triggering ‘in situ’ phase transformations including tempering and other precipitation phenomena in different grades of steels such as PH steels and tool steels. A thorough discussion of the performance of AM steels as a function of these unique microstructural features is presented in this review.

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Section: -4 Ph Stainless Steelmentioning

confidence: 99%

Additive manufacturing of steels: a review of achievements and challenges

et al. 2020

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“…The hexagon pattern is the default scan strategy for three-dimensional (3D) system metal printers. 2 Concentric pattern ("concentric") consists of successive outlines of the part. In this case, the outer perimeter of the part is processed by the laser first, and the outlines move successively inward toward the center of the part.…”

Section: Gas-atomizedmentioning

confidence: 99%

“…Precipitation-hardened (PH) stainless steels (for example, 17-4 PH steel, ≤0.07 C, 15-17.5 Cr, 3-5 Ni, 3-5 Cu, ≤1 Mn, Si, 0.15-0.45 Nb, balance Fe in wt.%) were invented to meet the demand of the rapid development of the aerospace industry since the 1940s [1,2]. They have much higher strength than ferritic or austenitic stainless steels [3].…”

Section: Introductionmentioning

confidence: 99%

“…Additive manufacturing (AM) processes [18][19][20][21][22][23][24]] offer great new opportunities for producing high-strength PH steel parts with high geometric complexity [25]. Some metal AM processes are used for printing PH steel parts, including laser powder bed fusion (L-PBF) [17,26,27], wire arc additive manufacturing (WAAM) [28][29][30][31], and direct metal laser deposition (DMLD) [2]. Compared with L-PBF, the printing accuracy of DMLD is limited by the convergence size of the powder flow, and the forming accuracy of DLMD is lower than that of L-PBF.…”

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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

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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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“…They found that the bainite morphologies depend on the laser power and the sample fabricated at 2000 W had the highest mean microhardness and the best combination of ultimate tensile strength and elongation. Wang et al [8] studied the effect of fabrication atmosphere condition on microstructure and mechanical properties of DLMD-manufactured stainless steel 17-4 PH, and they found that the samples produced in air possessed higher tensile strength and hardness than that in Ar chamber condition. The observed effect can be attributed to the amorphous oxide dispersed particles in the samples which were deposited in air.…”

Section: Introductionmentioning

confidence: 99%

Effect of laser power and deposition environment on the microstructure and properties of direct laser metal-deposited 12CrNi2 steel

Ebrahimnia¹,

Xie²,

Chi

2019

Acta Metall. Sin. (Engl. Lett.)

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Direct laser metal deposition was used for preparing blocks of steel 12CrNi2 using four different laser powers under two different deposition environments including atmospheric environment and Ar-protected chamber. The results showed that microstructures and mechanical properties were significantly affected by different laser powers. Increasing laser power and deposition in Ar chamber will lead to a decrease in the quantity and size of the voids, which brings more elongation to the samples. Bainitic microstructure was replaced by Widmanstatten ferrite and pearlite, and the amount of proeutectoid ferrite increased with increasing laser power. Moreover, microstructures of previous layers were completely altered in high laser power. Excessive heat accumulation by using high heat input can produce equiaxed ferritic grains with the pearlites in previously deposited layers. Hardness of deposited samples increased from the bottom layer toward the top layer. By using a diode laser with a spot diameter size of 2 mm, the 900-W laser power is suitable for producing crack-and void-free samples. However, post-deposition heat treatment is necessary for obtaining homogeneous desired microstructure and grain size in the manufactured samples.

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The effects of fabrication atmosphere condition on the microstructural and mechanical properties of laser direct manufactured stainless steel 17-4 PH

Cited by 45 publications

References 24 publications

Additive manufacturing of steels: a review of achievements and challenges

Additive manufacturing of steels: a review of achievements and challenges

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

Effect of laser power and deposition environment on the microstructure and properties of direct laser metal-deposited 12CrNi2 steel

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