Next Article in Journal
Effect of Austempering Temperature on Stress Corrosion Resistance of 52CrMoV4 Spring Steel
Previous Article in Journal
Advances in Integrated Extraction of Valuable Components from Ti-Bearing Slag
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Metals
Volume 15
Issue 10
10.3390/met15101082
metals-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Corrosion Resistance Properties of As-Sintered 17-4 PH Samples Additive-Manufactured Through Binder Jetting

by
Pietro Forcellese
1,*,
Wasiq Ali Khan
1,
Tommaso Mancia
2,
Michela Simoncini
3,
Matěj Reiser
4,
Milan Kouřil
4 and
Tiziano Bellezze
1,*
1
Department of Science and Engineering of Matter, Environment, and Urban Planning, Polytechnic University of Marche, Via Brecce Bianche, 60131 Ancona, Italy
2
Department of Theoretical and Applied Sciences, eCampus University, Via Isimbardi, 10, 22060 Novedrate, Italy
3
Department of Industrial Engineering and Mathematical Science, Polytechnic University of Marche, Via Brecce Bianche, 60131 Ancona, Italy
4
Department of Metals and Corrosion Engineering, University of Chemistry and Technology in Prague, 160 00 Prague, Czech Republic
*
Authors to whom correspondence should be addressed.
Metals 2025, 15(10), 1082; https://doi.org/10.3390/met15101082 (registering DOI)
Submission received: 31 March 2025 / Revised: 17 September 2025 / Accepted: 19 September 2025 / Published: 27 September 2025
(This article belongs to the Section Corrosion and Protection)
Browse Figures
Review Reports Versions Notes

Abstract

The corrosion resistance and microstructural characteristics of 17-4 PH stainless steel fabricated through Metal Binder Jetting (MBJ) were investigated through Cyclic Potentiodynamic Polarization (CPP), Open Circuit Potential (OCP) monitoring, SEM-EDX, optical microscopy, XRD, and chemical etching. Electrochemical tests revealed that as-sintered samples exhibited isotropic corrosion performance across different build-up orientations and directions. The CPP tests indicated the formation of a passive film with limited stability, while the monitoring of the OCP showed initial instability, followed by stabilization over time. Microstructural analysis indicated the presence of microporosities and a structure consisting of martensitic and ferritic grains in the as-sintered 17-4 PH, alongside copper and niobium segregations at grain boundaries, which may deeply influence localized corrosion susceptibility. These findings suggest that the as-sintered 17-4 PH fabricated through MBJ exhibits comparable corrosion behavior to 17-4 PH additive-manufactured through other techniques in which the sintering process is involved. The study highlights the influence of microstructure on electrochemical performance and underscores the need for post processing treatments to enhance corrosion resistance.

1. Introduction

The most common metal Additive Manufacturing (AM) technologies on the market are laser-based or electron-based systems, including Powder Bed Fusion (PBF) and Direct Energy Deposition (DED), which together accounted for 70% of the metal AM market in 2020 [1]. Contrary to these common AM systems in which powders are melted using a beam to directly build parts while printing, Metal Binder Jetting (MBJ) metals and alloys are fabricated in different steps. The MBJ printing process consists of the deposition of a liquid polymeric binder over a layer of metal powders. A printhead typically sprays a binder, then a recoater, or roller, deposits a new layer of powder onto the build platform, followed by the application of the binder. This process continues until the green part, a composite structure of metal powders bound by the polymer, is entirely fabricated. After printing, the resulting green parts undergo further steps to reach the required mechanical properties of metals and alloys. This process includes curing the polymer, depowdering the loosened powders, debinding the polymer, and finally sintering at a temperature close to the melting point of the specific material [2,3].
MBJ has recently gained attention as an efficient and cost-effective alternative AM technology for producing metals and alloys without needing high-energy beams [4,5,6,7]. Another aspect worth considering is the recyclability of metal powders in MBJ, which is paramount for sustainable manufacturing. Studies on powder reuse show that while recycled powders exhibit slight variations in particle size distribution and flowability, their impact on mechanical properties remains limited [8,9].
However, despite these advantageous characteristics, MBJ is less widely adopted than PBF and DED systems, mostly due to the lower mechanical properties of the sintered parts. This limitation is primarily caused by the porosity left after the sintering process, which remains a technological challenge to overcome for broader industrial adoption [10,11,12,13]. As the printing process of MBJ does not involve powder melting, the materials fabricated using this technology are characterized by porosities and complex microstructures. Specifically, the interaction between powder and binder is crucial in determining the mechanical properties and integrity of the parts [14,15]. Debinding and sintering are particularly critical as they influence shrinkage, densification, and microstructure [2,16]. Although MBJ can produce near-net-shape parts with isotropic properties, they require optimization through post-processing treatments to improve strength and surface finish. The binder content and saturation also significantly influence the green part strength and dimensional stability [15,17,18,19,20].
In contrast to MBJ, laser-based and electro-based AM systems produce stainless steel parts with anisotropic microstructural properties that depend on the build direction, directly affecting both mechanical and corrosion performance [21,22]. The heat source of these technologies induces significant thermal gradients due to repeated heating and cooling cycles. This leads to a heterogeneous stainless steel microstructure, characterized by grains elongated preferentially along the build direction, residual stress, and segregations [23]. Although additive-manufactured stainless steel can outperform the corrosion resistance properties of parts fabricated using subtractive metallurgy processes, the build direction significantly influences the corrosion behavior of stainless steel, with parts fabricated parallel to the build plate generally exhibiting superior corrosion performance [24,25].
Corrosion resistance is critical in determining the effective applicability of additive-manufactured components. Previous studies [26,27,28] investigated the localized corrosion resistance of 17-4 PH stainless steel fabricated using Material Extrusion (ME). They reported lower properties of the passive film than wrought material and significant variations based on build orientation and heat treatments. Strategies that have proven to improve corrosion resistance properties of sintered stainless steel include post-processing heat treatments such as solution-annealing and aging [27,28]. Similar concerns can be translated to MBJ since the microstructure resulting from the sintering process is similar to that of ME [29,30]. Austenitic stainless steel produced through MBJ displayed inconsistent corrosion resistance behavior in a neutral pH sodium chloride environment. While the as-built (unground, unpolished) 316L samples exhibited transpassive behavior, the same samples showed increased susceptibility to pitting corrosion compared to wrought counterparts after the grinding procedure [31,32]. In contrast, in a highly acidic environment, both as-built and polished 316L samples exhibited higher corrosion resistance properties than those of a wrought [33].
In light of the above, while MBJ remains a promising AM technique, its widespread adoption remains hindered by the need to optimize binder formulations, sintering conditions, and post-processing treatments, especially concerning the role of the microstructure. The present study aims to address these challenges, focusing on the localized corrosion resistance properties of MBJ-produced 17-4 PH stainless steel in neutral pH sodium chloride solutions, as it is widely adopted as a structural material in aerospace, oil and gas, and biomedical industries. The main goal of this study is to evaluate the influence of different build-up orientations and directions by characterizing the microstructural properties and electrochemical behavior of the passive film in 17-4 PH stainless steel fabricated through MBJ, thereby addressing the current knowledge gap and advancing the understanding of its industrial applicability.

2. Materials and Methods

In this study, 17-4 PH stainless steel as-sintered samples were fabricated through Binder Jetting AM technology, with various build-up orientations and directions, as illustrated in Figure 1. The printing process was performed using the Shop System (Desktop Metal, Burlington, MA, USA), with a layer thickness set at 75 µm. The printhead roller operated with a transverse speed of 75 mm∙s−1 and a rotational speed of 330 rpm. Regarding binder saturation, the components were divided into different regions, with the saturation values defined in the proprietary software that controls the binder deposition pattern. The actual binder saturation values (expressed as deposited volume percentage) were 61% in the top and shell, 38% in the inner region, and 31% in the bottom. After printing, the green parts were depowdered and handled using the Powder Station from Desktop Metal. Before sintering, the samples underwent a curing step in the Drying Oven, also available on the same platform. The samples underwent a single thermal cycle combining debinding and sintering, carried out in the Shop System furnace (Desktop Metal) under an inert gas atmosphere of 97% argon and 3% hydrogen, ensuring slightly reductive conditions. The sintering step reached a peak temperature of 1300 °C at a pressure of 17 torr. The thermal profile could not be displayed or adjusted, as it was predefined by the Shop System, which runs an algorithm to optimize binder removal and promote densification for achieving the desired mechanical properties.
Figure 1 shows the seven squared plates investigated in this study, with a side length of 25 mm and a thickness of 10 mm. The samples were fabricated by combining three build-up orientations (0°, 45°, and 90°), concerning the build plate (XZ plane) and labeled as A, and three build-up directions (0°, 45°, and 90°), concerning the printhead direction (XY plane) and labeled as B.
The squared side (25 × 25 mm) of these samples was ground to 1200 grit using emery paper and then cleaned in a sonicator with water for 5 min, followed by 15 min with normal-hexane. Before performing the electrochemical tests, the samples were left to rest for 24 h. Then, a polyimide tape was applied to the ground side of the samples, leaving an exposed area of 2 cm2 for the electrochemical tests. At least three repetitions were performed for each build-up orientation and direction investigated through the electrochemical methods considered in this study.
The Cyclic Potentiodynamic Polarization (CPP) was carried out at room temperature using a Gamry Reference 600 and Interface 1010 potentiostat (Gamry Instruments, Warminster, PA, USA) in a neutral pH 0.35 wt.% sodium chloride electrolyte using a three-electrode cell configuration. The working electrode was the tested as-sintered sample, a Saturated Calomel Electrode (SCE, E = 0.241 V vs. SHE) was used as the reference electrode, and a titanium-activated wire was used as the counter electrode. The CPP curves were performed, with a forward and reverse scan rate of 83 μV s−1, starting at 175 mV negative to the free corrosion potential and going towards positive potentials until the current density reached 0.1 mA·cm−2; then, the scan was reversed until current densities were close to those of passivation conditions, recorded during the forward scan. The working electrode potential was recorded for 30 min before the test. Furthermore, the electrochemical impedance spectroscopy was carried out before recording the CPP curves, over a frequency range of 100 kHz to 1 Hz with 10 points per decade and an applied signal amplitude of 10 mV for determining the electrolyte resistance to correct the curves from the ohmic drop. After the tests, the corrosion current density (icorr) was estimated using the Tafel model using Gamry Echem Analyst 2 software. Optical microscopy was conducted after the CPP measurements to observe whether pitting or crevice forms of localized corrosion occurred on the surface of the tested sample.
Open circuit potential (OCP) monitoring was conducted on the as-sintered samples at a controlled temperature of 30 ± 0.1 °C in a neutral pH 3.5 wt.% sodium chloride electrolyte for 96 h. The potential readings were recorded every 2.5 min using an SCE as a reference electrode and an Agilent Data Switching Unit—Model 34970A equipped with a multiplexer module—Model 34901A (Agilent, Santa Clara, CA, USA). Also, a 17-4 PH wrought sample (Wr) was investigated in the OCP monitoring to compare the electrochemical stability of the passive film with that of the as-sintered samples fabricated through MBJ. The OCP analysis was performed between 24 and 96 h using a numerical procedure to assess the passive film instability, following the same methodology described in a previous study [27]. Baseline points corresponding to steady-state conditions were identified, and a nonlinear regression curve was used to interpolate these values. Activation events exceeding a threshold of −10 mV relative to the baseline were integrated using the trapezoidal rule to quantify the instability of the passive film, or the area of these events expressed in [mV·h].
The microstructural characterization was performed on as-sintered 17-4 PH using a procedure similar to that of a previous study [27]. However, only the A0B0 sample is shown in this study, as it was considered representative of the build-up orientations and directions. Scanning Electron Microscopy (SEM) (Carl Zeiss Microscopy GmbH, Jena, Germany) with Energy-Dispersive X-ray Spectroscopy (EDX) (Bruker Nano GmbH, Berlin, Germany) was conducted on the samples, polished to 1 µm using spray monocrystal diamond powders, to assess grain structure, inclusions, segregations, and porosity. SEM-EDX analyses were performed using the Backscattered electron detector, at a voltage of 15 kV, with a working distance of 9 mm and an aperture size of 60 μm. X-ray Diffraction (XRD) was conducted on A0B0 as-sintered samples ground to 1200 grit, to evaluate the phase composition, distinguishing between ferritic and austenitic structures. The XRD measurements were carried out using a Bruker D8 Advance diffractometer (Bruker, Billerica, MA, USA) with monochromatic Cu-Kα radiation (λ = 1.54 Å), scanning over a 2θ range from 30° to 80°. Kalling’s reagent (1.5 g of copper chloride in 33.3 mL of water, 33.3 mL of ethanol, and 33.3 mL of hydrochloric acid) and Vilella’s reagent (1 g of picric acid in 100 mL of ethanol and 5 mL of hydrochloric acid) were used to etch the surface of the A0B0 as-sintered samples polished to 1 µm with spray monocrystal diamond powders, to reveal microstructural features that were observed using optical microscopy.
The chemical composition of the as-sintered A0B0 sample, ground to 1200 grit using emery paper and then cleaned by sonication in deionized water for 5 min, was analyzed at six points using a Spark Analyzer (Spectrolab, Sylmar, CA, USA).

3. Results and Discussion

The chemical composition of the as-sintered A0B0 sample fabricated through MBJ is reported in Table 1. The values are consistent with those of a typical wrought 17-4 PH stainless steel.
The XRD diffractogram shown in Figure 2 of the as-sintered A0B0 sample reveals the presence of only BCC phase peaks commonly attributed to martensite and ferrite in stainless steel. In contrast, a typical wrought sample displays both Face-Centered Cubic (FCC) and Body-Centered Cubic (BCC) peaks, although retained austenite (BCC) represents just a small fraction in volume, as observed in a previous study [27]. This suggests the sintering process leads to different microstructures rather than those typically observed for wrought samples.
Moreover, the absence of residual austenite in sintered stainless steel has been attributed to different factors in the existing literature: the presence of H2 gas in the sintering chamber together with pores and heterogeneities characterizing grain boundaries, which both foster the ferrite formation in place of the austenite [34]; the transformation of austenite to martensite at room temperature, or below 912 °C, due to slow cooling rates after sintering [35,36]; the sintering temperature above 1200–1300°C [36,37]; and the low carbon content of the stainless steel [38]. On the other hand, the formation of a secondary phase of ferrite is common in sintered stainless steel, and it has mainly been caused by the segregation of ferrite-stabilizing elements such as Cr due to the slow cooling rates after sintering [36,39,40,41,42,43].
The microstructure of A0B0, revealed using Kalling’s and Vilella’s reagents, as shown in Figure 3, highlights the typical features of sintered stainless steel. The darker grains revealed using Kalling’s (Figure 3a) etchant are characteristic of martensitic grains, in agreement with observations made in other studies on samples fabricated through ME, MBJ, and material injection molding [27,34,35,38,44]. Despite the absence of a typical wrought martensitic microstructure, the similarity to a previous study conducted on an ME technique (i.e., Bound Metal Deposition) suggests a mixed martensitic and ferritic microstructure [27]. When Vilella’s etchant is used (Figure 3b), oxides, carbides, segregations, and inclusions appear on the surface, particularly at grain boundaries. However, their precise identification using the optical microscopy technique remains uncertain. These features are consistent with those observed in a previous study [27] on as-sintered 17-4 PH stainless steel fabricated through ME, although the surface seems to be less affected by inclusions and porosities.
The SEM-EDX investigations using the backscattered electron detector conducted on the A0B0 sample shown in Figure 4a confirm the presence of two distinct grains: ferrite and martensite. Furthermore, the average chemical composition analyzed through EDX, obtained using the points labeled in Figure 4a (1, 2, and 3 for the martensitic grains; 4, 5, and 6, for the ferritic grains), and shown in Table 2, suggests the presence of ferritic grains that are enriched in chromium (~22 wt.%) and depleted in nickel (~2 wt.%) and copper (~1 wt.%). In contrast, the martensitic grains exhibit the typical chemical composition of 17-4 PH (Cr = 15–16 wt.%; Ni = 4 wt.%; Cu = 4 wt.%). These results are consistent with those observed for as-sintered 17-4 PH fabricated through ME in a previous study [27]. Small porosities, a few micrometers in diameter, are also visible as shown in Figure 4a. The elements present on the surface (Cr, Cu, and Nb) were mapped on a magnified image (Figure 4b) of the SEM investigation, and shown in Figure 4c. The elemental map highlights copper and niobium segregations, with copper found predominantly within ferritic grains and along porosities and niobium segregated at grain boundaries.
The CPP curves shown in Figure 5 indicate a corrosion behavior similar to that of as-sintered 17-4 PH samples fabricated using the ME technique, as reported in a previous investigation [26]. The corrosion potential of the samples fabricated through MBJ varied from −115 mV to −150 mV, which is the same interval as the as-sintered 17-4 PH printed using ME technology [26]. None of the CPP curves displayed a distinct anodic passive region, typical of stainless steel in neutral sodium chloride solutions, except for a limited passive region near −0.1 V to 0 V, thus, it was not possible to determine a localized breakdown potential. Unlike the results obtained on 17-4 PH printed by ME, the repassivation potential is always above the corrosion potential, suggesting a better corrosion resistance than that of as-sintered ME samples. Moreover, no significant differences in passive behavior were observed among the tested samples, suggesting an isotropic corrosion performance in different build-up orientations and directions.
Although significant differences can be observed in the average values of icorr shown in Figure 6, these values range between 0.1 and 0.9 µA·cm−2, comparable to those of wrought and as-sintered stainless steel passive films in neutral pH sodium chloride solutions, as reported in another study on as-sintered 17-4 PH fabricated through ME technology [26], in which they ranged between 0.04 and 0.15 µA·cm−2. This indicates that a protective passive film may still form on the material surface despite the absence of a clear anodic passive trait of the CPP curves.
The optical microscopy observations conducted after the CPP tests and shown in Figure 7 indicate the presence of localized forms of corrosion. Crevice corrosion is evident along the edges of the polyimide tape (Figure 7a), and similar forms of corrosion were observed across all samples. Localized corrosion attacks are visible in Figure 7b–d. It is uncertain whether pitting or crevice corrosion affected the surface, due to the lack of a distinct anodic passive trait and pitting potential in CPP curves. Porosities and segregations, such as copper and niobium, may initiate these localized corrosion attacks [26,27,45,46], but it is unclear which is mainly responsible. Figure 7e reveals a printing pattern consisting of porosities, though its impact on corrosion resistance is not well-defined since no significant electrochemical differences were observed among the samples.
The OCP monitoring of the most representative wrought and as-sintered 17-4 PH samples (Figure 8) reveals initial instability in as-sintered plates compared to the wrought, particularly in the first 6–12 h, where negative activation peaks were frequent (Figure 8a–c). The passive film instability can be caused by the copper and niobium segregations, which may also explain the active-like behavior observed in CPP tests (Figure 5) and the differences in the average values of icorr shown in Figure 6. Evidences in the existing literature suggest that the segregations, such as copper and niobium, play a dominant role from atomic to micro scales in the initiation of localized corrosion in stainless steel, particularly when they are combined with other microstructural features such as porosities [47,48].
However, after 24 h (Figure 8d–f), activation events in as-sintered samples significantly decreased, and their OCP trends became more stable, approaching that of wrought 17-4 PH. This further confirms the formation of a passive film, which correlates with the low icorr values observed in Figure 6. The OCP stabilization trend is deeply related to the passive properties of as-sintered stainless steel. This hypothesis is supported by a previous study [28], which proved that a clear anodic passive trait is observed in as-sintered 17-4 PH fabricated through ME following a long-term OCP monitoring, though an active-like behavior after 30 min of immersion in neutral pH sodium chloride electrolyte [26]. Notably, sample A45B45 (Figure 8e) exhibits a significantly nobler corrosion potential with higher activation events, compared to wrought and as-sintered samples, suggesting higher instability of the passive film over time. A similar trend toward nobler potential was observed in a previous study [26], where numerous activation events occurred during the OCP, suggesting that this behavior may be related to a higher instability of the passive film.
The quantitative analysis of the OCP in Figure 9 confirms no significant differences among the wrought and as-sintered samples. The average values of the areas are representative of the instability of the passive film or the area of the activation events expressed in [mV·h]. The average values of the area of the as-sintered samples closely match those of wrought 17-4 PH, indicating that, after 24 h, the instability of the passive film becomes comparable to that of wrought stainless steel. While A45B45 shows a higher instability, no surface corrosion was observed through optical microscopy, suggesting that these variations may not be practically significant. The standard deviation of A45B45 further suggests occasional but non-systematic instability.
Overall, the combined electrochemical tests indicate that the as-sintered 17-4 PH stainless steel exhibits isotropic corrosion resistance properties, with behavior comparable to that of a wrought 17-4 PH. The microstructure, consisting of ferrite and martensite grains along with niobium and copper segregations, influences the electrochemical behavior of the as-sintered samples examined in this study. While porosities are present, their effect on corrosion resistance remains unclear. A previous study [26] suggested that porosities negatively affect the corrosion resistance of as-sintered material, although they were found to be more abundant and their size was higher than those observed in this work. However, in this study, the limited electrochemical differences suggest that other microstructural factors, such as phase distribution and segregation, may play a more dominant role, according to another study [27].
The corrosion mechanisms remain uncertain, but the presence of copper and niobium segregations along grain boundaries and within ferritic grains may serve as potential initiation sites for localized attack, particularly when these segregations are found near porosities. Further studies, such as localized electrochemical techniques or microstructural investigations, along with post-processing heat treatments, may help clarify the role of these segregations in corrosion initiation and improve the corrosion resistance properties of the material.

4. Conclusions

The corrosion resistance properties of as-sintered 17-4 PH stainless steel additive-manufactured by the Metal Binder Jetting (MBJ) technique with different build-up orientations and directions were evaluated through Cyclic Potentiodynamic Polarization (CPP) and Open Circuit Potential (OCP) monitoring in neutral sodium chloride environments. The microstructural properties were evaluated as well through X-ray Diffraction, Scanning Electron Microscopy (SEM) with Energy-Dispersive X-ray Spectroscopy (EDX), and chemical etching, to establish the connection of these features with the corrosion resistance properties.
The results suggest that the as-sintered stainless steel exhibits isotropic corrosion behavior, as no significant differences were observed in the localized corrosion resistance properties among the samples fabricated with different build-up orientations and directions. The electrochemical behavior of the as-sintered samples, while atypical compared to conventional stainless steel, indicates the presence of a passive film.
The OCP analysis highlighted an initial period of instability in the as-sintered samples, particularly in the first 6–12 h of immersion. However, after 24 h, the potential stabilized, approaching the behavior of wrought 17-4 PH stainless steel. This suggests that the passive film undergoes modifications over time, improving its protective properties. Despite the early instability, no clear evidence of significant localized corrosion susceptibility was found across the different build-up orientations and directions, further supporting the isotropic nature of the material in terms of electrochemical response.
The microstructural analysis confirmed the presence of both martensitic and ferritic grains, along with elemental segregations and inclusions, particularly of niobium and copper. While both the mixed structure and the presence of segregations contribute to electrochemical behavior, evidence from previous studies suggests that inclusions and segregations play a key role in corrosion susceptibility and may contribute to the instability of the passive film and potentially influence localized corrosion initiation, particularly near grain boundaries and porosities. However, their specific role in the corrosion process remains unclear and requires further investigation.
A more detailed analysis of the OCP response during the first 24 h could provide additional insights into the instability of the passive film. Electrochemical impedance spectroscopy could help characterize the protective properties of the passive film, while a deeper microstructural analysis would assist in understanding the role of inclusions and segregations in corrosion initiation. Additionally, comparing these findings with results obtained from different additive manufacturing technologies and heat-treated samples would offer valuable information on how different technological factors affect corrosion behavior, guiding the optimization of processing conditions in engineering applications.

Author Contributions

Conceptualization, P.F. and T.B.; methodology, P.F., M.K. and T.B.; software, P.F. and T.B.; validation, P.F.; formal analysis, P.F., M.S., M.K. and T.B.; investigation, P.F., W.A.K. and M.R.; resources, P.F., T.M., M.S. and T.B.; data curation, P.F. and W.A.K.; writing—original draft preparation, P.F.; writing—review and editing, P.F., W.A.K., T.M., M.S., M.R., M.K. and T.B.; visualization, P.F. and T.M.; supervision, M.S., M.K. and T.B. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Data Availability Statement

The data presented in this study are available on request from the corresponding author. The data required to reproduce these findings cannot be shared, as they are part of ongoing investigations.

Acknowledgments

The authors thank Tommaso Verdini, Marco Favario, and Antonio Vulcano for their support during this research activity.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Vafadar, A.; Guzzomi, F.; Rassau, A.; Hayward, K. Advances in Metal Additive Manufacturing: A Review of Common Processes, Industrial Applications, and Current Challenges. Appl. Sci. 2021, 11, 1213. [Google Scholar] [CrossRef]
  2. Li, M.; Du, W.; Elwany, A.; Pei, Z.; Ma, C. Metal binder jetting additive manufacturing: A literature review. J. Manuf. Sci. Eng. Trans. ASME 2020, 142, 090801. [Google Scholar] [CrossRef]
  3. Dini, F.; Ghaffari, S.A.; Jafar, J.; Hamidreza, R.; Marjan, S. A review of binder jet process parameters; powder, binder, printing and sintering condition. Met. Powder Rep. 2020, 75, 95–100. [Google Scholar] [CrossRef]
  4. Kráľ, J.; Dzuro, T.; Debski, H. Applying Binder Jetting Technology to 316L Stainless Steel Materials and Testing Its Mechanical and Dimensional Properties Depending on the Printing Method. Materials 2024, 17, 4400. [Google Scholar] [CrossRef] [PubMed]
  5. Bianchi, I.; Forcellese, A.; Forcellese, P.; Mancia, T.; Mignanelli, C.; Simoncini, M.; Verdini, T. Effect of Printing Orientation Angle and Heat Treatment on the Mechanical Properties and Microstructure of Binder-Jetting-Printed Parts in 17-4 PH Stainless Steel. Metals 2024, 14, 1220. [Google Scholar] [CrossRef]
  6. Ibrahim, B.; Lopez, L.; Kulkarni, S.; Jobes, D.; Forgiarini, M.; Barber, J.R.; Gordon, J.V. Increasing strength properties in sinter-based additive manufacturing of SS316L via metal material jetting of sub-micron powders. Addit. Manuf. 2024, 89, 104268. [Google Scholar] [CrossRef]
  7. Lecis, N.; Beltrami, R.; Mariani, M. Binder jetting 3D printing of 316 stainless steel: Influence of process parameters on microstructural and mechanical properties. Metall. Ital. 2021, 113, 31–41. [Google Scholar]
  8. Mirzababaei, S.; Paul, B.K.; Pasebani, S. Metal Powder Recyclability in Binder Jet Additive Manufacturing. Jom 2020, 72, 3070–3079. [Google Scholar] [CrossRef]
  9. Lanzutti, A.; Marin, E. The Challenges and Advances in Recycling/Re-Using Powder for Metal 3D Printing: A Comprehensive Review. Metals 2024, 14, 886. [Google Scholar] [CrossRef]
  10. Xu, M.; Guo, H.; Wang, Y.; Hou, Y.; Dong, Z.; Zhang, L. Mechanical properties and microstructural characteristics of 316L stainless steel fabricated by laser powder bed fusion and binder jetting. J. Mater. Res. Technol. 2023, 24, 4427–4439. [Google Scholar] [CrossRef]
  11. Alegre, J.M.; Díaz, A.; García, R.; Peral, L.B.; Lorenzo-Bañuelos, M.; Cuesta, I.I. Mechanical and Fatigue Properties of Ti-6Al-4V Alloy Fabricated Using Binder Jetting Process and Subjected to Hot Isostatic Pressing. Materials 2024, 17, 3825. [Google Scholar] [CrossRef]
  12. Meenashisundaram, G.K.; Xu, Z.; Nai, M.L.S.; Lu, S.; Ten, J.S.; Wei, J. Binder jetting additive manufacturing of high porosity 316L stainless steel metal foams. Materials 2020, 13, 3744. [Google Scholar] [CrossRef]
  13. Padmakumar, M. Additive Manufacturing of Tungsten Carbide Hardmetal Parts by Selective Laser Melting (SLM), Selective Laser Sintering (SLS) and Binder Jet 3D Printing (BJ3DP) Techniques. Lasers Manuf. Mater. Process. 2020, 7, 338–371. [Google Scholar] [CrossRef]
  14. Mostafaei, A.; Elliott, A.M.; Barnes, J.E.; Li, F.; Tan, W.; Cramer, C.L.; Nandwana, P.; Chmielus, M. Binder jet 3D printing—Process parameters, materials, properties, modeling, and challenges. Prog. Mater. Sci. 2021, 119, 100707. [Google Scholar] [CrossRef]
  15. Fang, X.; Zu, Y.; Ma, Q.; Hu, J. State of the art of metal powder bonded binder jetting printing technology. Discov. Mater. 2023, 3, 15. [Google Scholar] [CrossRef]
  16. Batmaz, R.; Zardoshtian, A.; Sabiston, T.D.; Tangestani, R.; Chakraborty, A.; Krutz, N.; Pendurti, S.; Natarajan, A.; Martin, E. An Investigation into Sinterability Improvements of 316L Binder Jet Printed Parts. Metall. Mater. Trans. A Phys. Metall. Mater. Sci. 2022, 53, 915–926. [Google Scholar] [CrossRef]
  17. Mao, Y.; Li, J.; Li, W.; Cai, D.; Wei, Q. Binder jetting additive manufacturing of 316L stainless-steel green parts with high strength and low binder content: Binder preparation and process optimization. J. Mater. Process. Technol. 2021, 291, 117020. [Google Scholar] [CrossRef]
  18. Jiang, R.; Monteil, L.; Kimes, K.; Mostafaei, A.; Chmielus, M. Influence of powder type and binder saturation on binder jet 3D–printed and sintered Inconel 625 samples. Int. J. Adv. Manuf. Technol. 2021, 116, 3827–3838. [Google Scholar] [CrossRef]
  19. Berger, C.; Pötschke, J.; Scheithauer, U.; Michaelis, A. Influence of Various Binder Jet Printers on the Additive Manufacturing of Hardmetals. Crystals 2024, 14, 947. [Google Scholar] [CrossRef]
  20. Miyanaji, H.; Orth, M.; Akbar, J.M.; Yang, L. Process development for green part printing using binder jetting additive manufacturing. Front. Mech. Eng. 2018, 13, 504–512. [Google Scholar] [CrossRef]
  21. Vukkum, V.B.; Gupta, R.K. Review on corrosion performance of laser powder-bed fusion printed 316L stainless steel: Effect of processing parameters, manufacturing defects, post-processing, feedstock, and microstructure. Mater. Des. 2022, 221, 110874. [Google Scholar] [CrossRef]
  22. Voisin, T.; Shi, R.; Zhu, Y.; Qi, Z.; Wu, M.; Sen-Britain, S.; Zhang, Y.; Qiu, S.R.; Wang, Y.M.; Thomas, S.; et al. Pitting Corrosion in 316L Stainless Steel Fabricated by Laser Powder Bed Fusion Additive Manufacturing: A Review and Perspective. JOM 2022, 74, 1668–1689. [Google Scholar] [CrossRef]
  23. Voisin, T.; Forien, J.-B.; Perron, A.; Aubry, S.; Bertin, N.; Samanta, A.; Baker, A.; Wang, Y.M. New insights on cellular structures strengthening mechanisms and thermal stability of an austenitic stainless steel fabricated by laser powder-bed-fusion. Acta Mater. 2021, 203, 116476. [Google Scholar] [CrossRef]
  24. Melia, M.A.; Duran, J.G.; Koepke, J.R.; Saiz, D.J.; Jared, B.H.; Schindelholz, E.J. How build angle and post-processing impact roughness and corrosion of additively manufactured 316L stainless steel. Npj Mater. Degrad. 2020, 4, 21. [Google Scholar] [CrossRef]
  25. Sander, G.; Babu, A.P.; Gao, X.; Jiang, D.; Birbilis, N. On the effect of build orientation and residual stress on the corrosion of 316L stainless steel prepared by selective laser melting. Corros. Sci. 2021, 179, 109149. [Google Scholar] [CrossRef]
  26. Forcellese, P.; Mancia, T.; Simoncini, M.; Bellezze, T. Investigation on Corrosion Resistance Properties of 17-4 PH Bound Metal Deposition As-Sintered Specimens with Different Build-Up Orientations. Metals 2022, 12, 588. [Google Scholar] [CrossRef]
  27. Forcellese, P.; Mancia, T.; Simoncini, M.; Bellezze, T. Characterization of Microstructure and Localized Corrosion Resistance of Heat-Treated 17-4 PH Stainless Steel Fabricated by Material Extrusion. Metals 2025, 15, 137. [Google Scholar] [CrossRef]
  28. Forcellese, P.; Belegni, S.; Silvi, A.; Mancia, T.; Simoncini, M.; Bellezze, T. Study of corrosion resistance of 17-4 PH stainless steel as-sintered and heat treated samples manufactured by Bound Metal Deposition. La Metall. Ital. 2023, 114, 9–14. [Google Scholar]
  29. Suwanpreecha, C.; Manonukul, A. A Review on Material Extrusion Additive Manufacturing of Metal and How It Compares with Metal Injection Moulding. Metals 2022, 12, 429. [Google Scholar] [CrossRef]
  30. Huang, N.; Cook, O.J.; Argüelles, A.P.; Beese, A.M. Review of Process–Structure–Property Relationships in Metals Fabricated Using Binder Jet Additive Manufacturing. Metallogr. Microstruct. Anal. 2023, 12, 883–905. [Google Scholar] [CrossRef]
  31. Kaae, P.H.; Eikeland, E.Z. Corrosion Performance of Additively Manufactured Stainless Steel by Binder Jetting. IOP Conf. Ser. Mater. Sci. Eng. 2022, 1249, 012051. [Google Scholar] [CrossRef]
  32. Gunarathne, C. Corrosion Evaluation of Metal Binder-Jetted Stainless Steel Parts: Influence of Printing Parameters on Performance. ECS Meet. Abstr. 2024, MA2024-01, 2811. [Google Scholar] [CrossRef]
  33. Atapour, M.; Wang, X.; Persson, M.; Odnevall Wallinder, I.; Hedberg, Y.S. Corrosion of Binder Jetting Additively Manufactured 316L Stainless Steel of Different Surface Finish. J. Electrochem. Soc. 2020, 167, 131503. [Google Scholar] [CrossRef]
  34. Wu, Y.; Blaine, D.; Marx, B.; Schlaefer, C.; German, R.M. Sintering densification and microstructural evolution of injection molding grade 17-4 PH stainless steel powder. Metall. Mater. Trans. A Phys. Metall. Mater. Sci. 2002, 33, 2185–2194. [Google Scholar] [CrossRef]
  35. Huber, D.; Stich, P.; Fischer, A. Heat Treatment of 17–4 PH Stainless Steel Produced by Binder Jet Additive Manufacturing (BJAM) from N2-Atomized Powder. Prog. Addit. Manuf. 2022, 7, 187–199. [Google Scholar] [CrossRef]
  36. Chen, W.; Chen, Z.; Chen, L.; Zhu, D.; Fu, Z. Optimization of Printing Parameters to Achieve High-Density 316L Stainless Steel Manufactured by Binder Jet 3D Printing. J. Mater. Eng. Perform. 2023, 32, 3602–3616. [Google Scholar] [CrossRef]
  37. Singh, G.; Missiaen, J.M.; Bouvard, D.; Chaix, J.M. Additive manufacturing of 17–4 PH steel using metal injection molding feedstock: Analysis of 3D extrusion printing, debinding and sintering. Addit. Manuf. 2021, 47, 102287. [Google Scholar] [CrossRef]
  38. Di Pompeo, V.; Santecchia, E.; Santoni, A.; Sleem, K.; Cabibbo, M.; Spigarelli, S. Microstructure and Defect Analysis of 17-4PH Stainless Steel Fabricated by the Bound Metal Deposition Additive Manufacturing Technology. Crystals 2023, 13, 1312. [Google Scholar] [CrossRef]
  39. Mirzababaei, S.; Paul, B.K.; Pasebani, S. Microstructure-property relationship in binder jet produced and vacuum sintered 316L. Addit. Manuf. 2022, 53, 102720. [Google Scholar] [CrossRef]
  40. Lecis, N.; Mariani, M.; Beltrami, R.; Emanuelli, L.; Casati, R.; Vedani, M.; Molinari, A. Effects of process parameters, debinding and sintering on the microstructure of 316L stainless steel produced by binder jetting. Mater. Sci. Eng. A 2021, 828, 142108. [Google Scholar] [CrossRef]
  41. Kumar, P.; Jayaraj, R.; Suryawanshi, J.; Satwik, U.R.; McKinnell, J.; Ramamurty, U. Fatigue strength of additively manufactured 316L austenitic stainless steel. Acta Mater. 2020, 199, 225–239. [Google Scholar] [CrossRef]
  42. Chen, L.; Chen, W.; Fu, Z.; Ding, G.; Chen, Z.; Zhu, D. Binder Jet 3D Printing of 316L Stainless Steel: Orthogonal Printing and Sintering Process Optimization. Adv. Eng. Mater. 2023, 25, 2200641. [Google Scholar] [CrossRef]
  43. Huber, D.; Vogel, L.; Fischer, A. The effects of sintering temperature and hold time on densification, mechanical properties and microstructural characteristics of binder jet 3D printed 17-4 PH stainless steel. Addit. Manuf. 2021, 46, 102114. [Google Scholar] [CrossRef]
  44. Chen, Z.; Chen, W.; Chen, L.; Zhu, D.; Chen, Q.; Fu, Z. Influence of initial relative densities on the sintering behavior and mechanical behavior of 316 L stainless steel fabricated by binder jet 3D printing. Mater. Today Commun. 2022, 31, 103369. [Google Scholar] [CrossRef]
  45. Banas, J.; Mazurkiewicz, A. The effect of copper on passivity and corrosion behaviour of ferritic and ferritic–austenitic stainless steels. Mater. Sci. Eng. A 2000, 277, 183–191. [Google Scholar] [CrossRef]
  46. Shu, J.; Bi, H.; Li, X.; Xu, Z. The effect of copper and molybdenum on pitting corrosion and stress corrosion cracking behavior of ultra-pure ferritic stainless steels. Corros. Sci. 2012, 57, 89–98. [Google Scholar] [CrossRef]
  47. Li, Z.; Chen, J.; Xue, W.; Yin, C.; Song, J.; Xiao, K. Role of segregation behavior of Cu and Sb in the region of inclusions on initial corrosion. npj Mater. Degrad. 2023, 7, 29. [Google Scholar] [CrossRef]
  48. Hu, S.; Han, E.-H.; Liu, X. Atomic-scale evidence for the intergranular corrosion mechanism induced by co-segregation of low-chromium ferritic stainless steel. Corros. Sci. 2021, 189, 109588. [Google Scholar] [CrossRef]
Metals 15 01082 g001
Figure 1. Schematic representation of the different build-up orientations and directions of the 17-4 PH samples fabricated through MBJ. The samples were fabricated with three different build-up orientations (XZ plane) concerning the build plate: 0° (red sample), 45° (green samples), and 90° (blue samples); and three different build-up directions (XY plane) concerning the printhead direction (black arrows): 0°, 45°, and 90°. Build-up orientations were labeled as A, whereas the directions as B.
Figure 1. Schematic representation of the different build-up orientations and directions of the 17-4 PH samples fabricated through MBJ. The samples were fabricated with three different build-up orientations (XZ plane) concerning the build plate: 0° (red sample), 45° (green samples), and 90° (blue samples); and three different build-up directions (XY plane) concerning the printhead direction (black arrows): 0°, 45°, and 90°. Build-up orientations were labeled as A, whereas the directions as B.
Metals 15 01082 g001
Metals 15 01082 g002
Figure 2. XRD diffractograms of the as-sintered A0B0 sample showing the peaks associated with the BCC phase.
Figure 2. XRD diffractograms of the as-sintered A0B0 sample showing the peaks associated with the BCC phase.
Metals 15 01082 g002
Metals 15 01082 g003
Figure 3. Microstructural characterization through optical microscopy of the A0B0 as-sintered sample etched using Kalling’s (a) and Vilella’s (b) reagents.
Figure 3. Microstructural characterization through optical microscopy of the A0B0 as-sintered sample etched using Kalling’s (a) and Vilella’s (b) reagents.
Metals 15 01082 g003
Metals 15 01082 g004
Figure 4. Microstructural characterization through SEM-EDX of the A0B0 as-sintered sample: backscattered detector (a,b) and elemental map (c) showing chromium (blue), copper (green), and niobium (red).
Figure 4. Microstructural characterization through SEM-EDX of the A0B0 as-sintered sample: backscattered detector (a,b) and elemental map (c) showing chromium (blue), copper (green), and niobium (red).
Metals 15 01082 g004
Metals 15 01082 g005
Figure 5. CPP curves of as-sintered samples with different build-up orientations and directions: A0B0, A45B0, and A90B0 (a); A45B45 and A90B45 (b); A45B90 and A90B90 (c).
Figure 5. CPP curves of as-sintered samples with different build-up orientations and directions: A0B0, A45B0, and A90B0 (a); A45B45 and A90B45 (b); A45B90 and A90B90 (c).
Metals 15 01082 g005
Metals 15 01082 g006
Figure 6. Corrosion current density average values and standard deviations of as-sintered 17-4 PH samples.
Figure 6. Corrosion current density average values and standard deviations of as-sintered 17-4 PH samples.
Metals 15 01082 g006
Metals 15 01082 g007
Figure 7. Optical microscopy images of as-sintered samples after the CPP tests: crevice on A0B0 (a); localized attacks on A45B0 (b), A90B0 (c), and A90B45 (d); printing patterns on A45B90 (e). The red marks, visible in (a,c), were drawn after the electrochemical tests to highlight the edge of the polyimide tape.
Figure 7. Optical microscopy images of as-sintered samples after the CPP tests: crevice on A0B0 (a); localized attacks on A45B0 (b), A90B0 (c), and A90B45 (d); printing patterns on A45B90 (e). The red marks, visible in (a,c), were drawn after the electrochemical tests to highlight the edge of the polyimide tape.
Metals 15 01082 g007
Metals 15 01082 g008
Figure 8. Most representative OCP monitoring curves of the wrought and as-sintered samples: 0–24 h (a–c) and 24–96 h (d–f) of exposure to the neutral sodium chloride electrolyte at 30 °C.
Figure 8. Most representative OCP monitoring curves of the wrought and as-sintered samples: 0–24 h (a–c) and 24–96 h (d–f) of exposure to the neutral sodium chloride electrolyte at 30 °C.
Metals 15 01082 g008
Metals 15 01082 g009
Figure 9. Results of the analysis of the instability of the OCP monitoring between 24 and 96 h of exposure to the neutral sodium chloride environment.
Figure 9. Results of the analysis of the instability of the OCP monitoring between 24 and 96 h of exposure to the neutral sodium chloride environment.
Metals 15 01082 g009
Table 1. Average chemical composition (wt.%) of the as-sintered sample.
Table 1. Average chemical composition (wt.%) of the as-sintered sample.
CrNiCuSiCMnMoFe
16.544.773.350.540.020.460.21Bal.
Table 2. The average chemical composition (wt.%) of the grains shown in Figure 4a analyzed through EDX.
Table 2. The average chemical composition (wt.%) of the grains shown in Figure 4a analyzed through EDX.
CrNiCuNbSiFe
Bright grains
(martensite)		Average15.64.44.00.30.775.0
Std. Dev.0.20.10.10.10.10.1
Dark grains
(ferrite)		Average22.21.90.90.31.073.7
Std. Dev.0.10.10.10.00.00.0
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Forcellese, P.; Khan, W.A.; Mancia, T.; Simoncini, M.; Reiser, M.; Kouřil, M.; Bellezze, T. Corrosion Resistance Properties of As-Sintered 17-4 PH Samples Additive-Manufactured Through Binder Jetting. Metals 2025, 15, 1082. https://doi.org/10.3390/met15101082

AMA Style

Forcellese P, Khan WA, Mancia T, Simoncini M, Reiser M, Kouřil M, Bellezze T. Corrosion Resistance Properties of As-Sintered 17-4 PH Samples Additive-Manufactured Through Binder Jetting. Metals. 2025; 15(10):1082. https://doi.org/10.3390/met15101082

Chicago/Turabian Style

Forcellese, Pietro, Wasiq Ali Khan, Tommaso Mancia, Michela Simoncini, Matěj Reiser, Milan Kouřil, and Tiziano Bellezze. 2025. "Corrosion Resistance Properties of As-Sintered 17-4 PH Samples Additive-Manufactured Through Binder Jetting" Metals 15, no. 10: 1082. https://doi.org/10.3390/met15101082

APA Style

Forcellese, P., Khan, W. A., Mancia, T., Simoncini, M., Reiser, M., Kouřil, M., & Bellezze, T. (2025). Corrosion Resistance Properties of As-Sintered 17-4 PH Samples Additive-Manufactured Through Binder Jetting. Metals, 15(10), 1082. https://doi.org/10.3390/met15101082

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop