PH Stainless Steel Research Articles

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

The present work aims to study the effect of printing orientation angle and heat treatment on the mechanical properties and microstructure of 17-4 PH stainless steel 3D-printed parts obtained by the binder jetting process to assess the suitability of the process and material for rapid tooling applications. To this purpose, tensile specimens were printed at different printing orientation angles (0°, 45°, and 90°). Half of the specimens were left in the as-sintered condition after the 3D-printing operation, while the other half of the specimens was subjected to H900 heat treatment. Then, tensile and hardness tests were performed to investigate the macro-mechanical properties as a function of the printing orientation angles and postprocessing thermal treatment. Scanning electron microscopy with energy dispersive X-ray spectroscopy was used to observe the fracture surfaces and microscopical defects on the binder jetting printed parts to evaluate the fracture mechanisms. It was demonstrated that printing orientation angles do not affect the mechanical properties of 3D-printed parts, while a significant improvement in the microstructure and mechanical properties is observed after the H900 heat treatment.

Corrosion behaviour of nitroxy-QPQ additively manufactured 17-4 PH steel on marine and nuclear reactor components

The study investigates the corrosion behavior of untreated and nitroxy QPQ treated 17-4 PH stainless steel under NaCl environments. Potentiodynamic polarization tests reveal that the nitroxy layer forms an oxide coating, leading to a passivation phase with gradually increasing current density. Oxidation at different temperatures shows variation in corrosion potential, with the lowest current density observed at 450 °C, indicating enhanced corrosion resistance. SEM images of untreated steel show severe crevice and pitting corrosion, whereas nitroxy QPQ treated surfaces exhibit reduced corrosion, with minimal disturbance at 450 °C. Elemental analysis confirms the formation of oxides and nitrides, with increased oxygen content in oxide layers and decreased nitrogen content due to the formation of chromium nitrides. The oxide layer, enriched with oxygen, nitrogen, and chromium, acts as a passive film, protecting against corrosion even in NaCl environments. Elemental mapping further illustrates the correlation between oxidation temperature and corrosion resistance, with higher temperatures resulting in reduced corrosion rates. The combined nitriding and oxidation process enhances corrosion resistance by forming a dense and adherent oxide layer, serving as a barrier against corrosive agents.

Thermal fluctuations on the corrosion behaviour of 17-4PH stainless steel alloys fabricated via material extrusion additive manufacturing technique

Herein, the influence of fluctuating thermal conditions on the corrosion behaviour of 17-4PH stainless steel alloys manufactured via fused filament fabrication is reported. The printed samples were sintered and then exposed to different temperature-fluctuating conditions to simulate the application environment of such alloys. The first set of samples (A) was studied as-sintered, the second set of samples (B) was aged at 480°C for 3 h followed by quenching in water, the third set (C) was exposed to conditions of B followed by aging at 360°C for 3 h and quenching in water and the final set of samples (D) was exposed to conditions of C followed by aging at 200°C for 3 h, quenching in water, aging at 400°C for 3 h, and finally quenching in water. The surface roughness evolved with the temperature conditions. The optical microscopy revealed that sample B had a fine and homogenous distribution of precipitates. Sample B had the highest microhardness values followed by C, D, and A in that order. XRD analysis revealed the presence of retained FCC austenitic phases within the microstructure whose peaks became stronger with the increased thermal fluctuations. The potentiodynamic polarisation studies revealed a distinct linear Tafel region on the cathodic region and a dual-slope inflection point on the anodic region of the polarisation curves. Sample D exhibited the highest corrosion rate whereas sample B revealed the lowest. As such, exposing fused filament fabricated 17-4 PH SS to fluctuating temperature conditions leads to degradation of mechanical strength and corrosion resistance.

Evolution of G-Phase and Its Effect on Hardness in 17-4PH Stainless Steel during Aging Process at 400 °C

Evolution of G-Phase and Its Effect on Hardness in 17-4PH Stainless Steel during Aging Process at 400 °C

The evaluation of the aging process in 15-5 PH materials in terms of formability and microstructure

In this study, the effects of aging heat treatment of 15-5 PH stainless steel material on the mechanical properties, microstructure, and formability were investigated. Instead of cooling in air, cooling in the oven spontaneously was applied in the oven for the first time. Experimental studies show that aging heat treatment was applied for H900, H1025, and H1150 conditions at temperatures of 482 °C, 552 °C, and 621 °C, respectively, and 60 min for H900 and 240 min for H1025 and H1150. It has been observed that controlled cooling in the oven increases the mechanical values of the material obtained by cooling in the air by 8%–10%. The microstructures of the conditions after heat treatment were also examined, and it was observed that the cooling aging heat treatment in the oven caused precipitation hardening in the microstructure of the material. In addition, when evaluating the formability of the results using V-bending, it was observed that materials which could not withstand bending beyond 75° in Condition A (Con A), the initial state of the material, were smoothly shaped in all conditions and at all angles as a result of the cooling process in the oven. A decrease in spring-back angles has been detected due to the decrease in mechanical properties caused by increasing aging temperature. The highest spring-back value was also observed on a 75° bending die with 10.948° in the H900 condition which has the highest mechanical properties.

Experimental evaluation of different coated cutting tools effects on machinability in turning of 17-4 PH stainless steel and optimization of the cutting parameters

Generally, coated cutting tools are preferred in machining of stainless steel. Especially, CVD coated cutting tools come to the forefront owing to its multilayer structure in the industry. In this study, the effects of CVD and PVD coated cutting tools on machinability were investigated in dry turning of 17-4 PH stainless steel. The cutting tools have exactly the same tool geometry. Based on the Taguchi L16 experimental design, experiments were performed for each coating type at different cutting speeds, feed rates and cutting depths. The evaluation parameters were selected as cutting force, surface roughness, tool life and chip formation. The effect ratio of input parameters to output parameters was evaluated with ANOVA and optimum cutting parameters were determined for each coating type with regression analysis. As a result of this study, PVD coated cutting tools showed superior performance than CVD coated cutting tools. It can be said that PVD coated cutting tools are a great alternative to CVD coated cutting tools in machining of 17-4 PH stainless steel.

Micro-nanojauges design to monitor surface mechanical state during high temperature oxidation of metals with application to 17-4PH stainless steel

Determination of mechanical state of thermal oxide growing during high temperature oxidation is a challenge. Fabrication of nanogauges for monitoring during high temperature oxidation was presently investigated up to 1000 °C. Several materials were tested in terms of mechanical behaviour and maximum working temperature for gauges used as markers during thermal loading under air. The experimental determination of the optimized gauges material for high temperature oxidation was validated. SiO2 offers particularly interesting features for gauges to determine the mechanical state of metal/oxide system. In this article, a special attention has also been paid to two nano-fabrication processes, as well as their limits. The standard electron beam lithography process is well suited to build gauges for oxidation applications, and can be improved by use of reactive ion etching process. The gauges can eventually reach several micrometers height such that the oxidation layer does not cover the gauges during thermal loading for relevant monitoring at short oxidation times. To illustrate, an application to a 17-4PH stainless steel oxidized at 480 °C is proposed and stress kinetics are deduced and related to an advanced thermomechano-chemical model, as well as identification of the numerical values of different thermomechano-chemical parameters associated to mechanisms of growth or relaxation.

Enhancing corrosion fatigue performance of 17-4 PH stainless steel by simultaneous aging and plasma nitriding

This study investigated the effects of simultaneous aging and low-temperature plasma nitriding on the corrosion fatigue performance of 17-4 PH stainless steel. Plasma nitriding was conducted under two temperatures of 400 and 500 °C and, for comparison, some other specimens were subjected to aging treatment at the same temperatures and times. Microstructural characterization by scanning electron microscope (FESEM) and electron backscatter diffraction (EBSD) confirmed similar structures at the core in the nitrided and aged specimens, thereby, the influence of nitrogen at the surface of 17-4 alloy could be carefully investigated. X-ray diffraction and grazing incidence X-ray diffraction (GIXRD) identified expanded martensite as the matrix within the nitrided layer, accompanied by CrN, Fe3N, and Fe4N phases. X-ray photoelectron spectroscopy (XPS) analysis revealed high nitrogen concentration, in regions very close to the surface, after nitriding at 500 °C. The N1s spectra shifted towards lower binding energies, indicating interaction between nitrogen and the matrix atoms, and the formation of nitrides in the nitrided layer. The nitrided thicknesses experienced close values at 400 °C (10 h) and 500 °C (5 h), provided at 400 °C the layer was mostly a supersaturated solid solution but at 500 °C it was composed of iron nitrides and chromium nitride. High hardness values of above 1600 HV0.1 were obtained after optimum plasma nitriding as the result of combined effects of solution strengthening induced by nitrogen atoms and the presence of dispersed nitride phases. EBSD results indicated residual stress within the nitrided layer, which would affect the corrosion fatigue resistance. Experimental findings demonstrated that both aging and plasma nitriding substantially enhanced the corrosion fatigue resistance of 17-4 PH stainless steel in 3.5 wt% NaCl. Moreover, simultaneous aging and plasma nitriding proved superior behavior in corrosion fatigue, primarily due to delayed crack initiation and improved fatigue resistance, without the risk of overaging which is detrimental to mechanical properties.

3D printed hernia mesh implant: a conformability study

Aim: This study aims to explore the sensing capabilities of polyvinylidene fluoride-hydroxyapatite-chitosan (PVDF-HAP-CS) composite-based hernia mesh implants (of conformal/planar design), followed by in-vitro analysis for better understanding of the bio-stability in the patient’s body. Methods: For analyzing the sensing capabilities, a microstrip patch antenna (MPA)-based implantable sensor [with 17-4 precipitate hardened (PH) stainless steel (SS) (bio-compatible) and Cu alloy (non-biocompatible) materials as conducting plane/patch with PVDF-HAP-CS as dielectric material] has been considered separately in this study. Primarily, in this study, the 3D models of the hernia mesh implant have been designed in the high-frequency structure simulator (HFSS) software, and the sensing behaviour of the same has been recorded. Results: The HFSS results represent that for the 17-4PH SS-based sensor, resonant frequency (fr) decreases from 2.3953 to 2.3800 GHz, whereas the gain increases from 0.54 to 4.02 dB with a SAR value of 1.077 W/kg. The fr for Cu alloy increases up to 30° conformal angle and, after that, starts decreasing, whereas the gain reaches 3.24 dB with a SAR value of 1.238 W/kg. The in-vitro study highlights that both materials (17-4PH SS and Cu alloy) possess a low corrosion rate. Conclusions: The simulation-based comparison of the biosensors with conducting elements 17-4PH SS and Cu alloy for different conformal angles indicates that the 17-4PH SS shows promising results over Cu in terms of higher gain (up to 4.02 dB) and low SAR value (1.077 W/kg) with the fr lying in the industry scientific and medical (ISM) band and therefore may be used for implantable sensor applications and possesses the capability to be used as 3D-printed hernia mesh implant. The in-vitro results with the low corrosion rate ≈ of 5.1 × 10–8 mm/year, 17-4PH SS may be a suitable material for the fabrication of hernia mesh implant.

Iso-Material Manufactured 17-4PH Stainless Steel to Enhance the Nano-indentation, Corrosion, and Cavitation Erosion Behavior

Iso-Material Manufactured 17-4PH Stainless Steel to Enhance the Nano-indentation, Corrosion, and Cavitation Erosion Behavior

Additively manufactured 17–4 PH stainless steels for fracture management devices

ABSTRACT Stainless steel 316L (SS316L) is widely used in fracture management devices. However, SS316L does not offer any bacterial infection resistance and can cause metal-ion sensitivity due to Ni-ions’ presence. 17-4PH can emerge as a promising substitute due to the intrinsic antibacterial properties of copper, a 75% reduction in nickel content, and superior mechanical properties. SS316L and 17–4 PH were manufactured using laser-directed energy deposition (LDED). 17-4PH specimens surpassed the compressive strength of SS316L by over 150%. A static magnetic field was generated in 17–4 PH specimens to understand in vitro bone cell–material interactions. In vitro human fetal osteoblast cell culture and bacterial inhibition study using Staphylococcus aureus and Pseudomonas aeruginosa were carried out on these specimens with SS316L as control and as-processed and magnetised 17–4 PH as treatments. Results demonstrated that magnetised 17–4 PH exhibited 25% enhancement in hFOB proliferation and 70% reduction in bacterial colonisation compared to SS316L.

The Effect of Heat Treatment on the Plasma Nitriding of Hot-rolled 17–7 PH Stainless Steel

17–7 PH stainless steel is a highly versatile material with a multitude of applications in a diverse range of fields, including aerospace, chemistry and petrochemistry, and medicine. The material’s exceptional mechanical properties and corrosion resistance render it the optimal selection for numerous components and instruments. Nevertheless, the surface properties of 17–7 PH stainless steel are inadequate for applications requiring high hardness and wear resistance in certain extreme environments. Due to its excellent mechanical properties and corrosion resistance, it can be utilized in the manufacturing of pharmaceutical equipment components. However, certain specialized environments still require surface nitriding treatment. Considering the complex heat treatment process required for this material, this paper reports a detailed study of the surface performance changes of 17–7 PH steel before and after ion nitriding following aging heat treatment. The study employs rolled 17–7 PH stainless steel as the subject material. The impact of heat treatment on plasma nitriding of stainless steel is investigated by comparing and analyzing the influence of martensite content and dislocation density within the martensite of the material prior to and following heat treatment on the hardness, thickness, and corrosion resistance of the nitrided layer on the surface of the steel after nitriding. The results demonstrate that 17–7 PH stainless steel, which does not undergo heat treatment, exhibits a high internal dislocation density, a high nitriding efficiency, and consequently, a high surface hardness. Following the application of a heat treatment, there is an increase in the martensite content of 17–7 PH stainless steel, a decrease in the dislocation content, and an increase in the matrix hardness.

Expanding the horizons of metal additive manufacturing: A comprehensive multi-objective optimization model incorporating sustainability for SMEs

Metal Additive Manufacturing (MAM) has seen significant growth in recent years, with sub-processes like Metal Material Extrusion (MEX) reaching industrial readiness. MEX, known for its cost-effectiveness and ease of integration, targets a distinct market segment compared to established high-end MAM processes. However, despite technological improvements, its overall integration into the industry as a viable manufacturing technology remains incomplete. This paper investigates the competitiveness of MEX, specifically its integration into the supply chain and the implications on cost and carbon emissions. Utilizing real-world data, the research develops a multi-objective optimization (MOO) model for a four-echelon supply chain including suppliers, airports, production facilities, and customers. The optimization model is combined with a previously developed cost model for MEX to optimize facility location in Norway using the NSGA-II algorithm. Employing a case study approach, the paper examines the production of an industrial part using stainless steel 17-4PH, detailing concrete process costs and system-level costs across four different production scenarios: 10, 100, 1,000, and 10,000 parts. The findings indicate MEX’s potential for cost-effective production at low and diversified volumes, supporting the trend towards customization and manufacturing flexibility. However, the study also identifies significant challenges in maintaining competitiveness at higher production volumes. These challenges underline the necessity for further advancements in MEX technology and process optimization to enhance its applicability and efficiency in larger-scale production settings.

Effect of Heat Treatment on Mechanical Properties of 17-4 PH Stainless Steel Gyroid Lattice Structures Manufactured by Selective Laser Melting and a Study on Weight Reduction Methods

Effect of Heat Treatment on Mechanical Properties of 17-4 PH Stainless Steel Gyroid Lattice Structures Manufactured by Selective Laser Melting and a Study on Weight Reduction Methods

Effects of heat treatment and geometry on mechanical properties and precipitate development in martensitic additively manufactured 17-4 PH

Reliable mechanical properties of precipitation strengthened alloys like 17-4 PH stainless steel are conventionally obtained through tightly controlled thermomechanical processing to optimize the size and distribution of strengthening precipitates. In additive manufacturing, however, the thermal history (e.g. heating and cooling rates) can vary significantly across a part or individual layer causing the precipitate distribution and resulting mechanical properties to be non-uniform. This is especially true for precipitation strengthened alloys like 17-4 PH which require a specific thermal history to achieve the expected phases and properties. To explore this material and the effect that standard heat treatments have on the processing-structure-properties relationship for AM 17-4 PH, a series of thin-wall (0.8 mm) and ASTM E8 size dogbones were printed via SLM and tensile tested in the as-built, solution annealed, and H900 condition. A Vic-2D DIC system was used during tensile testing to obtain full-field strain data. SEM BSE imaging and TEM EDS were used to characterize the larger (60–120 nm) precipitate phases (SiO and NbC) along with the overall microstructure. GISAXS and TEM EDS were used to quantify the size (5–15 nm), shape, distribution, and composition of nanoscale copper-rich precipitates. Overall, the mechanical properties between the E8 and thin-wall samples were similar with yield strengths of 677 and 734 MPa and ultimate strengths of 1049 and 941 MPa in the H900 condition, respectively. The other sample conditions follow similar trends with the only significant difference being a drop in average ductility (0.27 vs 0.17) for the thin-wall geometry. These similarities were hypothesized to stem from several factors which work to lessen the cooling rate dependence of 17-4 PH.

Microstructure and wear property of (TiN + NbC) double ceramic phase-reinforced in FeCrNiCoAl high-entropy alloy coating fabricated by laser cladding

This study delves into the influence of TiN and NbC ceramic particles on the phase structure, grain organization, microhardness, and wear resistance of FeCoNiCrAl High-Entropy Alloy (HEA) composite coatings produced through laser cladding. The integration of ceramic particles induced a dual BCC solid-solution phase structure (B2+BCC), with the formation of a TiNb phase upon the melting and interaction of TiN and NbC in the melt pool. The ceramic particles significantly modified the grain structure of the HEA coatings, disrupting the Columnar-to-Equiaxed Transition (CET) and favoring the emergence of equiaxed grains. The TiN particles induced a substantial refinement of grain size, albeit unevenly, while NbC had a milder effect. The combined presence of TiN and NbC particles resulted in a more uniform grain refinement, enhancing the mechanical properties of the coatings. Notably, the (TiN + NbC)/HEAs composite coating demonstrated superior mechanical performance under the synergistic effect of both ceramic particles. The average microhardness value increased by 55.80 % compared to 17-4Ph stainless steel, and the wear rate was reduced by 88.38 %, with the wear mechanism primarily involving abrasive and oxidative wear.

On 17-4PH stainless steel dental implant for premolar 4 in canine under compressive loading: effect of solid and octet metastructure

On 17-4PH stainless steel dental implant for premolar 4 in canine under compressive loading: effect of solid and octet metastructure

Influence of Thermal Environment Conditions on Mechanical Properties of MEX Printed 17-4 PH Stainless Steel

Influence of Thermal Environment Conditions on Mechanical Properties of MEX Printed 17-4 PH Stainless Steel

Effect of printing process parameters on tensile strength and wear rate of 17-4PH stainless steel deposited using SLM process

Effect of printing process parameters on tensile strength and wear rate of 17-4PH stainless steel deposited using SLM process

Effect of scanning strategy and laser peening on microstructure and fatigue properties of laser-directed energy deposition-built 15-5 PH stainless steel

PurposeThe aim of this paper is to study the effect of laser shock peening (LSP) on mechanical behaviour of the laser-directed energy deposition (LDED)-based printed 15-5 PH stainless steel with U and V notches. The study specifically concentrates on the evaluation of effect of scan strategy, machining and LSP processing on microstructural, texture evolution and fatigue behaviour of LDED-printed 15-5 PH steel.Design/methodology/approachFor LSP treatment, 15-5 PH steel was printed using LDED process with bidirectional scanning strategy (XX [θ = 0°) and XY [θ = 90°]) at optimised laser power of 600 W with a scanning speed of 300 mm/min and a powder feed rate of 3 g/min. Furthermore, LSP treatment was conducted on the V- and U-notched fatigue specimens extracted from LDED-built samples at laser energy of 3.5 J with a pulse width of 10 ns using laser spot diameter of 3 mm. Post to the LSP treatment, the surface roughness, fatigue life assessment and microstructural evolution analysis is performed. For this, different advanced characterisation techniques are used, such as scanning electron microscopy attached with electron backscatter diffraction for microstructure and texture, X-ray diffraction for residual stress (RS) and structure information, Vicker’s hardness tester for microhardness and universal testing machine for low-cycle fatigue.FindingsIt is observed that both scanning strategies during the LDED printing of 15-5 PH steel and laser peening have played significant role in fatigue life. Specimens with the XY printing strategy shows higher fatigue life as compared to XX with both U- and V-notched conditions. Furthermore, machining and LSP treatment led to a significant improvement of fatigue life for both scanning strategies with U and V notches. The extent of increase in fatigue life for both XX and XY scanning strategy with V notch is found to be higher than U notch after LSP treatment, though without LSP samples with U notch have a higher fatigue life. As fabricated sample is found to have the lowest fatigue life as compared to machines and laser peened with both scan strategies.Originality/valueThis study presents an innovative method to improve the fatigue life of 15-5 PH stainless steel by changing the microstructure, texture and RS with the adoption of a suitable scanning strategy, machining and LSP treatment as post-processing. The combination of preferred microstructure and compressive RS in LDED-printed 15-5 PH stainless steel achieved with a synergy between microstructure and RS, which is responsible to improve the fatigue life. This can be adopted for the futuristic application of LDED-printed 15-5 PH stainless steel for different applications in aerospace and other industries.Graphical abstract