In this study, 316L stainless steel powder was used to produce a porous body that could be used in a specific environment. In contrast to the existing method of producing filters using only spherical powders, we attempted to produce filters using plate- and needle-like powders and evaluated their performance. In the powder preparation step, the shape change of the powder was analyzed by changing the size of the stainless-steel balls used for ball milling. Then, the variations in properties of the sintered porous body caused by the ball size were investigated. As the average ball size decreased, the average particle size of the powder decreased. Moreover, the surface area and pore size of the porous body decreased. Additionally, when balls of different sizes were mixed, the porous body showed a mixture of coarse and fine pores.
In the electropolishing process, the polishing quality of the metal surface varies according to the contamination of the electrolyte. In this study, the electrolyte was evaluated according to the usage time, and the effect of each factor on electropolishing was investigated. As the electrolyte is contaminated, the concentration of metal ions in the electrolyte increases and the ion conductivity decreases. In addition, the pH and specific gravity of the electrolyte increase due to the metal sludge formed as the metal ion concentration increases. When the electrolyte usage time was more than 5 days, many scratches remained on the surface of 316L stainless steel, and relatively high surface roughness was measured. The surface roughness improvement rate compared to the initial specimen was 30% for the unused electrolyte, 26% on the 3rd day, 19% on the 5th day, and 17.5% on the 13th day. Since the low current density due to electrolyte contamination causes a decrease in polishing efficiency, initial scratches on the metal surface still exist on the polished surface. Therefore, it is necessary to manage the electrolyte to maintain the quality of electropolishing.
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Through isothermal compression testing at various temperatures and strain rates, the thermal deformation behavior of 316L stainless steel was investigated. Utilizing corrected true stress–strain data, an Arrhenius constitutive model with strain compensation was developed. Electron backscatter diffraction and transmission electron microscopy were employed to study the microstructure of the compressed specimens, revealing substantial impacts of temperature and strain rate. Higher temperatures boosted the transition from low-angle to high-angle grain boundaries (HAGB), while also increasing the volume percentage of dynamic recrystallization (DRX) and grain size. The impacts of Dynamic Grain Growth/Dynamic Abnormal Grain Growth restricted DRX at higher deformation temperatures and lower strain rates, but at lower temperatures, HAGB reduced with increasing strain rate. As a result, the proportion of HAGB and the volume fraction of recrystallization both decreased. The percentage of ∑3 n (1 ≤ n ≤ 3) twin boundaries also rose with temperature and followed a similar pattern to HAGB with strain rate. High temperature and high strain rate were the ideal formation conditions. Discontinuous dynamic recrystallization (DDRX) was the predominant DRX mechanism in the steel during thermal deformation, with continuous dynamic recrystallization (CDRX) acting as an auxiliary mechanism largely occurring in the low-temperature and high-strain-rate processing conditions like 1273–1323 K, 0.1–1 s −1 . Additionally, when the temperature rose, CDRX was suppressed while DDRX was encouraged.
In this work, oxidation properties of austenitic 316L stainless steel powder and sintered porous support were investigated at the temperature range of ~600-750 °C for 100 hours in ambient air. Oxidation kinetics was determined by continuous thermogravimetry and analyzed employing parabolic rate law. It was observed that oxidation leads to the formation of an oxide scale, with substantial oxidation occurring at ≥ 650 °C in the powder. The porous steel support was fabricated by tape casting method with two distinct pore former concentrations. The microstructural features of both the powder and support were investigated by X-ray diffractometry and scanning electron microscopy coupled with energy-dispersive X-ray analysis. The mechanical properties of the metal support were examined before and after oxidation via a microhardness test. The effect of porosity on the resulting properties of the metal support was also highlighted. In summary, 316L stainless steel support suits SOCs applications below 600 °C.
This paper introduces an approach for vacuum brazing of niobium-316L stainless steel transition joints for application in superconducting radiofrequency cavity helium jackets. The study takes advantage of good wettability of Ag-Cu-Pd brazing alloy to suppress brittle Fe-Nb intermetallic formation, hence improve the joints’ mechanical performance. The wettability of Ag-Cu-Pd filler metal on niobium, the interface microstructure and mechanical properties of the transition joints were investigated. Two kinds of Ag-Cu-Pd filler metals had been studied and wet well on the niobium, and the wettability of Ag-31.5Cu-10Pd filler metal on niobium was better than Ag-28Cu-20Pd filler metal. Microstructure characterization demonstrated the absence of brittle intermetallic layers in all of the joint interfaces. Mechanical properties of samples prepared with Ag-31.5Cu-10Pd filler metal were also better than their peers made with Ag-28Cu-20Pd filler metal both room temperature (300 K) and liquid nitrogen temperature (77 K). The transition joints displayed shear strengths of 356-375 MPa at 300 K and 440-457 MPa at 77 K, respectively. After undergoing ten thermal cycles between the room temperature and the liquid nitrogen temperature, the transition joints’ leak rates were all lower than 1.1×10-11mbar·L/s. Therefore, Ag-Cu-Pd filler metal is applicable to high vacuum vessels used at cryogenic temperatures.
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The deformation behaviour of materials at the micro-scale level is different from that at the macro-scale level due to the effect of grain size (GS). The mechanism of the influence on martensitic transformation by GS is still unclear, and there are relatively few studies on the relationship between grain refinement and martensitic transformation, most of which focus on the relationship between the initial GS of the material and martensitic transformation. Therefore, in this study, the interaction between grain refinement and martensitic transformation was investigated using a dislocation density-based multiscale constitutive model that incorporated dislocation sliding, strain-induced martensitic transformation (SIMT) related to grain size, and grain refinement. The proposed model evaluated the GS-dependent deformation behaviour of 316L stainless steel (SS). Subsequently, a genetic algorithm was used to determine the parameters of the established model, and the calculated results were compared with that of the experimental data to verify the accuracy of the model. The developed multiscale constitutive model was implemented in Abaqus user subroutine to further investigate the deformation mechanism and validate its accuracy. The results demonstrated that the GS had a significant effect on the SIMT, with the volume fraction of martensite increasing with a rise in the initial austenite GS. In addition, grain refinement affected SIMT and the growth rate of martensite content decreased with the grain refinement caused by deformation. The formation of martensite led to grain refinement, with the refined grains producing negative feedback on the SIMT, thus inhibiting the occurrence of martensitic transformation. This study revealed the microscopic deformation mechanism of 316L SS and provided a constitutive model for micro-forming.
Cutting tools made of the WC-Co sintered carbides are now very popular and are widely used in machining of materials. However, there are numerous problems in this area which require more research and need to be studied further. This paper presents the results of an experimental study aimed at discovering the impact of the microstructure, particularly of the tool substrate grain size, on the quality of the machined surface, cutting forces and temperature in the cutting zone, as well as the tool life. In addition, the impact of the feed was considered. The machining process involved side milling of a cuboidal block made of the AISI 316L steel which, due to its specific properties, is widely used in many industries. The tools used in the tests had different WC phase grain size: 0.18, 0.28 and 0.31 μm, respectively, and moreover the middle specimen had also a non-homogeneous structure and an increased content of the Co matrix. The tests proved a significant impact of the tool microstructure on the tool life and the roughness parameters Ra and Rz of the machined surface. The impact of the studied factors on the forces and the temperature in the cutting zone was not as strong, because it did not exceed 20%. The value and the novel character of the paper results from the fact that it concerns a specific case: side milling of the 316L steel with the use of the WC-Co sintered carbide tools, and consequently provides a contribution to solve a practical industrial issue.
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Herein, we analyzed the morphology of atmospheric plasma-sprayed (APS) coating on medical 316L stainless steel and its influence on the physical and electrochemical properties of implant application. Five types of coatings were examined: hydroxyapatite (HAp), titanium (Ti), zirconium (Zr), Ti/HAp and Zr/HAp. The base properties of the coatings were analyzed via chemical and phase composition, surface topography, surface wettability and in particular the corrosion resistance in Ringer solution in immersed conditions and potentiodynamic test, and EIS analysis. APS coating of pure HAp on 316L stainless steel showed poor cohesive bonding to the substrate material, whereas the application of Ti and Zr interlayer prior to HAp deposition improved surface morphology and coating properties. The beneficial effect of Ti and Zr interlayer under HAp layer on binding was demonstrated. HAp containing coatings (HAp, Ti/HAp and Zr/HAp) show Ca/P ratio greater than 1.8, which may positively influence the differentiation of osteogenic cells and good adhesion to bones. Among the studied materials, the composite coatings with Zr or Zr/HAp showed favorable physicochemical properties and the highest corrosion resistance in Ringer solution.
Selective Laser Melting (SLM) is a modern manufacturing method with many applications in medicine, aerospace and auto-motive industries. SLM processed materials are characterized by good dimensional accuracy and properties comparable or superior to materials obtained by traditional processing methods. In this paper an SLM process was used to obtain 316L stainless steel parts. This paper presents the microstructure, chemical and phase composition, physicochemical and electrochemical properties of 12 groups of tested samples, differentiated by the SLM processing parameters. Based on the investigation, it can be inferred that the selection of the appropriate SLM parameters is very important to determined final material properties. The samples producedwith the energy density E = 600 J/mm3 were observed to possess optimum properties - a homogeneous structure, density closest to the desired one, good wettability and pitting corrosion resistance.
In this work, the 316L austenitic steel based milled and sintered composites with 0.33 wt% and 1 wt% SiC ultra-fine particles addition have been prepared. The high efficient attrition milling provided an efficient size reduction of the 316L steel grains and homogeneous distribution of the SiC nanoparticles before sintering process. Spark plasma sintering (SPS) was used for compaction of milled powder mixtures. The effect of SiC addition on the milling efficiency and the structure of the composites have been studied. It was found that the amount of ceramic addition did not influence the efficiency of milling process, powder mixtures with flake like grains have been obtained. On the other hand, the intensive milling assured an optimal coverage of 316L stainless steel grains with submicron sized ceramic particles in both cases. The sintered composites showed high densities with the presence of small amount of closed porosities. Structural, mechanical and tribological examinations of 316L/SiC composites have been performed and presented.
The effects of turning 316L steel in a laser assisted machining are presented in this paper. The properties of 316L stainless steel are also shown in this article. In order to show correlation between the technological parameters, microgeometry of cutting tools and geometrical structure of surface, turning of material in grade 316L supported by laser has been executed. In addition, optical examination of cutting inserts has been performed and geometrical measurements of machined surfaces have been taken. The results of researches on the effects of the technological parameters and cutting tool's microgeometry on the geometrical structure of the 316L steel surface after turning in LAM conditions are described.
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Purpose: This research conducted to analyse the effect of shot peening on surface structure, hardness, and resistance to corrosion of AISI 316L. Design/methodology/approach: The shot peening process is carried out on the surface of 316L stainless steel samples with four peening durations, and they are 2, 4, 15, and 30 minutes. Shot ball steel with diameter 0.4 mm for metal shot blasting and model S110 of ISO 11124/3 and SAEJ827, with the chemical composition, are C (0.8-1.2 wt.%), Mn (0.6-1.2 wt.%), Si (min. 0.4 wt.%), S (max. 0.05 wt.%), P (max. 0.05 wt.%), with a hardness of steelball, about 40-50 HRC. The pressure of compressor kept constant at 8 bar with a diameter of the nozzle is 5 mm, and the distance between the nozzle and the sample surface variated by 6 cm and 12 cm for each shooting duration. Findings: The result shows that the shot peening increases the surface hardness of the material, changes the microstructure on the surface layer and increases the resistance to corrosion. Shot peening with 30 minutes of shooting duration and 6 cm of shooting distance can improve the metal surface properties, which has a surface hardness of 772.23 HV and good on corrosion resistance. Research limitations/implications: The results of this experiment show that shot peening distance of 6 cm for 30 minutes achieved the highest surface hardness of AISI 316L. The corrosion rate decline with increasing duration and nearer distance of shooting balls. Practical implications: In the development of the implant material, AISI 316L need to be improved, its material properties, so it can be used safely and compatibly. Shot peening is a cold working process of metal to increase the material properties by shooting the steel ball into the surface of a material. Originality/value: Based on the experimental results it was obtained that variations shot peening distance and shot peening duration can change grain morphologies, subsequently affect hardness and corrosion resistance on AISI 316L.
Wstęp i cel: W artykule dokonano analizy struktury stereometrycznej powierzchni i opisano podjęte próby poprawy jej właściwości dla elementów wykonanych metodą wytwarzania przyrostowego. Materiał i metody: Przebadano strukturę stereometryczną powierzchni elementów wytworzonych poprzez selektywne spiekanie wiązką lasera sproszkowanej stali 316L. Podjęto również próbę poprawy parametrów powierzchni wytworzonych elementów poprzez obróbkę skrawaniem, szlifowanie, nagniatanie ślizgowe i toczne. Wyniki: W wyniku przeprowadzonych badań uzyskano znaczą poprawę parametrów względem powierzchni surowych, uzyskanych bezpośrednio w procesie wytwarzania przyrostowego. Jednocześnie parametry powierzchni uzyskanych konwencjonalnymi metodami nie różniły się w znaczący sposób. Wniosek: Warstwa wierzchnia elementów wykonanych metodą laserowego spiekania proszków metali cechuje się znaczną chropowatością. Dodatkowa obróbka tak wytworzonych detali poprzez zastosowanie konwencjonalnych metod takich jak skrawanie lub nagniatanie pozwala w istotny sposób zmniejszyć chropowatość.
EN
Introduction and aim: The article shows the analyze of the surface texture and describes attempts to improve surface parameters for the components made with the use of additive manufacturing technology. Material and methods: The surface texture of the elements made of powdered 316L stainless steel with the use of direct metal laser sintering technology were studied. Also an attempt was made to improve the parameters of the surface of those elements by machining or grinding and after that by roller or slide burnishing. Results: During the studies a significant improvement was achieved, relative to the surface parameters obtained directly in the DMLS process. Surface parameters obtained by conventional methods did not differ significantly. Conclusion: The outer layer of elements made out of metal powders with the laser sintering technology is characterized by a high roughness. Additional mechanical treatment of these parts with the use of conventional methods like turning or grinding and than roller or slide burnishing can significantly reduce the roughness.
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The complex analysis of the interface behaviour has been performed during constrained compression testing of 316L steel plates as a way towards processing of the multilayered metallic materials. The approach is based on a combination of experiments under appropriate operating conditions and computer modelling based on finite element (FE) methodology for interpretation of the test results. Multilayered metallic structure was successfully obtained using the applied constrained compression testing technique. The specially designed die and compression specimens allowed for joining of the steel plates together even at room temperatures. The performed numerical analysis using the ABAQUS/Standard FE software revealed the strain and stress localisation areas within the multilayered structure among other features that are described in the paper. The results are in agreement with experimental observations.
PL
Przeprowadzono kompleksową analizę ewolucji naprężeń i odkształceń w pobliżu granic rozdziału podczas ograniczonego ściskania płytek ze stali 3I6L w celu opracowania procesów wytwarzania wielowarstwowych materiałów metalicznych, w tym o budowie nanostrukturalnej. Przeprowadzone badania są oparte na połączeniu badań doświadczalnych w odpowiednich warunkach / modelowaniem komputerowym opartym o metodę elementów skończonych (MES) w celu interpretacji wykonywanych prób. Przeprowadzone badania pozwoliły na uzyskanie wielowarstwowej struktury metalicznej obserwowanej w przekroju poprzecznym próbek poddanych ograniczonemu ściskaniu. Specjalnie zaprojektowana matryca oraz próbki do ściskania pozwoliły na połączenie stalowych płytek nawet w temperaturze pokojowej. Przeprowadzona analiza numeryczna z wykorzystaniem oprogramowania ABAQUS/Standard ujawniła obszary lokalizacji naprężeń i odkształceń wewnątrz wielowarstwowej struktury, a także inne elementy, które zostały opisane w pracy. Wyniki analizy numerycznej są zgodne z wynikami badań doświadczalnych.
Stosowanie bezniklowej stali austenitycznej 316L na implanty układu kostno-stawowego wiąże się z wieloma problemami eksploatacyjnymi. Jednym ze sposobów radzenia sobie z tymi ograniczeniami może być opracowanie nowych materiałów, w tym kompozytów, z zastosowaniem metalurgii proszków. W artykule przedstawiono wyniki badań tribologicznych spieków 316L i 316LHAp (hydroksyapatyt, HAp) otrzymanych metodą iskrowego spiekania plazmowego z zastosowaniem różnej temperatury spiekania. Dla stali 316L zwiększenie temperatury spiekania z 1000 do 1100°C skutkowało pogorszeniem odporności na zużycie. Niemniej w porównaniu z litą stalą 316L odporność na zużycie tych materiałów była znacząco większa. Dla kompozytów 316L-HAp zwiększenie temperatury spiekania skutkowało polepszeniem odporności na zużycie. Zużycie kompozytu spiekanego w niższej temperaturze było porównywalne ze zużyciem materiału referencyjnego.
EN
The use of 316L stainless steel in osteoarticular system implants is associated with many operational problems. One of the methods that deal with these restrictions may be the development of new materials, including composites, using powder metallurgy. This paper presents the results obtained during tribological tests of 316L and 316L-HAp sintered materials produced with the use of the spark plasma sintering method applying various sintering temperature. The increase of the sintering temperature from 1000 to 1100°C resulted in the deterioration of the wear resistance of 316L. However, compared to solid 316L, the wear resistance of these materials was several dozen times higher. The increase of the sintering temperature resulted in the improvement of the wear resistance of 316L-HAp. The wear resistance of the composites that had been sintered at lower temperatures was comparable to the reference material.
The effects of sintering condition and powder size on the microstructure of MIMed parts were investigated using water-atomized 316L stainless steel powder. The 316L stainless steel feedstock was injected into micro mold with micro features of various shapes and dimensions. The green parts were debound and pre-sintered at 800°C in hydrogen atmosphere and then sintered at 1300°C and 1350°C in argon atmosphere of 5torr and 760torr, respectively. The oxide particles were formed and distributed homogeneously inside the sample except for the outermost region regardless of sintering condition and powder size. The width of layer without oxide particles are increased with decrease of sintering atmosphere pressure and powder size. The fine oxides act as the obstacle on grain growth and the high sintering temperature causes severe grain growth in micro features due to larger amount of heat gain than that in macro ones.
316L stainless steel is a well-established engineering material and lots of components are fabricated by either ingot metallurgy or powder metallurgy. From the viewpoints of material properties and process versatility, powder metallurgy has been widely applied in industries. Generally, stainless steel powders are prepared by atomization processes and powder characteristics, compaction ability, and sinterability are quite different according to the powder preparation process. In the present study, a nanoparticle dispersed micro-sphere powder is synthesized by pulse wire explosion of 316L stainless steel wire in order to facilitate compaction ability and sintering ability. Nanoparticles which are deposited on the surface of micro-powder are advantageous for a rigid die compaction while spherical micro-powder is not to be compacted. Additionally, double step sintering behavior is observed for the powder in the dilatometry of cylindrical compact body. Earlier shrinkage peak comes from the sintering of nanoparticle and later one results from the micro-powder sintering. Microstructure as well as phase composition of the sintered body is investigated.
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Industrial tomography (XCT) is a nondestructive test method that provides information about spatial distribution of X-ray absorption in the analyzed structures. The aim of this paper was to examine the possibility and accuracy of application of XCT method for discontinuity and porosity detection in parts made of 316L stainless steel powder produced by Selective Laser Melting technology. Analysis conducted on three produced test samples showed that the application of XCT as a method of quality control of specimens produced with an additive manufacturing technology offers a wide range of possibilities to detect porosity within materials. Parameters such as the amount of porosity, pore size and pore shape are presented. Accuracy of XCT method strongly depends on the size of the samples analyzed, but the possibility of obtaining information in 3D nondestructively shows considerable advantages of XCT method over traditional metallographic cross-sectional analysis.
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The effect of Akolidine-10 additions (0.001-0.1%) into deaerated, 5M acetic acid solution on corrosion behaviour of 316L (X2CrNiMo 18-14-3) stainless steel has been investigated in the absence and in presence of NaCl addition. It can be postulated that Akolidine-10 decreases the hydrogen activity on the steel corroding surface. Additions of Akolidine-10 into the test solution is particularly advantageous in passive region because it protects steel surface against local corrosion attack.
PL
Badano wpływ dodatków Akolidyny-10 (0,001-0,1%) do odpowietrzonego roztworu 5M kwasu octowego na zachowanie korozyjne stali kwasoodpornej 316L (X2CrNiMo 18-14-3) w nieobecności - i w obecności dodatków NaCl. Uzyskane wyniki pozwalają przyjąć, że Akolidyna-10 zmniejsza aktywność wodoru na korodującej powierzchni stali. Dodatki Akolidyny-10 do roztworu roboczego są szczególnie korzystne w warunkach pasywacji stali, gdyż chronią jej powierzchnię przed lokalnym atakiem korozyjnym.
In this study, we proposed a new method using the spark plasma sintering technique to bond ceramics to alloys. MoSi2 and 316L stainless steel were chosen as sample materials and can be welded well with graded interlayers. We found that dense uniformed bondings were achieved because of the comparable coefficient of thermal expansion of the interlayers. Furthermore, such a compatibility between the graded interlayers prevented MoSi2 with low toughness from the occurrence of microcracks resulted from the residual stresses formed during cooling of the bondings.
PL
W pracy zaproponowano nowa metodę łączenia ceramiki i stopów metodą spiekania iskrowo plazmowego SPS (spark plasma sintering). MoSi2 i stal nierdzewna 316L zostały wybrane jako przykładowe materiały i moga byc łaczone poprzez gradientowe warstwy pośrednie. Okazało się, że zwarte, jednorodne połączenia zostały uzyskane dzieki porównywalnemu współczynnikowi rozszerzalności cieplnej warstw pośrednich. Ponadto, tego rodzaju zgodnosc pomiedzy warstwami pośrednimi zapobiegła wystapieniu mikropęknięć w MoSi2, który jest materiałem o niskiej twardości, będacych wynikiem naprezen powstałych podczas chłodzenia połączeń.
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