Explore the vast range of titles available.

17–4 PH martensitic stainless steel foams are frequently used in surgery and dental tools. Porous morphology may increase the usage fields of these foams for biomedical aims. In this work, highly porous 17–4 PH martensitic stainless steel foams were produced with the space holder technique and coated with α-Al 2 O 3 to improve chemical stability and surface properties. Mixing stainless steel, boron powders, and urea with polyvinyl alcohol, pressing the mixture at 180 MPa, removing the urea by dissolving it in water at room temperature, and then removing the binder in the raw pellets through sintering were sequentially performed to prepare the foams. Afterwards, the foams were dip-coated in sol–gel derived AlOOH gel for 7–14-21 days and, finally, heat-treated at 1260 °C to transform AlOOH into α-Al 2 O 3 . The physical, microstructural, and electrochemical properties of the foams were characterized. The metal ion release from the samples decreased thanks to the α-Al 2 O 3 layer. Graphical abstract

In the present work, the effect of quenching and tempering processes on the sharpness performance of 6Cr13 high-carbon martensitic stainless steel knives was investigated. The results show that the sharp persistence of the knife increases as the quenching temperature increases from 975 to 1125 °C. The initial sharpness first increases and then decreases, reaching a maximum of 95.9 mm at 1075 °C. When the tempering temperature is below 300 °C, the initial sharpness and sharp persistence of the knife both decrease with the increase of tempering temperature. The secondary carbide in the steel dissolved and the carbide content decrease continuously with the increase of quenching temperature. After the quenching temperature exceeds 1050 °C, a large amount of secondary carbide solid solution is formed into the austenite. The carbides precipitate from steel matrix after the tempering temperature exceeds 400 °C. The refinement and dissolution of secondary carbides are the main reasons for the good sharpness performance of 6Cr13 steel knives. The variation of hardness has little effect on the sharpness performance. However, the cutting capacity of knives fluctuates more sharply as the hardness decreases. Quenching at 1050–1075 °C and tempering at 180–220 °C can obtain 6Cr13 steel knives with optimal sharpness, hardness and fine grain size combination.

Hydrocarbons, water, carbon dioxide, hydrogen sulfide, chloride, high temperatures and pressures are all involved in the oil and gas production. Thus, corrosion, particularly sulfide stress cracking (SSC), poses a great threat to the integrity of well components such as tubing, casing, packer, and wellhead assembly. Sometimes, SSC can lead to catastrophic failures and must be addressed due to operational security and environmental concerns. Localized corrosion, including SSC can be reduced greatly with the appropriate material selection and optimization of critical operational parameters. The material selection is performed according to service environments vis-a-vis mechanical/ metallurgical attributes of the alloys as prescribed in standards such as API 5CT and ANSI/NACE MR0175/ISO 15156. Currently, corrosion-resistant alloys (CRAs) such as martensitic and duplex stainless steels, nickel, titanium and other precipitation hardened alloys are available and used in oil and gas industries because of their superior mechanical and corrosion properties. Owing to the operating environmental reasons, designer often opt for more expensive CRAs as compared to relatively less expensive materials which fall close to the performance boundary of materials selection criteria, thereby increasing overall cost of crude oil production. Thus, there is a paramount requirement to ascertain the candidate materials appropriately without bearing the cost penalties of over-specifications or the performance shortfalls of under-specified alloys when new fields are discovered. In this paper the application domains of 13Cr martensitic stainless steels are reviewed vis-a-vis limits prescribed in ANSI/NACE MR0175/ISO 15156 standard. The paper will aid in the selection of cost-effective materials for oil and gas production when temperature, pressure, hydrogen sulfide concentration, pH, and salinity vary in different directions and cannot be well defined within standard limits.

CA6NM is a low carbon martensitic stainless steel that is widely applied in hydroelectric turbine manufacturing. Using conventional fusion welding techniques, the fabrication of a thick section in CA6NM requires a V-groove joint design and multiple passes to achieve the required penetration. However, exposure to a substantial heat input through this process renders large fusion and heat-affected zones, microstructural variations, as well as distortion of the assembly, which pose difficulties for the manufacture and performance of the component. The application of a high energy density technique, namely electron beam (EB) welding, was used in the present work to penetrate a 60-mm-thick section in CA6NM with a single pass without filler metal. To prevent cracking in the weldment, the CA6NM was heated to 100–170 °C before EB welding using a zonal preheat treatment, which was applied in situ using a defocused beam. The as-welded CA6NM exhibited a narrow fusion zone (FZ) and a series of distinct yet very small heat-affected zones (HAZ) with different microstructural characteristics. As compared to the base metal (BM) hardness of 289 ± 4 HV, the EB weldment exhibited a hardness maximum of 425 HV in the HAZs and an average hardness of 395 ± 6 HV in the FZ. Post-weld heat treatment (PWHT) was effective in lowering the hardness in the FZ of the EB weldment to a mean value of 346 ± 13 HV.

To improve the strength–toughness of 13Cr4NiMo martensitic stainless steel (13-4MSS), a thermal cyclic heat treatment (TCHT) combined with the advantage of tempering was proposed. The microstructures were characterized by scanning electron microscopy, X-ray diffraction and electron backscattered diffraction, and the mechanical behaviors in terms of tensile properties and impact toughness were analyzed in correlation with microstructural evolution. It was found that grains and the martensitic matrix were refined by TCHT through the cyclic quenching transformation and austenite recrystallization, which was conducive to more nucleation quantity of reversed austenite during tempering. Two-spherical-cap nucleation model was used to explain the effect of refined grains of TCHT on the nucleation of reversed austenite. Grain refinement by TCHT improved the brittle fracture stress to reduce the ductile–brittle transition temperature and thus improved the cryogenic impact toughness of 13-4MSS. Reversed austenite distributed at the martensitic lath boundary enhances the crack arrest performance and increases the brittle fracture stress. It is concluded that reasonable TCHT plus tempering process significantly improves the strength–toughness of 13-4MSS, reflecting the comprehensive effect of grain refinement and reversed austenite.

The influence of chloride ion concentration on the passivation film and corrosion product film of martensitic stainless steels (SS) (13% Cr, modified 13% Cr-1% Mo, modified 13% Cr-2% Mo, and 15% Cr SS) have been investigated using immersion tests and electrochemical measurements in sweet environments at temperatures of 150°C and 180°C in the presence of carbon dioxide (CO2). The corrosion rate of conventional 13% Cr SS was found to increase with increasing chloride ion concentration at 150°C. However, the corrosion rates of modified 13% Cr SS and 15% Cr SS were independent of the chloride ion concentration at 150°C. The corrosion rates of modified 13% Cr SS increased with increasing chloride ion concentration above 1,000 ppm at 180°C. The corrosion rate of 15% Cr SS slightly increased at high chloride ion concentration at 180°C. Chromium-enriched corrosion product films were produced on all alloys considered, except for 15% Cr SS, at 180°C. A passivation film was maintained for 15% Cr SS at 180°C. In addition, the pitting corrosion behaviors were investigated by potentiodynamic polarization curves and open-circuit potential measurements. The behavior of the current density of anodic curves corresponded to the immersion test results. Pitting corrosion on modified 13% Cr-2% Mo SS is considered to repassivate because of low potential compared with pitting potential.

Due to the advantages of relatively low cost, increased energy efficiency, increased deposition rate, and the capacity to create medium to large scale components, wire + arc additive manufacturing (WAAM) has gained growing interest. Super martensitic stainless steel (SMSS) combines outstanding strength, ductility, and corrosion resistance, making it a great option for WAAM. In the present work, an SMSS component was successfully produced by WAAM. Additionally, the influence of post-manufactured heat treatment on the microstructural characteristics and mechanical properties of SMSS components was systematically examined. A microstructural analysis of the as-printed and heat-treated samples revealed the formation of typical martensite and a small amount of retained austenite. However, the sample heat-treated by solutionizing at 1050 °C for 1 h followed by aging at 400 °C for 2 h exhibited a finer martensitic structure with an effective grain size of 5.6 μm compared to as-printed sample, leading to an increase in ultimate tensile strength from 1054 ± 6 MPa to 1141 ± 3 MPa with a concomitant increase in elongation from 7.8 ± 0.4% to 12.6 ± 0.2%. Additionally, the fracture morphology of the solution + aging sample demonstrated a more uniform distribution and greater mean size of dimples, indicating better ductility.

The passivation behaviors of super martensitic stainless steels (SMSS) were studied by polarization curves at passive potential of −0. 1 V and in various NaCl solutions, electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS) analysis. Electrochemical test results showed that, in alkaline solutions, passivation region width was wider, passivation current was smaller, and polarization resistance was greater; thus, the passive film of SMSS in alkaline solutions had better passivation behaviors than that in acidic solutions. The polarization curve and EIS of samples SMSS1 and SMSS2 were also used to study which sample had better passivation behaviors. All results demonstrated that passive film structure of SMSS1 sample was more stable, and capacity of passive film was enhanced. The impact of alloying elements on the passive film (SMSS) passivation capability was also discussed by XPS depth profiling, and XPS depth profiling showed that the composition of the passive film was mainly composed of Fe-oxide and Cr-oxide. So the passive film structures were mixed layers of Fe-oxide and Cr-oxide. Fe oxidation product and Cr oxidation product would help to improve the protective property of passive film, which could promote the formation of a passive film structure more stably and densely.

The Application of stainless steel for electric vehicle (EV) battery housings not only improves the thermal management, but also optimizes crash safety, which also increases the demands for the formability of the stainless steels. The combination of advanced servo screw presses with high motion flexibility and press hardening (PH) enables an enhanced formability and tailored component properties, thereby providing a new possibility for the manufacturing of such complex high-strength parts. Due to the freely programmable and precise motion control of the press ram and cushion, the thermo-mechanical history during the forming process can be adjusted accordingly. In this paper, press hardening with superimposed vibration of ram and cushion, i.e., cushion ram pulsation (CRP), for martensitic stainless steel sheet was investigated. To assess the potential of cushion ram pulsation for the formability and properties improvement, a series of press hardening experiments and FE simulations were carried out with X46Cr13 steel with combination of CRP. By variation of the vibration motion profiles of ram and cushion (superimposed oscillation frequency < 15 Hz), the optimal parameters (press motion profile) for press hardening process were determined considering formability. Finally, the hardness and microstructure of the press hardened part with cushion ram pulsation were evaluated in comparison to the conventional press hardening part.

The aim of this study was to investigate cutting force when milling 40 × 13 stainless steel samples obtained via electron-beam surfacing. The samples were obtained by surfacing the wire made from the martensitic 40 × 13 stainless steel. The microstructure of the samples and the hardness are discussed in the present study. Emphasis is placed on the study of cutting forces when handling the samples. The structure of the samples obtained by electron-beam surfacing consisted of tempered martensite. The average hardness of the samples was similar to the hardness obtained after quenching and tempering the samples—576 HV for horizontally printed workpieces and 525 HV for vertically printed workpieces. High-speed milling, high-efficiency milling, and conventional milling have been proven to be suitable for handling such workpieces. This study shows that an increase in milling width leads to a gradual decrease in specific cutting force. As the milling depth increases, the specific cutting force decreases intensively at first but then more slowly with time. Machining the workpieces made of the martensitic stainless steel and produced by electron-beam surfacing requires the use of purely carbide mills with a diameter of at least 12 mm. Using a high-speed steel as a tool material results in the rapid failure of the tool. The cutting conditions during the investigation allowed for a decrease in the temperature of the cutting edge, cutting force, and the low-rigid end mill bending. Therefore, this study has made it possible to select modes that allow for a reduction in the vibration of the lathe-fixture-tool-part system.