Grade Stainless Steel Research Articles

Dry sliding wear Behaviour analysis on treatedAISI 431 stainless steel material by annealing and tempering process

ABSTRACT Stainless steel, a high corrosion resistance, available at low cost in the market. Martensitic stainless steels were preferred in limited applications because of their high hardness and wear resistance. Thereby, these materials are suitable for manufacturing cutting tools and small dies. In order to make use of this material for commercial applications where long life is preferred, the material is subjected to heat treatment process. This results in reduction of hardness and to enhance ductility on the martensitic stainless steel material. Chosen for this research work, AISI 431 grade stainless steel were taken and subjected to vacuum annealing, tempering process. 3 samples were subjected to vacuum annealing for three different temperatures such as 723°C, 800°C, 850°C and were named as VA1, VA2, and VA3 respectively. 3 samples were treated to vacuum tempering for 3 different temperatures such as 200°C, 400°C, 600°C and were named as VTI, VT2, and VT3 respectively. All samples were undergone to wear test with the help of wear test tribometer. Later all the samples were subjected to hardness tests and the microstructures were identified with the help of Scanning Electron Microscope. An untreated sample is kept aside and results were compared with treated samples..

Changes in the microstructure of selected structural alloy steel grades identified after their simulated exposure to fire temperature

Results of research on changes in microstructure of selected steel grades used in construction, observed in cooled state after prior exposure to fire temperature are presented in this paper. The following steel grades have been analyzed in detail: S355J2+N, X20Cr13, X6CrNiTi18–10 and X2CrNiMoN22–5–3. These grades are considered to be representative for classic low alloy structural steel of ferritic-pearlitic structure, and several special grades of stainless steel varying in microstructure: martensitic, austenitic and mixed, austenitic-ferritic of duplex type. Analysis of post-fire susceptibility to initiation and unconstrained propagation of brittle failure was the basic purpose of this research. This property seems to be the key one in the context of potential post-fire continued service of these steels when subjected to load. The presented results seem to correlate well with the results of toughness test conducted on the same steels (presented in [6]). The scenarios of sample heating and long term keeping up in the high temperature, and in particular the temperature levels assumed by the authors have been intentionally selected to enable or exclude the chance of expected structural changes occurring in the material subjected to experiment. The varied effective cooling modes have been designed to simulate the slow cooling in the open air or alternatively, rapid cooling during firefighting action conducted by fire brigade.

PERFORMANCE AND DESIGN OF STAINLESS‐STEEL COMPOSITE STRUCTURES – BEAMS, COLUMNS AND JOINTS

AbstractThe paper summarises a series of investigations conducted in recent years at the University of Sydney on the behaviour and design of stainless steel‐concrete composite structures, with a focus on the mechanical performance of composite beams, columns, and joints. Three stainless steel grades were considered in the experiments, namely austenitic, duplex, and lean duplex. Details of the experiments as well as some of the experimental observations are presented herein, along with the comparison of the test results with the results of simulations. The test results are also compared with the requirements and predictions of international design codes, which are generally developed for carbon steel composite members, in order to investigate their applicability for stainless steel composite members. A number of design recommendations are also developed and presented. The studies are expected to help engineers achieve a deeper understanding of the behaviour and design of stainless steel‐concrete composite members.

Biomimetic calcium phosphate coating on medical grade stainless steel improves surface properties and serves as a drug carrier for orthodontic applications.

Recently, stainless steel (SSL) miniscrew implants have been used in orthodontic clinics as temporary anchorage devices. Although they have excellent physical properties, their biocompatibility is relatively poor. Previously, our group developed a two-phase biomimetic calcium phosphate (BioCaP) coating that can significantly improve the biocompatibility of medical devices. This study aimed to improve the biocompatibility of SSL by coating SSL surface with the BioCaP coating. Titanium (Ti) discs and SSL discs (diameter: 5mm, thickness: 1mm) were used in this study. To form an amorphous layer, the Ti discs were immersed in a biomimetic modified Tyrode solution (BMT) for 24h. The SSL discs were immersed in the same solution for 0h, 12h, 24h, 36h and 48h. To form a crystalline layer, the discs were then immersed in a supersaturated calcium phosphate solution (CPS) for 48h. The surface properties of the BioCaP coatings were analysed. In addition, bovine serum albumin (BSA) was incorporated into the crystalline layer during biomimetic mineralisation as a model protein. The morphology, chemical composition and drug loading capacity of the BioCaP coating on smooth SSL were confirmed. This coating improved roughness and wettability of SSL surface. In vitro, with the extension of BMT coating period, the cell seeding efficiency, cell spreading area and cell proliferation on the BioCaP coating were increased. These in vitro results show that the BioCaP coating can improve surface properties of smooth medical grade SSL and serve as a carrier system for bioactive agents.

Development of an In Situ Micro-Corrosion Cell for the Investigation of Pitting Corrosion on Austenitic and Ferritic Stainless Steels

In order to investigate the electrochemical pitting corrosion in more detail, a micro-corrosion cell was developed, allowing real-time in situ optical observations of steel surfaces in direct correlation with electrochemical measurement results. In this study, the austenitic 1.4301–X5CrNi18-10 and the ferritic 1.4016–X6Cr17 stainless steel grades were examined in electrolytes containing chloride ions. The micro-corrosion cell revealed a stable pitting corrosion of the ferritic 1.4016 and metastable pitting corrosion of the austenitic 1.4301. The pits were characterized by means of scanning electron microscopy (SEM) and atomic force microscopy (AFM) in detail. A clear correlation between current peaks in the current density-potential curve and the growth of many small pits on the test surface was established and was identified as metastable pit growth. In general, the pitting corrosion potential increased as the diameter of the test surface decreased for both stainless steels. In contrast to the complex precipitates of 1.4301, chromium precipitates with a significantly higher amount was detected on the entire surface of the 1.4016. The corrosion initiation was identified at the interface between the precipitates and the base material for both stainless steels. By comparing both materials, the ferritic 1.4016 had a lower pitting corrosion potential than the austenitic 1.4301 under all test conditions.

Influence of Sintering Atmosphere, Temperature and the Solution-Annealing Treatment on the Properties of Precipitation-Hardening Sintered 17-4 PH Stainless Steel.

So far, unlike metal injection molding (MIM), conventional powder metallurgy technology (PM) has not been regarded as a method for producing structural elements from 17-4 PH powders, due to the problems of obtaining almost fully compacted shapes after sintering. Nevertheless, recent research demonstrates that it is possible to manufacture sintered parts with high strength by pressing and sintering. The purpose of the study was to determine the degree of densification of 17-4 PH sintered stainless steel during sintering at different temperatures and atmospheres. As a result of the study, it was pointed out that both the temperature and the sintering atmosphere play an essential role in the process of densification of the studied powders during sintering. The formation of delta ferrite and a more pronounced degree of spheroidization of the pores is activated by a higher sintering temperature. Furthermore, after solution-annealed and age-hardened treatment, sintered 17-4 PH stainless steel exhibits high strength with moderate ductility at a level that is difficult to achieve for other sintered stainless-steel grades, such as austenitic, ferritic and martensitic. In turn, the largest improvement in the pitting corrosion resistance in 0.5 M NaCl solution is reached by sintering at 1340 °C in hydrogen and after solid solution treatment.

Effects of Plasma Nitriding Process on AISI 304 Stainless Steel

AISI 304 stainless steel is a type of austenitic stainless steel that contains a high percentage of chromium and nickel. It is one of the most widely used grades of stainless steel and is commonly used in a variety of applications, including kitchen equipment, food processing equipment, and chemical processing equipment. AISI 304 stainless steel is a versatile and widely used material due to its excellent corrosion resistance, durability, and non-magnetic properties. Low-temperature processes like ion implantation, plasma nitriding can prevent the corrosion resistance of stainless steels by diffusion of plasma into the surface of the material, forming precipitation of Chromium nitride. For this research work, plasma nitriding is carried out on AISI 304 at low-temperatures 550°C for the time duration of 8 hrs, 16 hrs and 32 hrs. The formation of nitrogen-enriched layers with high nitrogen content promoted to increase in surface hardness. Wear test were carried out with pin on disc machine and the samples were undergone with hardness tests. The microstructures of plasma treated samples were compared with untreated microstructures. It was noted that phase change occurred from austenite to expanded austenite forming a hard layer from the surface level improving the wear resistance of the material.

Comparison of crack growth rates of IPE beams made from stainless steel in three-point bending

The main focus of research dealing with a fatigue of steel components is mostly performed by mechanical testing with focus set on small-scale components. On the other hand, from a civil engineering viewpoint, the steel load-bearing structures or their elements have much larger dimension, when comparing them to laboratory specimens. Therefore, the fatigue testing took place on IPE 80 specimens made from two different stainless steels AISI 304 and AISI 316, loaded in three-point bending with data collection of crack mouth opening displacement placed in mid-span using clip-on extensometer. This presented study focuses on the comparison of crack propagation rate in linear region of well-known Paris’ law. For the assessment of material constants from Paris’ equation C and m, two steel grades of stainless steel, AISI 304 and AISI 316 were experimentally obtained. To evaluate the experimental data, a three-dimensional (3D) numerical model, representing IPE 80 geometry, in a finite element method (FEM) software Ansys Mechanical APDL was created. The generated numerical results were used to evaluate stress intensity factor values, which serves as a main input to crack propagation Paris’ law.

Selected aspects of the design of special monolithic carbide milling cutters for austenitic steels

In many machining applications, the appropriate selection of cutting toolsin relation to the type of material being machined, the machining parametersand the required shape and dimensional accuracy is of particular importance.This especially applies to operations requiring the use of specific tools, i.e. toolsthat are not included in the standard offer but are tailor-made according tothe individual needs of the customer. The article focuses on the machiningproblems of selected austenitic grades of stainless steel and the selection oftechnologies (i.e. machining parameters and strategies and tool geometry)concerning the design and use of special monolithic carbide milling cutters.The possibilities of manufacturing elements from austenitic steels with highshape and dimensional accuracy and high surface layer quality are limited.Due to their high ductility, the tendency to create growths on the cutting edgeand the high compression strength coefficient, these materials pose a serioustechnological challenge. The analysis of phenomena presented in the articleforms the basis for developing guidelines for designing the machining processusing special monolithic carbide cutters dedicated for specific applications.

Retraction: Investigation of anticorrosive, antibacterial and in vitro biological properties of a sulphonated poly(etheretherketone)/strontium, cerium co-substituted hydroxyapatite composite coating developed on surface treated surgical grade stainless steel for orthopedic applications.

[This retracts the article DOI: 10.1039/C4RA12207K.].

Analysis of Wear Behaviour on AISI 431 Martensitic Stainless Steel by Vacuum Annealing Process

In the research work, AISI 431 grade stainless steel were chosen to investigate the effects of vacuum annealing processes on reducing hardness and enhancing ductility. Although stainless steel of martensitic type are well known for their high hardness, wear resistance and they have limited applications due to high hardness properties. Chosen for this research work, vacuum annealing were carried out to temperatures of 740°C, 840°C and 940°C. The samples were prepared cylindrically to a dimension of 40 mm length and 10 mm diameter. An untreated material was kept aside for comparison.Vacuum annealing involves heating the material in a controlled environment to eliminate impurities and relieve internal stresses, resulting in reduced hardness and improved ductility. To evaluate the effect of wear on annealed material, a pin-on-disc wear test apparatus were used. The wear behavior of the annealed specimens were compared to the untreated material. It includes both the treated and untreated samples, were examined by using a scanning electron microscope (SEM) to obtain images of microstructure. The results of this research work contribute to the understanding of the annealing effects on martensitic stainless steels and provide insights into optimizing their properties for specific applications.

Stress Exposure of Evolved Bacteriophages under Laboratory versus Food Processing Conditions Highlights Challenges in Translatability.

Bacterial viruses, or bacteriophages, are highly potent, target-specific antimicrobials. Bacteriophages can be safely applied along the food production chain to aid control of foodborne pathogens. However, bacteriophages are often sensitive to the environments encountered in food matrices and under processing conditions, thus limiting their applicability. We sought to address this challenge by exposing commercially available Listeria monocytogenes bacteriophage, P100, to three stress conditions: desiccation, elevated temperature, and low pH, to select for stress-resistant bacteriophages. The stressed bacteriophage populations lost up to 5.1 log10 in infectivity; however, the surviving subpopulation retained their stress-resistant phenotype through five passages with a maximum of 2.0 log10 loss in infectivity when exposed to the same stressor. Sequencing identified key mutation regions but did not reveal a clear mechanism of resistance. The stress-selected bacteriophage populations effectively suppressed L. monocytogenes growth at a modest multiplicity of infection of 0.35-0.43, indicating no trade-off in lytic ability in return for improved survivability. The stressed subpopulations were tested for survival on food grade stainless steel, during milk pasteurization, and within acidic beverages. Interestingly, air drying on stainless steel and pasteurization in milk led to significantly less stress and titer loss in bacteriophage compared to similar stress under model lab conditions. This led to a diminished benefit for stress-selection, thus highlighting a major challenge in real-life translatability of bacteriophage adaptational evolution.

Design of stainless steel CHS-concrete infill-carbon steel CHS double-skin stub columns

Concrete filled double-skin tubular (CFDST) stub column with outer stainless steel circular hollow section (CHS) and inner carbon steel CHS is presented in this paper. It combines the strength of stainless steel, concrete and carbon steel, and also provides the stainless steel's durability, ductility and corrosion resistance properties along with the lighter weight due to the sectional feature. Finite element analysis (FEA) is done in this paper and the developed FE models are verified with the available test results on the basis of failure modes, full load-deformation curves and ultimate strengths of the specimens. Afterward, a series of parametric analysis are conducted to investigate the structural performance of each component and the overall column as well as the confining stresses between the tubes and concrete. In addition, the effect of stainless-steel grade, concrete strength, carbon-steel strength, diameter-to-thickness ratio of outer tube, diameter-to-thickness ratio of inner tube and hollow ratio on confining stress and mechanical property of sandwiched concrete is studied. The constitutive models of sandwiched concrete and outer stainless steel tube under plane stress are proposed. Based on these proposed models, the fiber element model is used to predict the mechanical properties of this composite column and then checked with the finite element modelling (FEM) outputs. Different design methods such as ACI code, European code, continuous strength method (CSM), Han et al. method and Nie et al. method are assessed to evaluate the applicability and accuracy. Finally, a new design method for calculating the ultimate bearing capacity of the CFDST stub column is proposed, which exhibits good agreement with the results of the FEA.

Features of the implement of cadmium-based Electroplating coatings

The rapid economic, scientific and technical development of the Republic of Kazakhstan in order to achieve the modern level of technological development requires a wide production of metal products and equipment using technically and economically effective methods. For this purpose, one of the main ways of producing corrosion-resistant and efficient metal products and parts is cadmium plating. Cadmium plating is flexible, easily amenable to rolling, stamping, bending, freshly prepared sheathing is better welded on acid-free fluxes than zinc. A study of the technology of cadmium tape made of stainless steel grade 2X18Н10T. A comparative analysis of the types and composition of cadmium electrolytes was carried out. The factors affecting the quality of the resulting packaging are investigated, the calculation of the observed main indicators of products after electrolysis is carried out. It is established that the quality of the coating undergoes changes depending on the composition of the electrolyte, its temperature and current density. The surfactant contributed to the production of a durable packaging layer with the possibility of increasing potency during use. Including work with such surfactants as dextrin, gelatin, carpentry glue. It was seen that the cadmium-coated tape has no gloss unless a surfactant is used. It was found that when the current is overvoltage, the tape is covered with fine-grained granules and darkens. When the tape was cadmated, the cadmium layer deposited on the surface of the tape increased with increasing time.

Duplex Stainless Steels for Thermal Energy Storage: Characterization of Oxide Scales Formed in Carbonate Salts at 500 °C

Next generation concentrated solar power (CSP) plants promise a higher operating temperature and better efficiency. However, new issues related to the corrosion against protection of the construction alloys need to be solved. In this work, two different duplex stainless steels grades, namely 2205 (DS2205) and 2507 (DS2507), were evaluated for their compatibility with the eutectic molten salt mixture of Li2CO3-K2CO3-Na2CO3 at 500 °C in air for thermal energy storage applications. Corrosion tests combined with complementary microscopy, microanalysis and mechanical techniques were employed to study the oxide scales formed on the surface of the duplex steels. The corrosion tests evidenced that the attack morphology in both duplex steels was a uniform oxidative process without localized corrosion. DS2507 presented a better corrosion resistance than DS2205, due to the formation of thinner, compact and continuous oxide layers with higher compositional content in Cr, Ni and Mo than DS2205. The oxide scales of DS2507 showed more remarkable mechanical integrity and adhesion to the metallic substrate.

Shear resistance and design of stainless steel plate girders in fire

In this paper, the shear resistance and design of stainless steel plate girders at elevated temperatures are investigated. A broad range of parameters influencing the structural response of stainless steel plate girders in fire are taken into account, considering (i) austenitic and duplex stainless steel grades, (ii) rigid and non-rigid end posts, (iii) different aspect ratios for the unstiffened portions of the plate girders, (iv) various web slendernesses and (v) different elevated temperature levels. The influence of these parameters on the behaviour of stainless steel plate girders at elevated temperatures is considered. Currently, there is an absence of specific design rules on the fire design of stainless steel plate girders in the European structural steel fire design standard EN 1993-1-2. Considering this, an accuracy assessment of the room temperature stainless steel plate girder design recommendations of the European structural stainless steel design standard EN 1993-1-4 applied with the elevated temperature material properties of stainless steel is performed. The results indicate that this approach leads to unsafe and scattered ultimate strength estimations for stainless steel plate girders in fire. New fire design recommendations for stainless steel plate girders that are in accordance with the existing design provisions of EN 1993-1-2 and EN 1993-1-4 are proposed. The accuracy and safety of the proposed new design recommendations are comprehensively verified against the results from nonlinear finite element modelling.

Dissimilar welding of super duplex stainless steel (SDSS) and pipeline steel – A brief overview

There are different grades of stainless steels available in the market for its better corrosion resistance but super duplex stainless steel find their name due to the presence of two phase microstructure. Due to the complex metallurgical behavior the welding of super duplex stainless steel is quite difficult as compared to the normal grades of the stainless steel. Austenite and ferrite are the two main phases present in super duplex SS almost in equal proportions. To provide better strength, corrosion resistance and sulfide stress cracking than the normal stainless steels, these super duplex SS (SDSS) are specially designed to meet the requirements of structural and pressure vessel applications. This paper basically study about the dissimilar welding challenges during welding of various grades of super duplex stainless steels. Different secondary phases has been formed in the microstructure of duplex stainless steels (DSSs) when these steels are exposed to higher temperatures. These secondary phases degrade their performance at excessive higher temperatures. To minimize the degradation of the engineering performance of DSSs at higher temperatures various types of isothermal treatments have been used.

PLC Based Prepaid Purified Water Drinking Station

PLC based prepaid purified drinking water station was designed and developed to address the safe distribution of purified drinking water at a reasonable cost to the end users and helped reduce the increasing number of solid wastes brought by used plastic bottles. The design of the machine was in accordance with the standard specifications of a water dispenser. The machine was fabricated using high grade stainless steel and food grade PVC water pipes. The evaluation of the machine underwent several trials to meet the desired volume of water. Dispensing of 250ml purified water will be attained by inserting the validated peso coin to the coin acceptor. The preset time for every transaction is four seconds.Overall dimensions of the machine are 60x52x16 inches equipped with 4 mini water pumps, a controller and four gooseneck faucets. The performance of the machine satisfies the perception of the evaluators. The design was based on the standards of a water vending machine and the desired volume of water to be dispensed was met.

Concrete based molten salt storage tanks

High-temperature molten salt mixtures such as chloride-based salts have been widely investigated in recent years as alternate thermal energy storage media since they can enable higher temperature power cycles with higher thermodynamic efficiencies in concentrated solar power plants. They can also be used to decarbonize industrial processes requiring high-grade heat for industries located in electrical grids with increasing penetration of intermittent renewable energy. However, molten salts in general, and chloride salts in particular, are highly corrosive towards metals and thus require special stainless steel grades for storage tank construction. These grades, such as nickel-based alloys, can be up to four times more expensive than a regular grade stainless steel. Therefore, the primary cost driver for high-temperature chloride salts is the tank material instead of the salt itself which limits the commissioning of high-temperature thermal energy storage plants. Until now, a low-cost tank material which can effectively overcome the problems associated with molten salts operating above 670 °C has not been reported. In this work, we present low-cost engineered concrete-based thermal energy storage tanks for molten salts capable of operating at high temperatures even in corrosive environments. The engineered concrete composites are developed using commercially available additives and coatings. Tank prototypes, filled with moderate-temperature nitrate salts, are rigorously tested under thermal cycling conditions to demonstrate that the tanks can effectively withstand thermal shocks experienced during daily salt charge/discharge cycles. Moreover, salt diffusion through the porous concrete walls is shown to be suppressed by using external coatings. Finally, the compatibility of engineered composites with high-temperature chloride salts is qualitatively evaluated under a high-flux solar simulator.

The effect of Diamond Like Carbon coating on the Solid Particles Erosion resistance of grade 410 stainless steel

Surface damage by solid particles impacting at high speed is a significant problem for many applications. Hardening and coating are widely adopted to improve surface resistance. The Diamond-Like Carbon (DLC) coating is produced by highly advanced methods that make it one of the hardest coatings with improved bonding to the substrate. In this study, the Solid Particles Erosion (SPE) resistance of the DLC coating deposited by Plasma Assisted Chemical Vapor Deposition (PACVD) on hardened stainless steel grade 410 (SS 410H) was investigated. The results were compared to the SS 410H and SS 410 without hardening. The ASTM G 76 gas blast tester was used to find the SPE resistance, represented by Erosion Rate (ER), under velocities of (30, 50, 70) meter per second and angles of (30, 45, 60, 70, 90) degrees. The results were used to provide the constants needed for a modified Sheldon-Kanher (SK) ER model to estimate the ER at any velocity and impact angle for the tested materials, most importantly, for the DLC coating. A ductile erosion behavior was observed for the tested materials where the ER is reduced by increasing the impact angle which proves that the DLC coating does not behave as a brittle material under SPE. The DLC coating showed the highest SPE resistance with improvement of 42–65% with almost no significant effect of the velocity and impact angle on the improvement rate. While the SS 410H showed an improvement of 6–44% with a significant fluctuation with the variation of velocities and angles. This study highlights the potential usage of DLC coating in mechanical parts exposed to solid particles, such as turbine/compressor blades.