Different Types Of Steel Research Articles

Overview on the management of radioactive waste from fusion facilities: ITER, demonstration machines and power plants

In the absence of official standards and guidelines for nuclear fusion plants, fusion designers adopted, as far as possible, well-established standards for fission-based nuclear power plants (NPPs). This often implies interpretation and/or extrapolation, due to differences in structures, systems and components, materials, safety mitigation systems, risks, etc. This approach could result in the consideration of overconservative measures that might lead to an increase in cost and complexity with limited or negligible improvements. One important topic is the generation of radioactive waste in fusion power plants. Fusion waste is significantly different to fission NPP waste, i.e. the quantity of fusion waste is much larger. However, it mostly comprises low-level waste (LLW) and intermediate level waste (ILW). Notably, the waste does not contain many long-lived isotopes, mainly tritium and other activation isotopes but no-transuranic elements. An important benefit of fusion employing reduced-activation materials is the lower decay heat removal and rapid radioactivity decay overall. The dominant fusion wastes are primarily composed of structural materials, such as different types of steel, including reduced activation ferritic martensitic steels, such as EUROFER97 and F82H, AISI 316L, bainitic, and JK2LB. The relevant long-lived radioisotopes come from alloying elements, such as niobium, molybdenum, nickel, carbon, nitrogen, copper and aluminum and also from uncontrolled impurities (of the same elements, but also, e.g. of potassium and cobalt). After irradiation, these isotopes might preclude disposal in LLW repositories. Fusion power should be able to avoid creating high-level waste, while the volume of fusion ILW and LLW will be significant, both in terms of pure volume and volume per unit of electricity produced. Thus, efforts to recycle and clear are essential to support fusion deployment, reclaim resources (through less ore mining) and minimize the radwaste burden for future generations.

Simulation of the Solidification and Microstructural Evolution in Steel Casting Processes Using the InterDendritic Solidification Tool

InterDendritic Solidification (IDS) is a thermodynamic–kinetic software combined with a microstructure tool developed to simulate the nonequilibrium solidification (non‐EQS) of steels. Herein, its main calculation module, solidification (SOL), is introduced, and some essential results of that module, such as the formation of ferrite and austenite in different types of steels during their solidification, and the formation and dissolution of precipitates during subsequent cooling and heating processes, respectively, following solidification, are presented. The non‐EQS is compared with equilibrium and poor‐kinetics solidification to demonstrate the effect of kinetics on the results using finite solute diffusion and microstructure data. The poor‐kinetics solidification is comparable with the modified Scheil simulation ignoring the solid‐state diffusion of slowly moving metallic elements. A particular emphasis is made on demonstrating how to use a postprocessing treatment to control the residual ferrite amounts in stainless steels and the extent of precipitation in particular steel. In this context, the phenomena occurring behind the results are discussed. Finally, to validate the simulations of the SOL module, its calculations are compared with numerous solidification measurements, such as the liquidus and solidus temperatures of different steels and the residual ferrite amounts in stainless steels.

Friction Stir Welding in Inert Gas Environment (FSW-IG) of AZ31B Magnesium Alloy

Friction stir welding is an area of interest within ISIM Timisoara, several research projects that have addressed this issue being carried out. At ISIM the research started with the approach of FSW welding of some aluminum alloys (as similar and dissimilar materials) and later extended to other types of non-ferrous metallic materials (magnesium, titanium, copper alloys) and different types of steels respectively. New methods / possibilities of application of the FSW welding process were also researched. The paper presents results obtained by ISIM Timisoara within an ongoing national research project regarding the friction stir welding in inert gas environment (FSW-IG) of the AZ31B magnesium alloy. The experimental research aimed to perform a comparative analysis between the FSW-IG welding and the classic FSW welding for AZ31B magnesium alloy, in the same working conditions in terms of welding equipment, welding tools and technological process parameters. The obtained results show that the application of FSW-IG welding compared to the classic FSW welding brings benefits in terms of weld surface appearance, mechanical strength, elongation at break and behavior to the static bending tests.

Design of A Multifunctional Micro-Magnetic Testing Instrument

Micro-magnetic testing technology is capable of non-destructively evaluating the mechanical properties and residual stress in ferromagnetic components. In the applications of micro-magnetic testing technology, several types of magnetic signals, such as magnetic Barkhausen noise, incremental permeability, tangential magnetic field and eddy current, etc., are used to characterize the target properties (mechanical properties and residual stress). In this paper, a unique framework for multifunctional micro-magnetic sensor design is proposed. Accordingly, a multifunctional micro-magnetic instrument is developed. Intermittently superimposed magnetic fields of high (several kHz) and low frequencies (several Hz) are used for material magnetization. Combined magnetic sensors are employed to measure a total of five types of signals, including the magnetic Barkhausen noise, incremental permeability, eddy currents, tangential magnetic field and main flux. Especially, twisted-pair wiring was used for winding two identical sensing coils. One of the sensing coils is used for eddy current or incremental permeability detection and the rest one acts as a compensatory coil to suppress the strong mutual induction voltage in detection coil. The entire instrument is composed of a multi-channel signal generator, a power amplifier, signal processing circuits embedded into the multifunctional sensor and a four-channel signal acquisition device. The multi-channel signal generator is constructed based on FPGA and high speed D/A converters. The direct digital synthesizer and state machine are programed in FPGA to enable the excitation of intermittently superimposed signals of high and low frequencies. Carefully experiments were performed to test the performances of the developed instrument. The results obtained from different types of steels proved that the developed instrument can acquire five types of magnetic signals with high SNR. The features of the five types of magnetic signals can used to distinguish the material and its mechanical properties such as surface hardness.

Literature review of the stress, strain and separating force evaluation during hot bar rolling of different types of steels

Designing new rolling mills, optimization of the number of passes and online control of dimensional accuracy are the processes in which the accurate prediction of roll separating force (RSF) for different types of material is necessary. The formula of RSF is mainly a function of flow stress of the material, strain, strain rate, mean effective pressure and area of contact which further depend on the complexity of deformation and complex diversified boundary conditions in velocity as well as friction. Researchers in the last decades have used finite element analysis (FEA), experimental methods, fluid-like consideration of the material and many more techniques to estimate these parameters for low carbon steel and alloy steel. Based on the reviewed literature, the available formulas are classified into two major categories i.e. (i) Analytical and Empirical solutions and (ii) Finite element-based solutions. The majority of the existing models in the literature rely on empirical adjustments of theories of flat rolling dating back to 1943, whereas FEA-based formulae are only applicable to a single circumstance. In conclusion, it is suggested that it is important to create a fully analytical and relatively simple formula that can more precisely predict the RSF for the bar rolling process.

Properties and performance of steel fiber reinforced concrete beam structure – Review

In present days, different types of steels were used to improve the performance of concrete structures. The steel fibers are used to increase the strength and structural integrity of the concrete beam. The performance of concrete structures was enhanced due to the accumulation of steel fiber reinforced elements. The economical steel fiber reinforced concrete structure was developed with exceptional ultimate strength and shear strength. The dissipation of energy and stress were uniformly distributed along the beam under different cyclic loading. The present topic was used to review the properties and performance on steel fiber reinforced concrete beam structure. The compressive and flexural strength was increased by 20% using steel fiber reinforcement in concrete. The reinforcement mechanism and composition of concrete was the most influential factor on quality and performance of the concrete beam structure.

Corrosion Zones of Rebar in High‐Volume Fly‐Ash Concrete through Potentiodynamic Study in Concrete Powder Solution Extracts: A Sustainable Construction Approach

This research reports the experimental outcomes of potentiodynamic analysis of the steel reinforcement in carbonated and uncarbonated high‐volume fly‐ash concrete powder solution extracts (CPSE). Different percentages of fly‐ash content have been used to form a high‐volume fly‐ash concrete (0%, 20%, 40%, 50%, 60%, and 70%) with three different types of steel reinforced. Three different water‐to‐binder ratios (0.35, 0.40, and 0.45) have been used to form the reinforced concrete. The different zones of corrosion were observed through the anodic polarization curve, which was obtained through the potentiodynamic linear sweep test. It has indeed been demonstrated that concrete with up to 50% fly ash shows better resistance against carbonation, as compared to Ordinary Portland Cement (OPC) concrete. Fully active anodic polarization curve is obtained for carbonated concrete. Corrosion‐resistant steel performed better as compared to TATA TMT and SISCON TMT types of steel. The ANOVA also verifies the experimental observation, which shows that the content of fly ash and types of steel decide the extent of corrosion in the concrete. It has also been observed that the interaction between the fly‐ash content and water‐binder proportion and also the interaction between fly ash and the type of steel show the strong effect on the corrosion activity, which decides the extent of different zones of corrosion.

Progressive Collapse Performance of Steel Beam-to-Column Connections: Critical Review of Experimental Results

Background: The steel beam-to-column connections are vulnerable structural elements when a building loses one or more of its vertical load-carrying components due to abnormal or accidental loading conditions. After a column is destroyed by abnormal loads, the tensile axial force of the beam gradually increased, while the bending moment decreased, and the load-resistance mechanism shifts from a flexural mechanism to a catenary mechanism, with the axial force becoming the prevailing factor. Aims: This paper investigates the progressive collapse performance of steel beam-to-column connections. While undergoing large deformation, the beam-to-column connections are subjected to moment, shear, and tension in conjunction with high ductility demand. Their behavior under monotonic loading depends on the moment-axial tension interaction and greatly affects the progressive collapse resistance of the structure. This paper presents a critical review of experimental tests of different types of steel beam-column joints (flexible, rigid, and semi-rigid) under a central-column-removal scenario. Methods: The experimental results, including load-deformation relationships, failure modes, and catenary effects, are described in detail. The findings are used to evaluate the rotation capacity of different types of steel beam-to-column connections. The results are compared to the acceptance criteria specified by the main progressive collapse guidelines for several beam-to-column connection categories. Results: In simple (flexible) joints, the stiffness and strength at higher drift angles essentially depend on the tensile capacity of the connection that prevents, in some cases, the full development of the catenary mechanism. The connection depth alone does not seem to be an effective parameter to predict the rotational capacity of beam-to-column connections, since different connections with similar values of the connection depth result in very different values of the maximum rotation capacity. In fully rigid and semi-rigid connections, after the column removal, the flexural resistance controls the behavior at the preliminary phase, and the tensile force is almost zero. With increased downward displacement, the axial tensile force also increases, developing a catenary mechanism. Although the stiffness of rigid and semi-rigid connections is higher than flexible connections, both categories result in similar rotation capacity. Conclusion: In all the simple connections herein considered, the plastic rotation capacity obtained by tests was found much higher than the code recommended values that are probably too conservative. On the contrary, for one rigid and two semi-rigid connections, the values of the plastic rotation capacity obtained by tests are lower than the corresponding recommended values. Thus, the suggested acceptance criteria proved to be out of the conservative side.

Quality assessment of AL-C-B coatings on steel surfaces obtained by electro spark alloying

Problem. As a rule, during the operation of the product, the surface layers of materials are most affected. These can be parts that work in aggressive environments, at high temperatures, various force actions, the presence of abrasive particles, etc. Under such conditions, different types of steels and alloys are used, and, most commonly, it is high-alloy, which significantly complicates the manufacturing process and increases the cost of the finished product. Diffusion coating methods are the most widespread in the industry, which is due to the best study and ease of these processes. However, there are alternative methods of surface treatment, which are devoid of the disadvantages of diffusion methods.
 The goal is to develop a method of obtaining boron-containing coatings of the Al-C-B system by the electro spark alloying (ESA), applying STS to the treated surface, to study the processes of structural and phase formation of surface layers depending on the energy processes of ESA and substrate material. Methology. Samples made of steel 20 and 40 were used for the study, on which a coating consisting of their sulfur ointment, aluminum powder, amorphous boron powder was applied. Without waiting for drying, the ESA surfaces of the samples were carried out with a graphite electrode on an installation with a discharge energy of 0.13, 0.55 and 4.9 J. The surface roughness after treatment was determined on a profilograph-profilometer by removing and processing profilograms. Metallographic analysis of coatings was performed using an MIM-7optical microscope, and durometric studies were made on the PMT-3 device according to standard methods. Results: the article presents the original method for obtaining boron-containing coatings of the Al-C-B system by the ESA method, which involves applying a coating consisting of sulfur ointment, aluminum powder, amorphous boron powder on the treated surface, followed by electric spark doping with a graphite electrode.

Mass, Direct Cost and Energy Life-Cycle Cost Optimization of Steel-Concrete Composite Floor Structures

This paper presents a study showing the optimization of the mass, direct (self-manufacturing) costs, and energy life-cycle costs of composite floor structures composed of a reinforced concrete slab and steel I-beams. In a multi-parametric study, mixed-integer non-linear programming (MINLP) optimizations are carried out for different design parameters, such as different loads, spans, concrete and steel classes, welded, IPE and HEA steel profiles, and different energy consumption cases. Different objective functions of the composite structure are defined for optimization, such as mass, direct cost, and energy life-cycle cost objective functions. Moreover, three different energy consumption cases are proposed for the energy life-cycle cost objective: an energy efficient case (50 kWh/m2), an energy inefficient case (100 kWh/m2), and a high energy consumption case (200 kWh/m2). In each optimization, the objective function of the structure is subjected to the design, load, resistance, and deflection (in)equality constraints defined in accordance with Eurocode specifications. The optimal results calculated with different criteria are then compared to obtain competitive composite designs. Comparative diagrams have been developed to determine the competitive spans of composite floor structures with three different types of steel I beam: those made of welded sections and those made of IPE or HEA sections, respectively. The paper also answers the question of how different objective functions affect the amount of the calculated costs and masses of the structures. It has been established that the higher (more wasteful) the energy consumption case is, the lower the obtained masses of the composite floor structures are. In cases with higher energy consumption, the energy life-cycle costs are several times higher than the costs determined in direct cost optimization. At the end of the paper, a recommended optimal design for a composite floor system is presented that has been developed on the multi-parametric energy life-cycle cost optimization, where the energy efficient case is considered. An engineer or researcher can use the recommendations presented here to find a suitable optimal composite structure design for a desired span and uniformly imposed load.

The Influence of Hot-Dip Galvanizing on the Mechanical Properties of High-Strength Steels.

Modern high-strength steels achieve their strength exclusively through the manufacturing process, as the chemical composition of these steels is very similar to the composition of standard-quality steels. Typically, hot-dip galvanizing is used to form a protective zinc layer on the steel parts of structures; nonetheless, the material is exposed to high temperatures during the process. With high-strength steels, this can lead to deterioration of the mechanical properties. This study aims to experimentally examine and evaluate the extent of deterioration of the mechanical properties of high-strength-steel members. The effect was studied on specimens made of three different types of steel with the yield strength ranging from 460 to 1250 MPa. For each type of steel, selected mechanical properties—yield strength, tensile strength, and hardness—were determined on specimens with and without hot-dip galvanization, and the obtained results were mutually compared. Our study shows a significant impact of the hot-dip galvanization process on the mechanical properties of some high-strength steels. With the studied types of steel, the yield strength decreased by up to 18%, the tensile strength by up to 13%, and the hardness by up to 55%.

Friction Stir Processing Influence on Microstructure, Mechanical, and Corrosion Behavior of Steels: A Review.

Friction stir processing (FSP) technology has received reasonable attention in the past two decades to process a wide range of materials such as aluminum, magnesium, titanium, steel, and superalloys. Due to its thermomechanical processing nature, FSP is used to alter grain structure and enhance mechanical and corrosion behavior in a wide range of steels. The refinement in grains and phase transformations achieved in steel after FSP affects hardness, tensile properties, fracture toughness, fatigue crack propagation rate, wear resistance, and corrosion resistance. A number of review papers are available on friction stir welding (FSW) or FSP of nonferrous alloys. In this article, a comprehensive literature review on the FSP/FSW of different types of steels is summarized. Specifically, the influence of friction stir processing parameters such as advancing speed, rotational speed, tool material, etc., on steels’ performance is discussed along with assessment methodologies and recommendations.

Laser Powder Bed Fusion printability of cobalt-free steel powders for manufacturing injection molds

Laser Powder Bed Fusion (LPBF) printing is used for manufacturing conformal cooling injection molds with internal cooling channels. Currently, the steel used to manufacture such molds by LPBF is the maraging 18Ni300. However, this steel is softer at high temperatures and less resistant to corrosion than the reference steel, the AISI H11. Moreover, 18Ni300 contains cobalt, an element that can be harmful to the health of people handling powders made of this steel. In order to find a cobalt-free alternative to 18Ni300, the printability of three different types of steel is studied: maraging stainless steels (CX, L40), martensitic non-stainless steels (42CD4, H11, H13, PM2012) and martensitic stainless steels (X15TN, PM420). The printability of those eight steels is studied through their mechanical properties (Rockwell hardness, Charpy impact test), their internal defects and surface roughness (X-ray tomography), the presence of cracks (optical microscope), and also through their microstructure (X-ray diffraction) in the as-built state. The results show that the stainless steels (PM420, X15TN, L40 and CX) exhibit interesting as-built properties allowing them to be considered as a possible alternative to the maraging steel 18Ni300 to produce LPBFed injection molds. A conformal cooling injection mold was then printed as a demonstrator.

Laser surface hardening of SS316L

Laser surface hardening is one of the effective method to enhance the mechanical properties of localised surface area of engineering parts made of different types of steels and other metals like titanium etc. Laser surface hardening has many advantages over conventional hardening process like, self-quenching, very fast, control over energy input and localised hardening etc. This work presents the effect of different laser parameters on the micro hardness of SS316L after laser hardening. The experimental work was carried out using 30W Diode-pumped nanosecond (ns) pulsed laser. Design of Experiments One Variable at a Time (OVAT) approach was used for experimentation. Laser power, laser scanning speed, frequency and number of passes were the process parameters used for the experiments. Effects of these parameters over the micro hardness of the surface are described. Along with this, discussion of features of microstructures using optical microscope are done. It has been found that, there is around 25% increase in hardness after laser hardening. Hardened depth up to 400 microns was obtained.

Skew Rolling of Bimetallic Rods.

The present article reports selected results of a preliminary study of the process of skew rolling of bimetallic rods. The experiments were conducted using a numerically controlled three-roller skew rolling mill. During the tests, bimetallic rods were rolled from billets whose cores and outer sleeves (bushings) were made of different types of steel. The results demonstrate that the proposed method can be successfully used in the production of bimetallic rods. However, proper fastening of the two materials depends on the geometrical parameters of the billets, and the quality of bimetallic rods depends on the heating method used. When the rods are heated without protective atmospheres, the surface layer of the core gets decarburized and the surfaces of the materials being joined together are oxidized, which hinders the welding process and adversely affects the physical and chemical properties of such products. The results of numerical modeling indicate that the material near the surface tends to flow, which may have a negative impact on the welding process. In addition, the distribution of stress in the tool–workpiece contact zone may make welding of the materials difficult. The results reported in this paper are preliminary and constitute a prelude to a more detailed analysis of bimetallic rod rolling.

Determination of the Optimal Replacement Age for the Preventive Maintenance of Bearing Assemblies Involving Weibull Failure Probability Distribution Functions

This paper describes the determination of optimal replacement age for bearing systems with failure times described by Weibull distributions. Optimal age replacement policies are determined for bearing assemblies produced two different types of steel. The parameters of the Weibull probability distribution functions for the bearings were determined by non-linear least square analysis from published data on rolling contact fatigue lives. The resulting distribution functions are used as inputs into the standard expression for the maintenance cost of an age replacement policy and manipulated symbolically using the computer program Maple. These yields closed form expressions for the policy costs that invariably exhibit the well-known vase shape characteristic of these types of problems. The resulting expressions can then be easily used to determine the optimal replacement age of the bearing components. The problem of determining the optimal age replacement policy of bearing assembles consisting of independent components arranged in series is also examined. The effect on the optimal age replacement time of using the same type steel to manufacture all the components is compared with that of building the bearing assembly using components made with different steels. As expected, the results clearly show the increased superiority of the higher-quality steel components in the form of much longer optimal replacement ages. However, replacement policy efficiencies depend on replacement time in a complex fashion. Moreover, the results also suggest that building bearing assemblies combining high quality and low quality steel components may be wasteful. Overall, computer experimentation and examination of the behavior of cost functions using symbolic manipulation with Maple can produce useful guidelines for the design of optimal age replacement policies.

Structural capacity and fatigue performance of ASTM A709 Grade 50CR steel

ASTM A709 Grade 50CR steel includes a range of 10.5% to 12.5% chromium, which greatly enhances the corrosion resistance of this type of steel in comparison to conventional steels widely used for structural applications. Despite the wealth of information on the durability of ASTM A709 Grade 50CR steel in corrosive environments, there was a gap in the literature concerning how this type of steel responds to the loads that the structures experience during their service life. To investigate this critical aspect and facilitate the future use of corrosion-resistant steel, the current study devised a holistic structural testing program with a focus on bridge applications. For this purpose, a full-scale girder was designed, fabricated, and tested under a four-point bending setup. The girder’s ability to meet the design expectations was assessed by comparing the results to the requirements of AASHTO Bridge Design Specifications. In addition, several tensile and fatigue tests were carried out to obtain an in-depth understanding of the performance of ASTM A709 Grade 50CR steel under both monotonic and cyclic loading scenarios. This led to the development of load–displacement, stress–strain, and S-N curves. The investigations were then expanded to quantify the remaining capacity of three different types of steel, i.e., corrosion-resistant steel, weathering steel, and carbon steel. For this purpose, a set of simulations were performed to estimate the corrosion rate and section loss of the girders under consideration over time. The outcome of this holistic study contributed to providing the insight necessary for the safe and efficient design of structural members made with corrosion-resistant steel.

A macro-pillar compression technique for determining true stress-strain curves of steels

Instrumented indentation testing (IIT) is extensively and successfullyused as an alternative technique for investigations of the mechanical properties of steels, where traditional specimens, such as round bar specimens for tensile tests, are not acquirable. The IIT is based on an assumption that the true stress-strain curve of the analyzed sample follows one of the known constitutive equations, such as the Hollomon, Ludwik, Swift, or other predefined equations. However, steel samples exposed to extreme conditions, such as media with high-temperature or neutron irradiation may exhibit a novel stress-strain relation that follows an unknown constitutive equation. In this situation, the accuracy of the IIT may be doubtful. This article proposes a constitutive model independent technique, called macro-pillar compression testing (MPCT), where constitutive equations are not necessary. The MPCT was conducted on a specimen with pillars and established on the theory of the compression testing. In this study, a modified imaginary radius function was proposed for the pillar to consider its sinking and barreling effect during the compression. Finally, three different types of steel (austenitic stainless, low-alloy and low-carbon steel) were used to verify the accuracy of the MPCT. Both MPCT and round bar tensile tests were performed on each type. The test results show that the true strain-stress curves obtained by MPCT have a good agreement with the corresponding curves by tensile tests.

An Overview of Progressive Collapse Behavior of Steel Beam-to-Column Connections

Local failure of one or more components due to abnormal loading can induce the progressive collapse of a building structure. In this study, by the aid of available full-scale test results on double-span systems subjected to the middle column loss scenario, an extensive parametric study was performed to investigate the effects of different design parameters on progressive collapse performance of beam-to-column connections, i.e., beam span-to-depth ratio, catenary mechanism, and connection robustness. The selected full-scale double-span assemblies consisted of fully rigid (welded flange-welded web, SidePlate), semi-rigid (flush end-plate, extended end-plate), and flexible connections (top and seat angle, web cleat). The test results, including load-deformation responses, development of the catenary mechanism, and connection robustness, are presented in detail. The finding of this research further enables a comprehensive comparison between different types of steel beam-to-column connections since the effects of span-to-depth ratio and beam sections were filtered out.

Numerical Investigation of Composite Shear Walls with Different Types of Steel and Concrete Materials as Boundary Elements

The main purpose of this study is to numerically assess the effect of boundary elements with different types of steel and concrete materials on nonlinear performance of composite steel–reinforced concrete wall (CSRCW) by employing ABAQUS software. Two types of common steel profiles including box and I-shaped sections, located at the middle and extremities of the wall, were used to assess ultimate strength of the CSRCW. In addition, effects of concrete confinement on boundary elements were investigated for fully and partially encasement degrees. Following this, steel materials with three yield stresses of 300, 400 and 500 MPa, and concrete in two grades with compressive strengths of 30 and 40 MPa were considered. The theoretical results demonstrated that numerical models can predict the fracture zones similar to experimental observations where the failure modes of CSRCWs appeared to have ductile mechanisms. Based on the numerical outputs, the presence of I-shaped steel section in the middle of CSRCW participated to effectively distribute the stress throughout the shear wall, which was found to be 6.5% higher than that conventional shear wall. Furthermore, using steel boundary elements with higher yield strengths caused the highest amount of ultimate strength for the CSRCW to be 397.1 kN.