Review Of Magnetic Properties And Texture Evolution In Non-Oriented Electrical Steels

Electrical steels can be classified into two groups: grain-oriented (GO) and non-oriented (NGO) electrical steel. NGO electrical steels are mainly considered as core materials for different devices, such as electric motors, generators, and rotating machines. The magnetic properties and texture evolution of NGO electrical steels depend on multiple factors (such as chemical content, heat-treatment, and rolling process) making the development of new products a complex task. In this review, studies on the magnetic properties of NGO electrical steels and the corresponding texture evolution are summarized. The results indicate that further research is required for NGO electrical steels to ensure high permeability and low core loss properties

Effect of Cr and Ni Concentrations on Resilience of Cast Nb-Alloyed Heat Resistant Austenitic Steels at Extreme High Temperatures

Austenitic Cr–Ni Alloyed Heat Resistant Steels with Nb Additions Are Used for Intensively Thermo-Mechanically Loaded Cast Components Working in Extreme High Temperature Oxidizing Environment. their Performance during Static Oxidation and Transient Thermo-Mechanical Loading Was Investigated to Recommend an Optimal Cost-Effective Cr/Ni Composition of Nb-Alloyed Austenitic Class Steels. the Static Oxidation and Transient Thermo-Mechanical Behavior of Three Austenitic Steels with Different Cr/Ni Alloying Levels Were Investigated and Compared for Variety of Working Conditions. Static Oxidation Was Performed between 900 °C and 1000 °C in Air for 400 H. the Critical Temperature Which Increases Spallation during Static Oxidation Was Determined for Each of the Steel Alloying Levels. in Addition, Thermal Cycling of a Constrained Specimen Was Done with Varying Upper Cycling Temperatures between 850 °C and 1000 °C. SEM and TEM Analyses Were Supported by Thermodynamic Simulation of the Phases Precipitated in the Metal Matrix and the Structure of Formed Oxide Layers. These Studies Were Used to Determine the Mechanisms of Degradation of Thermo-Mechanically Loaded Cr/Ni Austenitic Steels at Extreme High Temperatures. a Recommendation for a Cost-Effective Cr/Ni Alloying Level for Different Working Conditions Was Determined

Effect of Annealing Time on Texture Evolution of Fe–3.4 Wt% Si Nonoriented Electrical Steel

Herein, the Effect of Annealing Time on the Texture Evolution in Fe–3.4 Wt.% Si Non-Oriented Electrical Steel is Investigated. Strip Samples Are Cast using a Vacuum Sampling Method, Which Simulate the Solidification Conditions of an Industrial Twin Roll Thin Strip Casting (TRSC) Process. As-Cast Samples with Different Carbon and Sulfur (C&S) Levels Are Hot Rolled (HR) with Varying Levels of Hot Deformation, Cold Rolled (CR) to 0.35 Mm Thickness, and Then Annealed at 1050 °C for Different Holding Times (1, 6, 24 H). to Fe–3.4 Wt.% Si Non oriented Electrical Steel, the Observed Texture Evolution Can Be Divided into Different Stages as Annealing Time is Increased from 1 to 24 H. with Increasing Annealing Time, the Fraction of Goss Texture Decreases Initially and Then Increases Again through the Consumption of Grains with Other Textures. with Additional Time, a Decrease of Pinning Force Due to Precipitate Coarsening Results in Normal Grain Growth, Resulting in an Increase of Grain Size. in This Step, Cube Grains Can Form from Rotated Goss Grains. a Model for Core Loss is Presented and Used to Explain the Core Loss Results

A Modified Johnson-Cook Model Incorporating the Effect of Grain Size on Flow Stress

The mechanical properties of steel are influenced by grain size, which can change through mechanisms such as nucleation and growth at elevated temperatures. However, the classic Johnson-Cook model that is widely used in hot deformation simulations does not consider the effect of grain size on flow stress. In this study, the Johnson-Cook model was modified to incorporate the effects of austenite grain size on flow stress. A finite element model was employed to characterize the effects of grain size on the flow stress for different steel grades over a range of temperatures (900⁰ to 1300⁰). Simulation results show good agreement with experimental observations

Effect of SLM Build Parameters on the Compressive Properties of 304L Stainless Steel

Selective laser melting (SLM) is well suited for the efficient manufacturing of complex structures because of its manufacturing methodology. The optimized process parameters for each alloy has been a cause for debate in recent years. In this study, the hatch angle and build orientation were investigated. 304L stainless steel samples were manufactured using three hatch angles (0◦, 67◦, and 105◦) in three build orientations (x-, y-, and z-direction) and tested in compression. Analysis of variance and Tukey\u27s test were used to evaluate the obtained results. Results showed that the measured compressive yield strength and plastic flow stress varied when the hatch angle and build orientation changed. Samples built in the y-direction exhibited the highest yield strength irrespective of the hatch angle; although, samples manufactured using a hatch angle of 0◦ exhibited the lowest yield strength. Samples manufactured with a hatch angle of 0◦ flowed at the lowest stress at 35% plastic strain. Samples manufactured with hatch angles of 67◦ and 105◦ flowed at statistically the same flow stress at 35% plastic strain. However, samples manufactured with a 67◦ hatch angle deformed non-uniformly. Therefore, it can be concluded that 304L stainless steel parts manufactured using a hatch angle of 105◦ in the y-direction exhibited the best overall compressive behavior

On the Effect of Hot Rolling on Inclusion Size and Distribution in a Cast AISI 1070 Steel Railroad Wheel

The goal of this work is to examine the effect of hot deformation on shrinkage porosity and nonmetallic inclusions in an AISI 1070 grade steel industrially produced wheel casting. Steel cleanliness is an important consideration as it influences the mechanical properties of the final product. A high density of porosity and inclusions have been shown to be detrimental for mechanical properties, especially during hot rolling. Using a laboratory-scale rolling mill, cast preforms were subjected to a 66% cumulative reduction to determine the effect of thermomechanical processing on void closure and inclusions that may produce anisotropy in mechanical properties. Quantitative automated feature analysis, AFA, of inclusion type, size, morphology, and distribution was conducted utilizing an Aspex PICA 1020 scanning electron microscope to determine differences in inclusions and shrinkage porosity in the as-cast and as-rolled conditions. The results were compared with previously reported impact toughness values which indicated a trend with MnS projected length and average impact toughness in the T-L orientation. Reduction in shrinkage porosity was also verified utilizing 3D micro-X-ray CT scans. The AFA results showed a decrease in shrinkage porosity from 177 ppm in the as-cast condition to less than 35 ppm after rolling. Pores were in general much smaller and widely distributed after hot rolling and this would suggest improved impact properties. Analysis of nonmetallic inclusions revealed three primary categories of inclusions that included MnS, Al2O3, and complex inclusions that mainly consisted of MnS with an Al2O3 core, with small quantities of mixed silicates of Mn and Al and calcium aluminates (CaAl2O4)

Residual Stress Distribution, Distortion, And Crack Initiation In Conventional And Intensive Quench Practices

This study evaluates the effect of two different quench practices on distortion, sensitivity to quench cracking, development and distribution of residual stress, microstructural uniformity, and hardenability of standardized test castings. Navy C-rings made of AISI 4340 were quenched in this experiment. Some rings were quenched in a conventional draft tube immersion quench bath, and others were quenched in an intensive quench spray system to compare with the results from the conventional immersion quench bath. The rings were measured with a coordinate measuring machine, for distortion and flatness, before and after quenching. Hardness profiles of the quenched rings showed through hardness of 57.0-59.0 HRC, and the microstructures were largely martensitic. DANTE modeling software was used to predict the quenched properties of the rings, simulating microstructural transformation and residual stresses for each quench practice. XRD was used to measure surface residual stress distribution of the quenched rings, and results were compared to the predicted values by the modeling software. The surface residual stress was tensile for the conventional immersion quench and compressive for the intensive spray quench. Crack initiation correlated to areas of large tensile stress concentration and microstructural heterogeneity

Calibration Of The Johnson–Cook Model At High Temperatures For An Ultra-High Strength CrNiMoV Steel

This paper presents a study on the thermo-mechanical behavior of an ultra-high strength CrNiMoV steel at high temperatures and medium strain rates through hot tensile tests. The material was examined in two conditions: as-cast/heat-treated (AC/HT) and as-rolled (AR). Tensile tests were conducted at temperatures of 800,900,1000,1100, and 1200°C, and strain rates of 0.1,1, and 10s−1. Inclusion and porosity analysis was also performed on the tensile specimens. The results revealed that the flow stress decreased by approximately 70% on average from 800°C to 1200°C, while increasing by approximately 32% on average from 0.1s−1 to 10s−1 in strain rate. The elongation exhibited an increase from 16.5% at 800°C to 33% at 1200°C. However, the ductility transition was slower than expected, particularly for the AC/HT conditions. The AC/HT samples exhibited higher levels of inclusions and porosity compared to the AR samples, with porosity significantly affecting the elongation to failure and ultimate tensile strength (UTS) at a strain rate of 1s−1. Furthermore, calibrated Johnson–Cook parameters were reported and compared, demonstrating excellent agreement between predicted and experimental values with less than 20% variation. The calibrated Johnson–Cook model can be effectively employed for modeling purposes within the studied temperature range, and its application can even be extrapolated for higher strain rates

Failure Analysis of a Pellet-Mill Die

One of the most important parts for pellet-mills is the die, since the die transforms raw materials in small cylinders called pellets. In this paper, a failure analysis was conducted for a pellet-mill die that had not reached its service life expectancy. The failure analysis consist of a characterization of the material using atomic emission spectroscopy, hardness measurements, optical microscopy, scanning electron microscopy (SEM), and energy-dispersive spectroscopy by SEM. Additionally, visual inspection and fractography of the fracture surfaces and FE analysis were performed. It was found that the die material was a CA40 alloy, which microstructure consists of a martensitic matrix with finely dispersed carbides of the type M23C6. Also, a non-common level of inclusion type Al2O3 was found on the microstructure of the die material. According to the fractographic analysis, the crack initiation was located in a high-stress concentration region on the counterbored holes of the die, and also aided by the inclusions on the structure. Crack propagated along the material as an intergranular brittle fracture

Dynamic Characterization of Roma Plastilina No. 1 from Drop Test and Inverse Analysis

Mechanical characterization of soft malleable materials represents a research challenge due to the impossibility to perform standard tests on this type of materials. Diverse characterization procedures are found in the literature for their characterization; however, little advances have been achieved at medium strain rates. This paper presents a characterization method for soft malleable materials to determine the material parameters associated with a given constitutive model. The characterization methodology posed as an inverse problem of Drop Test is formulated and solved as an optimization procedure. The input of the optimization procedure is the experimental measurement from the impact of a steel sphere, of specific diameter, freely released from a specific height on to the soft material. Specifically, the input data consist of the penetration history captured by high speed photography. The output of the procedure is the optimum set of material parameters determined by fitting a numerical simulation to the Drop Test experimental measurements. To evaluate and validate the performance of the proposed characterization method, experiments on Roma Plastilina No. 1 were conducted