Machine Learning Methods for the Prediction of the Inclusion Content of Clean Steel Fabricated by Electric Arc Furnace and Rolling

Machine Learning classification models have been trained and validated from a dataset (73 features and 13,616 instances) including experimental information of a clean cold forming steel fabricated by electric arc furnace and hot rolling. A classification model was developed to identify inclusion contents above the median. The following algorithms were implemented: Logistic Regression, K-Nearest Neighbors, Decision Tree, Random Forests, AdaBoost, Gradient Boosting, Support Vector Classifier and Artificial Neural Networks. Random Forest displayed the best results overall and was selected for the subsequent analyses. The Permutation Importance method was used to identify the variables that influence the inclusion cleanliness and the impact of these variables was determined by means of Partial Dependence Plots. The influence of the final diameter of the coil has been interpreted considering the changes induced by the process of hot rolling in the distribution of inclusions. Several variables related to the secondary metallurgy and tundish operations have been identified and interpreted in metallurgical terms. In addition, the inspection area during the microscopic examination of the samples also appears to influence the inclusion content. Recommendations have been established for the sampling process and for the manufacturing conditions to optimize the inclusionary cleanliness of the steel.

Content Analysis of Equity, Diversity, and Inclusion in the Recreational Sports Journal, 2005–2019

While its content and editorial decisions are independent of NIRSA, the Recreational Sports Journal is NIRSA’s scholarly communication outlet and supported by the NIRSA Foundation. Both the organization and journal share a common interest in shaping the future of college recreational sports programs. In response to and reflective of growing diversity on college campuses, that future prioritizes equity, diversity, and inclusion. This study sought to determine the extent that equity, diversity, and inclusion content has appeared in the Recreational Sports Journal during the time period of May, 2005–April, 2019. A retrospective content analysis was conducted on 200 research articles from the journal. To date, equity, diversity, and inclusion has not been addressed in a meaningful way, at least in this forum and during this time period. There is an urgent need for researchers to address this void. The journal is encouraged to assert greater influence in shaping this future.

Complex permittivity of FeSiAl/Al2O3 ceramic composite at X-band frequencies

The objective of this paper is to extract and study the complex permittivity of the FeSiAl/Al2O3 ceramic composite at X-band frequencies. We studied by simulation the complex permittivity of four composites with FeSiAl content varying from 0% to 15% by volume in the alumina matrix. The influence of the FeSiAl content on the complex permittivity of the FeSiAl / Al2O3 composite was also studied. The results obtained show on the one hand that the complex permittivity depends on the frequency. Indeed, the values of the real and imaginary parts of the complex permittivity decrease with the increase in frequency over the entire frequency range in the X band. On the other hand, the high FeSiAl content has a significant impact on the values of the real and imaginary parts of complex permittivity. Higher values were obtained for composites with a high inclusion content. In this work, we obtained a good agreement between the simulation results and the published experimental results. These results indicate that the FeSiAl / Al2O3 composite can be used in applications as an electromagnetic wave absorbing material.

Effect of ceramic particles on the dynamic strength, deformation and toughness behavior of 42CrMo4

In this study, the effect of non-metallic inclusions on the material behavior of 42CrMo4 was investigated. By adding aluminum oxide particles to steel powder, different inclusion contents were simulated. The mechanical and fracture toughness properties were measured under dynamic loading. The damage was examined using the acoustic emissions. With an increasing inclusion content, a decreasing strength, deformability and fracture toughness were observed. The distribution of the inclusions along the surfaces of the prior steel particles lead to small distances between inclusions and favors the initiation of cracks at low stress. The early appearance of material damage was proven by acoustic emissions.

Shielding Gas and Inclusion Content Effects on Impact Toughness and Tensile Properties of 410NiMo Steel Welds

The effect of shielding gas on the mechanical and microstructural characteristics of ER410NiMo martensitic stainless steel weldments was investigated. Three weldments with various inclusion contents were manufactured using different shielding gas compositions and welding processes: gas metal arc welding (GMAW) with 100% argon (Ar), GMAW 85% Ar/15% carbon dioxide (CO2), and flux cored arc welding (FCAW) 75% Ar/25% CO2. The inclusions in each weldment were characterized by means of scanning electron microscope observations and energy-dispersive spectroscopy analysis. The weldments underwent postweld heat treatment, after which the chemical composition and reformed austenite proportion were measured to account for microstructural effects. Hardness measurements, tensile tests, and impact toughness tests using the Charpy method were performed. The results showed that the Charpy V-notch (CVN) absorbed energy decreases with increasing inclusion content. The highest CVN absorbed energy, 195 J, was obtained for the GMAW 100% Ar weld, which had the lowest inclusion content. GMAW 85% Ar/15% CO2, with four times more inclusions than the former, had a CVN absorbed energy of 63 J. The current manufacturing process, FCAW 75% Ar/25% CO2, was found to have an inclusion content three times higher than the GMAW 100% Ar weld but a CVN absorbed energy of 66 J, which is close to the GMAW 85% Ar/15% CO2 weld. The results showed that using GMAW 100% Ar as a replacement to FCAW 75% Ar/25 % CO2 would lead to a three-fold improvement in terms of absorbed impact energy. The effect of inclusions on tensile properties, which was not clearly identified as several factors, in addition to inclusion content, affects the weld strength and elongation. Overall, the yield and ultimate tensile strengths differed slightly: 724 and 918 MPa for GMAW 100% Ar, 746 and 927 MPa for GMAW 85% Ar/15% CO2, and 711 and 864 MPa for FCAW 75% Ar/25% CO2, respectively.

Origin of the Inclusions in Production-Scale Electrodes, ESR Ingots, and PESR Ingots in a Martensitic Stainless Steel

The focus of the study was to define the origin of the inclusions in production-scale electro-slag remelting, (ESR) and electro-slag remelting under a protected pressure controlled atmosphere, (PESR), ingots. The inclusion characteristics in production samples were studied using both polished sample surfaces (two-dimensional (2-D) investigations) and inclusions extracted from steel samples by electrolytic extraction (three-dimensional (3-D) investigations) using SEM in combination with EDS. The results were compared to results from previously reported laboratory-, pilot-, and production-scale trials including electrode, remelted, and conventional ingots. The results show that primary, semi-secondary, and secondary inclusions exist in the remelted ingots. The most probable inclusion to survive from the electrode is a MgO-Al2O3 (spinel). It was also found that the ESR/PESR process slag acts in a similar way to a calcium treatment modification of alumina inclusions. On the whole, the most significant finding is that the overall cleanliness of the electrode including the inclusions in the electrode has an influence on the inclusion content of the ESR and PESR ingots.