scholarly journals Evolution of Non-Metallic Inclusions in Secondary Steelmaking: Learning from Inclusion Size Distributions

2013 ◽  
Vol 53 (11) ◽  
pp. 1974-1982 ◽  
Author(s):  
Marie-Aline Van Ende ◽  
Muxing Guo ◽  
Enno Zinngrebe ◽  
Bart Blanpain ◽  
In-Ho Jung
Keyword(s):  
Inclusion Size ◽  
Size Distributions ◽  
Metallic Inclusions ◽  
Secondary Steelmaking

The effects of morphology of ferrite and non-metallic inclusions on corrosion behaviour of as-cast 304 stainless steel

CORROSION ◽  
10.5006/3763 ◽  
2021 ◽  
Author(s):  
Danbin Jia ◽  
Liangcai Zhong ◽  
Jingkun Yu ◽  
Zhaoyang Liu ◽  
Yuting Zhou ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Corrosion Behaviour ◽  
Solidification Process ◽  
Inclusion Size ◽  
304 Stainless Steel ◽  
Experimental Conditions ◽  
Quenching Temperature ◽  
Δ Ferrite ◽  
Metallic Inclusions

The effects of morphology of ferrite and non-metallic inclusions on corrosion resistance of as-cast 304 stainless steel (304 SS) were investigated. With the decrease in quenching temperature from 1723 K to 1648 K, the different microstructures of the as-cast 304 SS were obtained as the following series: austenitic-lathy δ ferrite, austenitic-colony δ ferrite and austenitic-blocky δ ferrite, and the average inclusion size increased. The electrochemical results show that the sample with the microstructure of austenitic- lathy δ ferrite and smaller size inclusions had a higher corrosion tendency and the lower pitting resistance. Furthermore, the effect of morphology and content of ferrite on corrosion resistance was greater than that of inclusion size under the current experimental conditions. Therefore, a promising method was developed to improve the corrosion resistance of as-cast 304 SS by changing the solidification process.

scholarly journals Numerical simulation of modification of non-metallic inclusions by calcium treatment in the argon-stirred ladle

2019 ◽  
Vol 116 (5) ◽  
pp. 515
Author(s):  
Edgar Ivan Castro-Cedeno ◽  
Alain Jardy ◽  
Benjamin Boissiere ◽  
Jean Lehmann ◽  
Pascal Gardin ◽  
...  
Keyword(s):  
Flow Model ◽  
Fluid Dynamic ◽  
Steel Ladle ◽  
Local Concentration ◽  
Two Phase ◽  
Euler Flow ◽  
Metallic Inclusions ◽  
Dissolved Species ◽  
Secondary Steelmaking ◽  
Technological Challenge

Nowadays, depending on the steel grade, Ca treatment with the aim of modifying the morphology and melting temperature of non-metallic inclusions is performed in the secondary steelmaking process. The addition of calcium to steel melts rises a technological challenge because at steelmaking temperatures Ca has the tendency to vaporize from the ladle. Efforts are actively pursued in developing solutions that increase Ca yield and improve repeatability of results from treatment to treatment. This work presents a two-phase Euler-Euler flow model of a steel ladle with gas stirring through bottom porous plugs. The model considers that before gas exits through the ladle top, some Ca is transferred from the gas to the liquid steel. The yield is thus defined as the ratio between the Ca transferred to the steel and the total calcium injected into the ladle. The fluid-dynamic calculations are coupled with ArcelorMittal thermodynamic software CEQCSI to get the evolution of the local concentration of dissolved species and non-metallic inclusions assuming local thermodynamic equilibrium. Industrial trials have been performed at one of ArcelorMittal’s facilities with the aim of obtaining data to validate the model. Samples of steel were taken before, during, and after the Ca injection treatment. The total Ca content and the inclusion populations in the steel samples can be compared against the results given by the model, as well as the measured and calculated Ca yield.

Evaluation of Inclusions in P/M Superalloy

2013 ◽  
Vol 747-748 ◽  
pp. 513-517 ◽  
Author(s):  
Hua Yuan ◽  
Zhou Li ◽  
Guo Qing Zhang ◽  
Wen Yong Xu ◽  
Na Liu
Keyword(s):  
Master Alloy ◽  
Inclusion Size ◽  
Metallic Inclusions ◽  
Powder Billet

The non-metallic inclusions in master alloy, P/M superalloy and HIP powder billet were studied in this paper. The results show that the amount of inclusions in master alloy is higher than that of the superalloy powers. The EB-button analysis shows that the main non-metallic inclusions in both the master alloy and the HIP powder billet is Al2O3.The amount of the inclusion in master alloy is about 0.166cm2/kg and the size of most inclusions is in the range of 100μm to 200μm, while the maximum inclusion size reaches 400μm.In the P/M superalloy billet, the content of inclusion is only 0.01cm2/kg and the size of most inclusions is less than 50 μm.

Effect of Non-Metallic Inclusions on Notched Low Cycle Fatigue in P/M IN100 Nickel-Base Superalloy

2007 ◽  
Vol 539-543 ◽  
pp. 2960-2965
Author(s):  
Agnieszka M. Wusatowska-Sarnek ◽  
P. Bhowal ◽  
Daniel Gynther ◽  
Rick Montero
Keyword(s):  
Low Cycle Fatigue ◽  
Notch Root ◽  
Stress Gradient ◽  
Inclusion Size ◽  
Critical Conditions ◽  
Nickel Base Superalloy ◽  
Cycle Fatigue ◽  
Metallic Inclusions ◽  
Nickel Base ◽  
Applied Stresses

The notched low cycle fatigue (LCF) behavior of a P/M (Powder Metallurgy) gas turbine disk superalloy (IN100) was investigated to determine the role of inclusions, such as oxides, that are intrinsic in the process of making powder superalloys. Tests were carried out at temperatures ranging from 426°C to 621°C at several applied stresses. The majority of LCF failures initiated from inclusions (oxides) with minority initiation sites being grain facet in the microstructure. The locations of initiation sites were surface or subsurface, and reduced LCF life was generally associated with surface initiation at the notch root. However, surface initiation was infrequent and observed only at high stresses (i.e., in the presence of large plasticity at the notch root). The stress gradient at the notch root coupled with inclusion size determined the critical conditions for fatigue initiation. In the present paper, these failures and the associated LCF life are discussed in terms of inclusion size and its proximity to the notch root.

scholarly journals Evolution of non-metallic inclusions during heat treatment

2020 ◽  
Vol 117 (4) ◽  
pp. 408
Author(s):  
Chengsong Liu ◽  
Bryan Webler
Keyword(s):  
Heat Treatment ◽  
Size Distribution ◽  
Inclusion Size ◽  
Isothermal Heat Treatment ◽  
Number Density ◽  
Inclusion Composition ◽  
Steel Microstructure ◽  
Metallic Inclusions ◽  
Higher Temperature ◽  
Average Size

Isothermal heat treatment can not only modify steel microstructure, but also non-metallic inclusions. In this work, heat treatment experiments were conducted between 1373 and 1573 K (1100 and 1300 °C) to study the evolution of inclusion composition, morphology, and size distribution. Results showed that during the heat treatment at 1473 and 1573 K (1200 and 1300 °C), two main kinds of inclusions initially in the steel, CaS and MgO–Al2O3–CaO–CaS, gradually transformed to (Ca, Mn)S and MgO–Al2O3–(Ca, Mn)S inclusions, and some MgO–Al2O3–CaO inclusions also transformed to MgO–Al2O3–(Ca, Mn)S. At the lowest temperature studied, 1373 K (1100 °C), little change was observed. No significant changes in number density and area fraction of the measured inclusions were observed, while the average size of inclusions increased after the heat treatment. The extent of transformation of CaS, MgO–Al2O3–CaO–CaS and MgO–Al2O3–CaO inclusions increased with decreasing inclusion size and higher temperature.

scholarly journals Effect of Zr Additions on Non-Metallic Inclusions in X11CrNiMo12 Steel

Metals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1183
Author(s):  
Jaka Burja ◽  
Mitja Koležnik ◽  
Barbara Šetina Batič ◽  
Jožef Medved
Keyword(s):  
Martensitic Steel ◽  
Inclusion Size ◽  
Reaction Products ◽  
Clean Steel ◽  
Metallic Inclusions ◽  
Inclusion Modification ◽  
Steel Cleanliness ◽  
Steel Grades ◽  
Al Additions ◽  
Deoxidation Practice

The production of clean steel is associated with high-quality steel grades for demanding applications. The formation of oxide inclusions mainly depends on the deoxidation practice; it is usually carried out through Al additions, but alumina inclusions can have detrimental effects. An alternative zirconium inclusion modification was used in a creep-resistant steel to improve the cleanliness of laboratory-made steel. The thermodynamics behind the inclusion modification are presented, the reaction products are identified and the steel cleanliness improvement is quantified. The resulting influence of zirconium addition on non-metallic inclusions and mechanical properties is discussed. While the Zr additions drastically reduce the non-metallic inclusion size and area, additions above a certain amount result in the formation of zirconium nitrides that ultimately soften the martensitic steel due to the depletion of nitrogen in solid solution.

scholarly journals An Investigation of Non-Metallic Inclusions in Different Ferroalloys using Electrolytic Extraction

Metals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 687 ◽  
Author(s):  
Yong Wang ◽  
Andrey Karasev ◽  
Pär G. Jönsson
Keyword(s):  
Three Dimensional ◽  
Size Distributions ◽  
Steelmaking Process ◽  
Particle Size Distributions ◽  
Electrolytic Extraction ◽  
Cast Steels ◽  
Metallic Inclusions ◽  
Pure Sio2 ◽  
Pure Al2o3

Ferroalloys are integral constituents of the steelmaking process, since non-metallic inclusions (NMIs) from ferroalloys significantly influence the transformation of inclusions present in liquid steel or they are directly involved in casted steel. In this study, the characteristics of inclusions (such as the number, morphology, size, and composition) in different industrial ferroalloys (FeV, FeMo, FeB, and FeCr) were investigated using the electrolytic extraction (EE) technique. After extraction from the ferroalloy samples and filtration of the solution, the inclusions were investigated on a film filter. The three-dimensional (3D) investigations were conducted using a scanning electron microscopy in combination with energy dispersive spectroscopy (SEM-EDS). The characteristics of inclusions observed in the ferroalloys were compared with previous results and discussed with respect to their possible behaviors in the melt and their effects on the quality of the cast steels. The particle size distributions and floatation distances were plotted for the main inclusion types. The results showed that the most harmful inclusions in the ferroalloys investigated are the following: pure Al2O3 and high Al2O3-containing inclusions in FeV alloys; pure SiO2 and high SiO2-containing inclusions in FeMo alloys; Al2O3 and SiO2-containing inclusions in FeB alloys; and MnO-Cr2O3, Al2O3, and Cr2O3-based inclusions in FeCr alloys.

Micro Behavior Study of Non-Metallic Inclusion in High Strength Shaft Steel

2005 ◽  
Vol 297-300 ◽  
pp. 1229-1234
Author(s):  
Yan Ping Zeng ◽  
Chun Mei Xu ◽  
Jian Xin Dong ◽  
Mai Cang Zhang ◽  
Xi Shan Xie
Keyword(s):  
Rolling Direction ◽  
High Strength ◽  
Inclusion Size ◽  
Tensile Tests ◽  
Metallic Inclusion ◽  
Whole Process ◽  
Behavior Study ◽  
Initiation And Propagation ◽  
Metallic Inclusions ◽  
Average Size

The composition, shape, size and distribution of non-metallic inclusions in a kind of high strength shaft steel enriched CoNi have been investigated. In situ tensile tests in special designed SEM have been conducted to trace the whole process of crack initiation and propagation till to fracture at inclusion. The experimental results show that the non-metallic inclusions in the high strength shaft steel are primarily AlN. Their average size is about 3.6µm. Sometimes, a string of inclusions distributes along the rolling direction. Non-metallic inclusion can induce crack to be initiated by inclusion debonding. When the inclusion size is larger than the critical size, the crack can propagate as the main crack that induces the specimen to fracture.

scholarly journals Correlation of Magnetic Perturbation Inspection Data With Rolling-Element Bearing Fatigue Results

1975 ◽  
Vol 97 (2) ◽  
pp. 151-157 ◽  
Author(s):  
R. J. Parker
Keyword(s):  
Perturbation Technique ◽  
Inclusion Size ◽  
Rolling Element Bearing ◽  
Magnetic Perturbation ◽  
Statistical Life ◽  
Metallic Inclusions ◽  
Deep Groove ◽  
Rolling Element ◽  
Element Bearing ◽  
Inspection Data

A magnetic perturbation technique was used to nondestructively detect subsurface non-metallic inclusions in the inner races of 207-size, deep groove ball bearings. The bearings were fatigue tested at 2750 rpm under a radial load of 5860 newtons (1320 lb). The inner races were subsequently sectioned at fatigue spall locations and at magnetic perturbation signal locations. Analyses of the data indicated good correlation between magnetic perturbation signals and inclusion size and location. Exclusion of those bearings that had significant magnetic perturbation signals did not alter the statistical life of the bearings.

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