Martín Herrera Trejo

Followers

Following

Public Views

eddy alfaro

Silvania Furtado

Universidade Federal do Amazonas

Kyu Hwan Oh

Jyrki Miettinen

Laurens Katgerman

Delft University of Technology

Nawaz Mahomed

SAUD SALEEM

Brian G Thomas

Colorado School of Mines

KENJI CAMEY

Takao Koshikawa

Interests

Uploads

Papers by Martín Herrera Trejo

Effect of solidification path and contraction on the cracking susceptibility of carbon peritectic steels

Metals and Materials International, 2010

$Fig. 5. Evolution of mass fraction of phases as a function of tempera- ture in (a) steel A, (b) steel B and (c) steel C.$

$Fig. 6. Mn microsegregation in the liquid phase as a function of solid fraction evolution for each studied steel. Effect of Solidification Path and Contraction on the Cracking Susceptibility of Carbon Peritectic Steels$

$Fig. 7. Evolution of thermal contraction with respect to solid fraction evolution for each studied steel.$

Download

Evolution of inclusion populations in Al-killed steel during the steelmaking process

Journal of Materials Research and Technology

Characterization of Inclusion Size Distributions in Steel Wire Rods

Materials

The control of inclusions in steel components is essential to guarantee strong performance. The r... more The control of inclusions in steel components is essential to guarantee strong performance. The reliable characterization of inclusion populations is essential not only to evaluate the quality of the components but also to allow the use of analytical procedures for the comparison and discrimination of inclusion populations. In this work, inclusion size distributions in wire rod specimens from six plant-scale heats were measured and analyzed. For the measurements, the metallographic procedure specified in the ASTM E2283 standard was used. The population density function (PDF) approach and the extreme value statistical procedure specified in the ASTM E2283 standard were used to analyze the whole size distribution and the upper tail of the size distribution, respectively. The PDF approach allowed us to identify differences among inclusion size distributions and showed that new inclusions were not formed after the liquid steel treatment process. The extreme value statistical procedure l...

$Figure 2. Evolution of inclusions / mm and area fraction of inclusions.$

Download

Metallurgical Interaction among BNi-9 and Waspaloy, FSX-414 or 304-Type Stainless Steel under TLP Cycle

Metals, 2020

The metallurgical interaction of BNi-9 filler metal paste with Waspaloy, Ni-coated Waspaloy, FSX-... more The metallurgical interaction of BNi-9 filler metal paste with Waspaloy, Ni-coated Waspaloy, FSX-414, and 304-SS is studied in a brazing treatment under an argon atmosphere with an isothermal hold for one hour at 1150 °C. The Waspaloy alloys were brazed under both solubilized and aging conditions. Before brazing, some Waspaloy samples were electrochemically coated with an Ni layer 35-40 μm thick. The microstructures of the FSX-414 and 304-SS alloys showed that the thickness of the isothermal solidification zones was approximately 50 μm, while this thickness was not well defined in the Waspaloy samples. The Ni-coated solubilized Waspaloy showed a wider diffusive zone, which was associated with an increase in the penetration extension of the liquid films. The analysis of grain orientation in all brazed zones of the Waspaloy samples showed aleatory characteristics. Plastic factors in the different brazed zones were also obtained by nanoindentation under 350 mN loads. It was observed th...

Download

Concrete/maghemite nanocomposites as novel adsorbents for arsenic removal

Journal of Molecular Structure, 2018

Concrete/maghemite nanocomposites were prepared by aging a mixture of magnetite nanoparticles (NP... more Concrete/maghemite nanocomposites were prepared by aging a mixture of magnetite nanoparticles (NPs), sand and Portland cement. Diverse spectroscopies and magnetometry revealed that the nanocomposites incorporate maghemite NPs in the concrete structure. Scanning electron microscopy also revealed the presence of maghemite NPs and variations on the surface morphology of concrete. Regarding the evaluation of the arsenic removal properties of concrete/maghemite nanocomposite, it was found that the addition of the NPs improved the arsenic removal capacity of concrete. Batch studies revealed that the adsorption isotherms fitted to the Gunary isotherm model. Furthermore, column studies demonstrated the application of the nanocomposites for arsenic removal from well water under dynamic conditions. Using the bed depth service time model for the evaluation of the column performance, it was shown that the columns of concrete/maghemite nanocomposites can diminish the

Download

Phase Selection during Solidification of Ni-10.95 at. % and B-3.23 at. % Si Alloy

Metals, 2017

To gain insight into the solidification of the Ni-10.95 at. % and B-3.23 at. % Si alloy, 29 cast ... more To gain insight into the solidification of the Ni-10.95 at. % and B-3.23 at. % Si alloy, 29 cast samples extracted from a casting of this alloy were remelted under an Ar atmosphere, using either DSC or an in-house thermal analysis apparatus. Ni(fcc) and Ni 3 B phases were identified by X-ray diffraction of both the remelted and original cast samples; however, microstructural differences were observed between the two. These microstructural differences are associated with the high undercooling observed during the eutectic reaction in the remelted samples. This high undercooling results from the difficulty of Ni 3 B nucleation, which allows the formation of a Ni x B y metastable phase. Metallographic inspection shows that the metastable phase solidifies at least partially through a non-cooperative growth mechanism. This metastable phase may be the elusive Ni 23 B 6 phase. The melting temperature of the metastable phase is 985 • C, and it solidifies below 943 • C under the experimental conditions used in this study. The temperature of solid transformation of the metastable constituent to Ni 3 B and Ni is strongly dependent on the amount of Ni 3 B formed during solidification. The minimal temperature of such transformation, 834 • C, corresponds to samples where Ni 3 B solidification was not detected in the thermal curves.

$Figure 1. In-house thermal analysis apparatus. > ei Maia” mi (aa as: ae To identify phases in the samples at room temperature, X-ray diffraction was performed for several bulk samples. XRD measurements were performed on a PANalytical X-ray diffractometer, model EMPYREAN (PANalytical, Almelo, The Netherlands). The measurements were performed during 36,034 s, from 20 to 80 degree with a pitch size of 0.026 degree, using Cu-K« incident radiation with a nickel filter. To index XRD pattern peaks, all phases expected according to main constituents from chemical composition and with available JCFDS cards were tested. The JCFDS cards for Nij3Bg, that were tested to index XRD peaks were the 01-073-7324 and the 01-074-3232, both considered in hypothetic quality. The JCFDS cards that applied to index the diffractograms were 03-065-2865 and 01-082-1699 that correspond to Ni and Ni3B, respectively. 3. Results and Discussion$

$Figure 4. X-ray diffractograms of the Ni-10.95 at. % B-3.23 at. % Si samples at room temperature that show different reaction sequences in the CCT thermal curves: (a) R1s-R2, and (b) R1.-R35-(R2s-R4). Both samples were obtained at 5 °C/min cooling rate. Figure 4. X-ray diffractograms of the Ni-10.95 at. % B-3.23 at. % Si samples at room temperature that$

$Figure 8. (a) Thermal curve and (b) microstructure corresponding to a sample of the Ni-10.95 at. % B-3.23 at. % Si alloy that showed the R1,-R3.-R4 reaction sequence without R2,. The data correspond to a DSC experiment at a cooling rate of 5 °C/min. i eae A a Tes i ae The extreme case where R2, disappears assists to illustrate the microstructure resulting from the solidification of the metastable constituent and its subsequent transformation to the stable constituent. Figure 8a shows a DSC curve with an R1,-R3.-R4 sequence, and the microstructure of the corresponding sample is shown in Figure 8b. This microstructure shows a fibrous constituent and coarse zones of nickel boride with small embedded dots. These small dots are better appreciated in Figure 13b. Besides the fact that this microstructure is quite different from that observed for R1.-R2, reaction sequence, the question arises if the fibrous constituent is formed during solidification or during solid-state transformation. Xu et al. [23] relate the formation of regularly distributed dots, called fibrous constituents here, to a eutectic reaction. This hypothesis is analyzed in the next paragraphs with the support of additional thermal and microstructural evidence. When a sub-disturbance appears in the R3, peak or on the metastable eutectic plateau, two reaction sequences can be identified, depending on the sub-disturbance location. If the latter appears during the initial stages of either the R3; peak or the metastable eutectic plateau, see Figure 9a,b, then R4 is not observed as a unique peak. As the X-ray diffractograms show only stable constituents, R4 must be overlapped with the R2, solidification reaction. In this case, the overall reaction sequence is noted as R1s-R3,-(R2,-R4). The sequence in parentheses means that R2, is followed by overlapping of R4. This hypothesized sequence (R2;-R4) is based on the fact that the transformation of metastable Ni,By must depend essentially on the nucleation of Ni3B. When the latter appears in appreciable quantity during solidification, then Ni,By could easily begin to transform into Ni3B and Ni, as the nucleation barrier is overcome and a large amount of surface contact between the Ni3B and Ni,By phases is available. This circumstance occurs in the R1,-R3,-(R2,-R4) reaction sequence, where the important presence of Ni3B as part of the anomalous eutectic is observed, see Figure 9c,d. ee Ap a ae a a . ay a nie —_~m _— aa aa a$

Download

Characterization of Inclusion Populations in Mn-Si Deoxidized Steel

Metallurgical and Materials Transactions B, 2017

Four plant heats of Mn-Si deoxidized steel were conducted to follow the evolution of the inclusio... more Four plant heats of Mn-Si deoxidized steel were conducted to follow the evolution of the inclusion population through ladle furnace (LF) treatment and subsequent vacuum treatment (VT). The liquid steel was sampled, and the chemical composition and size distribution of the inclusion populations were characterized. The Gumbel generalized extreme-value (GEV) and generalized Pareto (GP) distributions were used for the statistical analysis of the inclusion size distributions. The inclusions found at the beginning of the LF treatment were mostly fully liquid SiO 2-Al 2 O 3-MnO inclusions, which then evolved into fully liquid SiO 2-Al 2 O 3-CaO-MgO and partly liquid SiO 2-CaO-MgO-(Al 2 O 3-MgO) inclusions detected at the end of the VT. The final fully liquid inclusions had a desirable chemical composition for plastic behavior in subsequent metallurgical operations. The GP distribution was found to be undesirable for statistical analysis. The GEV distribution approach led to shape parameter values different from the zero value hypothesized from the Gumbel distribution. According to the GEV approach, some of the final inclusion size distributions had statistically significant differences, whereas the Gumbel approach predicted no statistically significant differences. The heats were organized according to indicators of inclusion cleanliness and a statistical comparison of the size distributions.

Download

Photocatalytic activity of kaolinite

Catalysis Communications, 2011

The photocatalytic activity of commercial kaolinite (KGa-1b) was evaluated for the degradation of... more The photocatalytic activity of commercial kaolinite (KGa-1b) was evaluated for the degradation of methylene blue (MB) in aqueous suspension and of toluene in the gas phase. An enhanced photolysis of MB in the presence of kaolinite was detected, albeit at a slower rate than in the presence of the same mass of commercial TiO 2 P25. Toluene removal under realistic ambient concentrations was catalyzed by both KGa-1b and P25; however, on a TiO 2 content normalized basis, the clay mineral showed a higher photocatalytic rate. In the latter case, toluene degradation was found to be coupled to the presence of kaolinite surfaces, and not proportional to TiO 2 content.

Download

Evaluation of Steel Cleanliness in a Steel Deoxidized Using Al

Metallurgical and Materials Transactions B, 2016

The effect of magnesium in the aluminum used as a deoxidizer on the cleanliness of steel was stud... more The effect of magnesium in the aluminum used as a deoxidizer on the cleanliness of steel was studied throughout a steelmaking route for the production of thin slabs. Two deoxidizers with different Mg contents were used. The Mg content of a ''typical'' deoxidizer was~0.5 wt pct Mg, whereas that for an alternative deoxidizer was~2 wt pct Mg. The inclusion population at different stages of the steelmaking process was characterized in terms of chemical composition, number, and size distribution. The inclusion modification path shows that the solid Al 2 O 3 and Al 2 O 3-MgO inclusions formed in the early stage of the steel ladle treatment are modified into Al 2 O 3-MgO-CaO liquid and MgO-Al 2 O 3-liquid inclusions. Although some slight differences were observed in the ladle furnace samples, the chemical composition of inclusions was similar in the samples taken at the mold of the continuous casting, regardless of the deoxidizer used. Gumbel, generalized extreme value (GEV), and generalized Pareto (GP) distributions were used for the description of the size distribution. The GEV and GP distributions resulted in proper distributions to describe the evolution of size distribution throughout the steelmaking process. Furthermore, no statistically significant differences between inclusion size distributions resulting from the use of either deoxidizer were found.

Download

Induration Process of Pellets Prepared from Mixed Magnetite–35% Hematite Concentrates

ISIJ International, 2014

To explore the possibility of successfully processing iron ore pellets with a high content of hem... more To explore the possibility of successfully processing iron ore pellets with a high content of hematite, thermogravimetric tests were performed to study the induration process of pellets composed of a mixture of iron ore concentrates (magnetite and 35% wt of hematite). Thermogravimetric tests were performed nonisothermally from 25°C to 1 400°C using two heating rates, 5 and 50°C/min. To identify the reactions involved and to follow the microstructural evolution throughout the induration process, selected tests were arrested at predetermined temperatures, and samples were rapidly cooled to room temperature for later characterization using X-ray diffraction (XRD) and scanning electron microscopy (SEM) along with energy dispersive spectroscopy (EDS). It was found that the formation of phases such as calcium ferrite (CF), magnesium ferrite (MF), silico-ferrites of calcium (SCF) and silico-ferrites of calcium and aluminum (SCFA) are influenced by the heating rate. The microstructure of the fired pellet processed at 50°C/min showed compact small grains of the sintered phase of the secondary hematite (SH), partially surrounded by a slag phase. In contrast, the fired pellet processed at 5°C/min exhibited a microstructure consisting of the SH phase with a faceted morphology surrounded by a relatively large amount of the slag phase. The results suggest that the pellet processed at 50°C/min had a more satisfactory response to the induration process.

Download