scholarly journals Effects of Primarily Solidified Dendrite and Thermal Treatments on the M23C6 Precipitation Behavior of High-Chromium White Iron

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1690
Author(s):  
Young-Gy Song ◽  
Jun-Seok Oh ◽  
Baig-Gyu Choi ◽  
Chang-Yong Jo ◽  
Je-Hyun Lee
Keyword(s):  
Heat Treatment ◽  
Thermal Treatment ◽  
Low Temperature ◽  
M23c6 Carbide ◽  
Thermal Treatments ◽  
White Iron ◽  
Precipitation Behavior ◽  
High Chromium ◽  
Conventional Heat Treatment

The precipitation behavior of M23C6 carbide during thermal treatment of high-Cr white iron with various fractions of primarily solidified dendrite was studied and reviewed. M23C6 precipitation in the primarily solidified dendrite occurred preferentially during conventional heat treatment, whereas it occurred scarcely in the eutectic austenite. The reaction between M7C3 and austenite caused the dissolution of M7C3 into austenite, followed by precipitation of M23C6 along the periphery of eutectic M7C3. Relatively low-temperature thermal treatment (modified heat treatment) led to precipitation of M23C6 particles in the eutectic austenite, which is presumed to be caused by solubility difference depending on temperature.

scholarly journals Effect of Dendrite Fraction on the M23C6 Precipitation Behavior and the Mechanical Properties of High Cr White Irons

Metals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1576
Author(s):  
Jun-Seok Oh ◽  
Young-Gy Song ◽  
Baig-Gyu Choi ◽  
Chalothorn Bhamornsut ◽  
Rujeeporn Nakkuntod ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Primary Dendrite ◽  
Carbide Precipitation ◽  
Eutectic Phase ◽  
M23c6 Carbide ◽  
Eutectic Solidification ◽  
Precipitation Behavior ◽  
Conventional Heat Treatment ◽  
High Fraction

High Cr white irons with various fractions of primary dendrite have been prepared through the modification of their chemical composition. Increasing C and Cr contents decreased the primary dendrite fraction. Eutectic solidification occurred with the phase fraction ratio of austenite: M7C3 = 2.76:1. The measured primary dendrite fractions were similar to the calculated results. ThermoCalc calculation successfully predicted fractions of M7C3, austenite, and M23C6. Conventional heat treatment at high temperature caused a destabilization of austenite, releasing it’s solute elements to form M23C6 carbide. Precipitation of M23C6 during destabilization preferentially occurred within primary (austenite) dendrite, however, the precipitation scarcely occurred within austenite in eutectic phase. Thus, M23C6 precipitation by destabilization was relatively easy in alloys with a high fraction of primary dendrite.

scholarly journals Carbonitration of a Tool for Pressing Stainless Steel Pipes

2020 ◽  
Vol 7 (2) ◽  
pp. C17-C21
Author(s):  
I. V. Ivanov ◽  
M. V. Mohylenets ◽  
K. A. Dumenko ◽  
L. Kryvchyk ◽  
T. S. Khokhlova ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Thermal Treatment ◽  
Heat Resistance ◽  
Alkali Metals ◽  
Matrix Ring ◽  
High Hardness ◽  
Operating Conditions ◽  
Matrix Rings ◽  
Conventional Heat Treatment ◽  
The Stability

To upgrade the operational stability of the tool at LLC “Karbaz”, Sumy, Ukraine, carbonation of tools and samples for research in melts of salts of cyanates and carbonates of alkali metals at 570–580 °C was carried out to obtain a layer thickness of 0.15–0.25 mm and a hardness of 1000–1150 НV. Tests of the tool in real operating conditions were carried out at the press station at LLC “VO Oscar”, Dnipro, Ukraine. The purpose of the test is to evaluate the feasibility of carbonitriding of thermo-strengthened matrix rings and needle-mandrels to improve their stability, hardness, heat resistance, and endurance. If the stability of matrix rings after conventional heat setting varies around 4–6 presses, the rings additionally subjected to chemical-thermal treatment (carbonitration) demonstrated the stability of 7–9 presses due to higher hardness, heat resistance, the formation of a special structure on the surface due to carbonitration in salt melts cyanates and carbonates. Nitrogen and carbon present in the carbonitrided layer slowed down the processes of transformation of solid solutions and coagulation of carbonitride phases. The high hardness of the carbonitrified layer is maintained up to temperatures above 650 °C. If the stability of the needle-mandrels after conventional heat treatment varies between 50–80 presses, the needles, additionally subjected to chemical-thermal treatment (carbonitration) showed the stability of 100–130 presses due to higher hardness, wear resistance, heat resistance, the formation of a special surface structure due to carbonitration in melts of salts of cyanates and carbonates. Keywords: needle-mandrel, matrix ring, pressing, heat treatment, carbonitration.

Molecular Beam Epitaxy on the (NH4)2Sx-Treated Surface of GaAs

1989 ◽  
Vol 148 ◽  
Author(s):  
H. Oigawa ◽  
M. Kawabe ◽  
J.-F. Fan ◽  
Y. Nannichi
Keyword(s):  
Heat Treatment ◽  
Low Temperature ◽  
Molecular Beam ◽  
Schottky Barrier Height ◽  
Surface States ◽  
Monomolecular Layer ◽  
Ammonium Sulfide ◽  
Conventional Heat Treatment ◽  
Low Temperature Gaas ◽  
Excess Sulfur

ABSTRACTWe have found that treatment with a solution of ammonium sulfide containing excess sulfur [(NH4) 2Sx] produced a stabilized surface of GaAs. The treated surface is covered with a monomolecular layer of sulfur, and oxygen atoms are prohibited from adsorbing chemically on this surface. We checked the durability of the treated surface to heat treatment to find that it was stable up to more than 500 °C. Epitaxial growth of an Al film was demonstrated on the (NH4) 2Sx-treated surface. The presence of sulfur atoms at the interface by this treatment was found to suppress the chemical reaction between the metal and GaAs. Low temperature GaAs epitaxy was demonstrated on the sulfide treated surface without conventional heat treatment. The surface treatment correlates with changes in Schottky barrier height with various metals, which suggests that the surface states of GaAs are decreased remarkably.

The Effect of Heat Treatment and Welding Parameters on the Corrosion Behaviour of a Friction Stir Welded 6056 Aluminium Alloy

2008 ◽  
Vol 38 ◽  
pp. 285-297
Author(s):  
T. Monetta ◽  
M. Montuori ◽  
Antonio Squillace ◽  
Francesco Bellucci
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Thermal Treatment ◽  
Aluminium Alloy ◽  
Intergranular Corrosion ◽  
Corrosion Behaviour ◽  
Welding Parameters ◽  
Thermal Treatments ◽  
Friction Stir ◽  
Parent Alloy

The current research has assessed the correlation between welding parameters and corrosion behaviour for friction stir welded 6056 aluminium alloy. Different thermal treatments and welding parameters were considered. For the welding parameters studied in this project, the data strongly indicate that sensitivity to corrosion is linked to the welding parameters employed. Substantial differences were found for the higher and lower speed welding parameters, with the lower speed parameters appearantly resulting in less corrosion resistance. The most widespread form of corrosion observed was pitting; however, intergranular corrosion (IGC) was also seen. While the T78 thermal treatment appears to decrease the corrosion resistance of the parent alloy, the weld region tends to improve, with the nugget being cathodic.

scholarly journals LOW-TEMPERATURE SYNTHESIS OF BARIUM TITANITE IN AQUEOUS SOLUTION

2018 ◽  
Vol 61 (12) ◽  
pp. 56-62 ◽  
Author(s):  
Alexandr V. Agafonov ◽  
Konstantin V. Ivanov ◽  
Olga V. Alekseeva
Keyword(s):  
Heat Treatment ◽  
Barium Titanate ◽  
Thermal Treatment ◽  
Low Temperature ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Temperature Phase ◽  
Low Temperature Synthesis ◽  
Temperature Synthesis

Barium titanate powder with average particle size near 300 nm was produced using the low-temperature synthesis. It was established using scanning electron microscopy that at the thermal treatment, the particles gradually decrease with the formation of polydisperse aggregates. Based on the thermogravimetric analysis of the synthesized powder held in air for 4 months, it was shown that along with the low-temperature phase, the sample contains a high-temperature phase of carbonates, which removes at ~ 900 °C. Sorption characteristics of barium titanate thermally treated at various temperatures were obtained from the results of adsorption-desorption of nitrogen vapors. The specific surface area of the BaTiO3 powder was 76 m2/g. It was found that further heat treatment leads to a decrease in the specific surface area. The X-ray diffraction analysis of barium hydroxotitanil annealed at temperatures from 120 °C to 800 °C showed that the thermal treatment of the sample leads to the formation of a completely formed phase of barium titanate. The DSC temperature was used to determine the Curie temperatures for a HTB powder thermally treated in the temperature range from 120 to 800 °C. Dielectric spectra of suspensions of the synthesized powder were obtained during the heat treatment. <span style="opacity: 0;"> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . </span>

Improvement of the Reverse Characteristics of Ti/4H-SiC Schottky Barrier Diodes by Thermal Treatments

2007 ◽  
Vol 124-126 ◽  
pp. 105-108 ◽  
Author(s):  
Dae Hwan Kim ◽  
Jong Ho Lee ◽  
Jeong Hyun Moon ◽  
Myong Suk Oh ◽  
Ho Keun Song ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Thermal Treatment ◽  
Schottky Barrier ◽  
Breakdown Voltage ◽  
Schottky Barrier Height ◽  
Xrd Analysis ◽  
Silicide Phase ◽  
Thermal Treatments ◽  
Schottky Barrier Diodes ◽  
Treatment Conditions

Ti/4H-SiC Schottky barrier diodes were fabricated under 500, 750, 1000 °C thermal treatment conditions. After the heat treatment at 750 °C, formation of TiC(111) and Ti5Si3(210) phases was confirmed by XRD analysis. Formation of Ti carbide and silicide phase increased breakdown voltage VB from 545 V to 830 V. An improvement of breakdown voltage (VB) was observed in case of the thermal treatment in nitrogen ambient at 750 °C for 2 min. Ideality factor (n), specific on resistance (Ron), and Schottky barrier height (Φb) were 1.04, 2.7 m-cm2, 1.33 eV respectively.

scholarly journals Processing by Additive Manufacturing Based on Plasma Transferred Arc of Hastelloy in Air and Argon Atmosphere

Metals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 200 ◽  
Author(s):  
Eva M. Perez-Soriano ◽  
Enrique Ariza ◽  
Cristina Arevalo ◽  
Isabel Montealegre-Melendez ◽  
Michael Kitzmantel ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Additive Manufacturing ◽  
Thermal Treatment ◽  
Cooling Rate ◽  
Air Cooling ◽  
Thermal Treatments ◽  
Processing Conditions ◽  
Plasma Transferred Arc ◽  
Deformation Properties ◽  
Transferred Arc

This research was carried out to determinate the effect of the atmosphere processing conditions (air and argon) and two specific thermal treatments, on the properties of specimens made from the nickel-based alloy Hastelloy C-22 by plasma transferred arc (PTA). Firstly, the additive manufacturing parameters were optimized. Following, two walls were manufactured in air and argon respectively. Afterwards, a determinate number of specimens were cut out and evaluated. Regarding the comparison performed with the extracted specimens from both walls, three specimens of each wall were studied as-built samples. Furthermore, a commonly used heat treatment in Hastelloy, with two different cooling methods, was selected to carry out additional comparisons. In this respect, six additional specimens of each wall were selected to be heat treated to a temperature of 1120 °C for 20 min. After the heat treatment, three of them were cooled down by rapid air cooling (RAC), while the other three were cooled down by water quenching (WQ). In order to study the influence degree of the processing conditions, and how the thermal treatments could modify the final properties of the produced specimens, a detailed characterization was performed. X-ray diffraction and microstructural analyses revealed the phases-presence and the apparition of precipitates, varying the thermal treatment. Moreover, the results obtained after measuring mechanical and tribological properties showed slight changes caused by the variation of the processing atmosphere. The yield strength of the extracted specimens from the two walls achieved values closer to the standards ones in air 332.32 MPa (±21.36 MPa) and in argon 338.14 MPa (±9 MPa), both without thermal treatment. However, the effect of the cooling rate resulted as less beneficial, as expected, reducing the deformation properties of the specimens below 11%, independently of the air or argon manufacturing atmosphere and the cooling rate procedure.

Vanadium Additions to a High-Cr White Iron and its Effects on the Abrasive Wear Behavior.

MRS Advances ◽  
2020 ◽  
Vol 5 (59-60) ◽  
pp. 3077-3089
Author(s):  
Alexeis Sánchez ◽  
Arnoldo Bedolla-Jacuinde ◽  
Francisco V. Guerra ◽  
I. Mejía
Keyword(s):  
Heat Treatment ◽  
Abrasive Wear ◽  
Volume Fraction ◽  
Wear Behavior ◽  
Wear Behaviour ◽  
White Iron ◽  
Heat Treated ◽  
Bulk Hardness ◽  
Abrasive Wear Behavior ◽  
Vanadium Carbides

AbstractFrom the present study, vanadium additions up to 6.4% were added to a 14%Cr-3%C white iron, and the effect on the microstructure, hardness and abrasive wear were analysed. The experimental irons were melted in an open induction furnace and cast into sand moulds to obtain bars of 18, 25, and 37 mm thickness. The alloys were characterized by optical and electronic microscopy, and X-ray diffraction. Bulk hardness was measured in the as-cast conditions and after a destabilization heat treatment at 900°C for 45 min. Abrasive wear resistance tests were undertaken for the different irons according to the ASTM G65 standard in both as-cast and heat-treated conditions under a load of 60 N for 1500 m. The results show that, vanadium additions caused a decrease in the carbon content in the alloy and that some carbon is also consumed by forming primary vanadium carbides; thus, decreasing the eutectic M7C3 carbide volume fraction (CVF) from 30% for the base iron to 20% for the iron with 6.4%V;but overall CVF content (M7C3 + VC) is constant at 30%. Wear behaviour was better for the heat-treated alloys and mainly for the 6.4%V iron. Such a behaviour is discussed in terms of the CVF, the amount of vanadium carbides, the amount of martensite/austenite in matrix and the amount of secondary carbides precipitated during the destabilization heat treatment.

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