scholarly journals Phase and structural transformations when forming a welded joint from rail steel. Report 1. Thermokinetic diagram of decomposition of supercooled austenite of R350LHT rail steel

2021 ◽  
Vol 64 (2) ◽  
pp. 95-103
Author(s):  
E. V. Polevoi ◽  
Yu. N. Simonov ◽  
N. A. Kozyrev ◽  
R. A. Shevchenko ◽  
L. P. Bashchenko
Keyword(s):  
Diffusion Processes ◽  
Rail Steel ◽  
Physical And Mechanical Properties ◽  
High Hardness ◽  
Supercooled Austenite ◽  
Austenite Decomposition ◽  
Thermokinetic Diagram ◽  
Optimal Parameters ◽  
Higher Temperature ◽  
Martensite Structure

A thermokinetic diagram of decomposition of supercooled austenite of R350LHT steel was constructed based on the results of its dilatometric, metallographic and hardness analysis during continuous cooling and in isothermal conditions. It was found that cooling at a rate of 0.1 and 1 °C/s causes the austenite decomposition in R350LHT steel by the pearlite mechanism. After cooling at a lower rate, the pearlite structure is coarser and has lower hardness (289 HV). This is due to the higher temperature range of transformation, in which diffusion processes associated with the transformation of austenite into pearlite occur more actively. In the range of rates from 5 to 10 °C/s, the austenite decomposition occurs according to the pearlite and martensitic mechanism, which leads to the formation of a pearlite-martensite structure. When the austenite of the steel under study is cooled at a rate of 30 and 100 °C/s, the austenite transforms according to the martensitic mechanism, and a martensitic structure with high hardness is formed. With an increase in the cooling rate of R350LHT steel, an increase in hardness is observed from 289 (at 0.1 °C/s) to 864 – 0 896 HV (at 100 and 30 °C/s, respectively). The conducted studies allow the boundaries of the search for optimal parameters of welding and heat treatment modes of the investigated rail steel to be narrowed. To obtain the required structures and physical and mechanical properties (austenite of R350LHT steel undergoes decomposition by the pearlite mechanism), cooling should be carried out at a rate of no more than 1 °С/s.

scholarly journals Phase transformations occurring during the formation of a welded joint from rail steel

2021 ◽  
Vol 330 ◽  
pp. 02007
Author(s):  
Alexey Yuryev ◽  
Nikolay Kozyrev ◽  
Roman Shevchenko ◽  
Alexey Mikhno ◽  
Olga Gutak
Keyword(s):  
Phase Transformations ◽  
Welded Joint ◽  
Rail Steel ◽  
Supercooled Austenite ◽  
Austenite Decomposition ◽  
Hardness Testing ◽  
Continuous Cooling Transformation ◽  
Continuous Cooling ◽  
Continuous Cooling Transformation Diagrams ◽  
Transformation Diagrams

The results of dilatometry, metallography and hardness testing of the decomposition process of supercooled austenite of R350LHT steel are presented. During continuous cooling and in isothermal conditions, continuous cooling transformation diagrams of supercooled austenite decomposition of steel R350LHT are constructed.

Effects of Sintering Variables on the Physical and Mechanical Properties of Metal Injection Molding Molded 17-4 PH Stainless Steel

2021 ◽  
Vol 1028 ◽  
pp. 403-408
Author(s):  
Apang Djafar Shieddieque ◽  
Shinta Virdhian ◽  
Moch Iqbal Zaelana Muttahar ◽  
Muhammad Rafi Muttaqin
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Injection Molding ◽  
Relative Density ◽  
Physical And Mechanical Properties ◽  
High Hardness ◽  
Argon Atmosphere ◽  
Metal Injection Molding ◽  
Manufacturing Method ◽  
Small Complex

Metal injection molding (MIM) is a near net shape manufacturing technique for producing small, complex, precision parts in mass production. MIM process is manufacturing method that combines traditional shape-making capability of plastic injection molding and the materials flexibility of powder metallurgy. The process consists of the following four steps: mixing of metal powder and binder, injection molding to shape the component, debinding to remove the binder in the component, sintering to consolidate the debound parts. In this research, the physical and mechanical properties of metal injection molded 17-4 PH stainless steel were investigated with the variation of sintering temperatures (1300 °C - 1360 °C) and atmosphere conditions (argon and vacuum conditions). The relative density, microstructure, distortion, and hardness are measured and analyzed in this study. The results show that highest relative density of 87%, relative homogeneous shrinkage and high hardness are achieved by sintering at 1360 °C for 1.5 hours and argon atmosphere. At the same sintering temperature and time, sintering in vacuum shows lower relative density (81%) than that in argon condition due to pores growth. The pore growths were not observed in the argon atmosphere. It can be concluded that sintering stages more rapidly under vacuum condition. The hardness measurements result also showed that high hardness is obtained by high density parts. The optimum average hardness obtained in this study is 239 HV. However, the hardness properties results are still lower than 280 HV according to MPIF Standard 35 for MIM parts.

scholarly journals THE EFFECT OF SODIUM SILICATE AND ITS SOLUTION ON THE PROPERTIES OF REFRACTORY COMPLEX BINDER/NATRIO SILIKATO KIEKIO IR JO TIRPALO TANKIO ĮTAKA KOMPLEKSINIO KAITRAI ATSPARAUS RIŠIKLIO SAVYBĖMS

1999 ◽  
Vol 5 (3) ◽  
pp. 211-216
Author(s):  
Valentin Antonovič ◽  
Stasys Goberis ◽  
Romualdas Mačiulaitis
Keyword(s):  
Sodium Silicate ◽  
Liquid Glass ◽  
Solid Phase ◽  
Physical And Mechanical Properties ◽  
Alumina Cement ◽  
Hardening Mechanism ◽  
Temperature Range ◽  
Calcium Hydrosilicates ◽  
Higher Temperature ◽  
Complex Binder

In order to improve thermal and mechanical characteristics of a traditional binder with liquid glass a complex binder consisting of liquid glass, its hardener and alumina cement (“Gorkal 70” containing not less than 70 per cent of AI2O3) was tested. Sodium silicate and its solution effect on physical and mechanical properties of a new refractory complex binder (Table 1, Fig 2) were investigated. The results obtained show that compressive strength of binding compound with high quantity of sodium silicate (N3) is the lowest after it had been cured, dried and fired at 300–600°C (Fig 3). It was also found that the strength of a complex binder with small quantity of sodium silicate (N1) in the temperature range of 20–600°C is 2–3 times as high as that of a traditional binder with dispersed fire-clay. The study in the formation of the structure of a complex binders dilatometric tests have also been made. After initial heating at 80–500°C the compositions contracted (Fig 4) due to dehidratation. At the temperature range of 580–750°C the contraction of compositions continue due to reactions at the solid phase. The hypothesis of the hardening mechanism in the complex binder was proposed. Liquid glass tends to restrain the hydration of the alumina cement though hardeners and sodium silicate interaction result in the intense formation of sodium calcium hydrosilicates. Therefore, a complex binder contains less sodium silicate than a traditional one while being used at higher temperature.

Increasing the Performance of Machinery Tools by Super Hard Nanostructured Materials Reinforced with Nanoporous Aluminium Oxide

2013 ◽  
Vol 829 ◽  
pp. 482-486
Author(s):  
Hojatolah Rezaei ◽  
Hamid Omidvar ◽  
Reza Pooladi
Keyword(s):  
Vapour Deposition ◽  
Cutting Tools ◽  
Aluminium Oxide ◽  
Physical And Mechanical Properties ◽  
Young Modulus ◽  
High Hardness ◽  
Coating Methods ◽  
Aluminium Coating ◽  
Research Centres ◽  
Better Than

The use of nanostructured thin films to improve physical and mechanical properties of cutting tools have been recently achieved wonderful progress in industrial and research centres. In this present work, anodic aluminium oxide (AAO) film is formed on the cutting tool by anodizing a thin film of aluminium foil. Aluminium coating is performed using an innovative electroplating method. Then the nanometric pores which are formed by the anodizing are filled with the resistant AlTiN using physical vapour deposition (PVD) method. This procedure results in a nanostructure with an aluminium oxide resistant texture which attains a high hardness and Young modulus. In this project we succeeded in designing aluminium oxide nanostructured as scaffolds for aluminium titanium nitride. Along with nanostructured alloy AlTiN, a unique hardness and wear resistance is obtained. This coating texture improvements the efficiency and tool life much better than other coating methods done, and as a result, a greater efficiency in production and reduction in costs is achieved.

Physical and Mechanical Properties of Mo5X3+α (X=Si, B, C) Single Crystals

2002 ◽  
Vol 753 ◽  
Author(s):  
Taisuke Hayashi ◽  
Kazuhiro Ito ◽  
Katsushi Tanaka ◽  
Masaharu Yamaguchi
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Single Crystals ◽  
Plastic Anisotropy ◽  
Physical And Mechanical Properties ◽  
Structure Type ◽  
Advanced Materials ◽  
Anisotropy Ratio ◽  
Higher Temperature ◽  
Better Than

ABSTRACTMo5X3+α (X=Si, B, C) intermetallic compounds such as Mo5SiB2 (D8l), Mo5Si3 (D8m) and Mo5Si3C (D88) have a great potential for ultra-high temperature applications. The present study was undertaken putting greater emphasis on clarifying how their physical and mechanical properties are similar or different in terms of a structure type. Some interesting features are summarized in this paper.The resistivity of Mo5SiB2, Mo5Si3 and Mo5Si3C single crystals exhibited a negative curvature (d2ρ(T)/dT2<0), with a tendency towards saturation. In the Mo5Si3C with large ρ0 due to impurity carbon atoms, resistivity saturation is pronounced. In contrast, a much higher temperature is required to reach saturation in the Mo5SiB2. The anisotropy ratio of CTE (αc/αa) for the Mo5SiB2 is about 1.2–1.6 and is significantly reduced from about 2 of the Mo5Si3 and Mo5Si3C. On the other hand, the Young's modulus of the Mo5SiB2 is more anisotropic than those of the Mo5Si3 and Mo5Si3C. Plastic anisotropy was observed in the Mo5SiB2, because only slip on [001] {100} is operative at 1500°C. On the contrary, plastic deformation was observed at temperatures above 1300°C for the Mo5Si3C and Mo5Si3. Anisotropy of their plastic deformation was much less than that of the Mo5SiB2, presumably because more than two slip systems can be activated. Creep resistance of the Mo5SiB2 is much better than that of the Mo5Si3 as well as the most advanced materials such as MoSi2 and Si3N4 based structural ceramics.

A Feasibility Study on Laser-Mechanical Drilling of SiC Ceramics

2010 ◽  
Vol 447-448 ◽  
pp. 81-85
Author(s):  
Chandra Nath ◽  
Gary Ka Lai Ng ◽  
Gnian Cher Lim ◽  
Jeong Hoon Ko
Keyword(s):  
Thermal Damage ◽  
Physical And Mechanical Properties ◽  
High Hardness ◽  
Hole Drilling ◽  
Taper Angle ◽  
Hole Edge ◽  
Sic Ceramics ◽  
Hostile Environments ◽  
Coated Carbide

Structural SiC (α-type) is believed to be widely applied in hostile environments such as high-temperature, high-corrosive applications in the semiconductor industries due to its superior thermo-physical and mechanical properties. However, the extremely high hardness and brittleness of SiC makes hole drilling difficult by the conventional mechanical drilling (CMD) technique. Laser can be used to drill SiC; but the resultant holes are often tapered and uneven, with tendency for microcracks and thermal damage to occur at the hole entry due to the high thermal shock from the laser. This paper reports on the experimental results of a sequential laser-mechanical drilling (LMD) technique for drilling α-SiC. At first, an Nd:YAG laser was used to drill a series of pilot holes on a 3 mm thick SiC plate. Then a diamond-coated carbide drill was sequentially applied to these holes to obtain desired hole diameter of 0.5 mm. A number of through holes on SiC (aspect ratio: 6) were successfully obtained using this approach. The quality of the drilled holes were assessed in terms of the entrance and exit sizes and conditions, hole taper angle, hole edge shapes, and microcracks. Finally, comparisons of the LMD performances were also made against the holes predrilled by the laser itself and holes of the similar size drilled separately with the CMD technique. The experiment results show that the proposed drilling approach can effectively drill α-SiC ceramics.

Grain-Size and Impurity Effects in Low-Temperature Deposition of TiN

1996 ◽  
Vol 438 ◽  
Author(s):  
H. Kakimy ◽  
F. Namavar ◽  
E. Tobin ◽  
J. Haupt ◽  
R. Bricault ◽  
...  
Keyword(s):  
Grain Size ◽  
Ion Beam ◽  
Physical And Mechanical Properties ◽  
High Hardness ◽  
Deposition Process ◽  
Impurity Effects ◽  
Tin Films ◽  
Tin Coatings ◽  
Tin Thin Films ◽  
Temperature Deposition

AbstractCommercially deposited titanium nitride (TIN) thin films have been available daring recent years. These TiN films possess high hardness and have good wear resistance; however, the deposition process typically requires a temperature of 500°C or higher. In many cases, due to substrate characteristics, a deposition temperature below 150°C is required in order to exploit TiN coating properties.The objective of this work is to demonstrate that ion beam assisted deposition (IBAD) makes it possible to deposit gold-color TiN films with good adhesion onto a variety of substrates including plastics at temperatures below 150°C. These films have physical and mechanical properties as good as those produced at high temperatures. Samples have also been examined by nanohardness techniques to accurately determine the hardness of the films and relate them to process parameters and crystal sizes. Our results indicate that, by controlling the grain size of TiN, it is possible to fabricate TiN coatings at room temperature with hardness as high as 25.5 ± 1 GPa.

Synthesis, Characterization and Mechanical Properties of Silicon Carbide Nanowires

2010 ◽  
Author(s):  
Huan Zhang ◽  
Weiqiang Ding ◽  
Daryush Aidun
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Silicon Carbide ◽  
Physical And Mechanical Properties ◽  
High Hardness ◽  
High Strength ◽  
Harsh Environments ◽  
Low Density ◽  
Low Thermal Expansion ◽  
Oxidation And Corrosion

Silicon carbide (SiC) material has many outstanding physical and mechanical properties such as high strength, high hardness, low density, high thermal conductivity, low thermal expansion coefficient, large band-gap, and excellent oxidation and corrosion resistances [1–3]. It is a leading material for components and devices operating at high temperature, high power and under harsh environments [4–5]. Micro-sized SiC particles and whiskers are commonly used as reinforcement materials for ceramics, metals and alloys in various structural and tribological applications [6–7].

scholarly journals Structural differences between reaction wood and opposite wood with different drying temperatures

BioResources ◽  
2020 ◽  
Vol 15 (2) ◽  
pp. 4407-4416
Author(s):  
Ivan Klement ◽  
Tatiana Vilkovská ◽  
Peter Vilkovský ◽  
Štěpán Hýsek
Keyword(s):  
Physical And Mechanical Properties ◽  
Thick Wall ◽  
Normal Wood ◽  
Reaction Wood ◽  
Drying Time ◽  
Fiber Cells ◽  
Opposite Wood ◽  
Negative Effect ◽  
Higher Temperature ◽  
End Times

Reaction wood is characterized by having different anatomical and chemical features than normal wood. The different composition of cell walls, the higher quantitative proportion of thick-wall fiber cells, diameter, and the abundance of vessels have remarkable effects on reaction wood’s physical and mechanical properties. Reaction wood has fewer vascular cells. In addition, it has a smaller lumen diameter, which results in reduced permeability. Therefore, reaction wood is more difficult to dry at a certain moisture content. The differences in the drying times of the reaction wood and the normal wood were largest at a temperature of 60 °C and durations greater than 30 h, and the reaction wood dried more slowly. At a temperature of 120 °C, the differences in drying time were minimalized, and drying end times were almost identical. The expected negative effect of higher temperature on the morphology of reaction wood and opposition wood was not confirmed.

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