Apparatus for mechanical tests on heat-resistant plastics subjected to uniform unilateral heating

1969 ◽  
Vol 1 (5) ◽  
pp. 557-559
Author(s):  
G. V. Isakhanov ◽  
Yu. M. Rodichev
Keyword(s):  
Mechanical Tests ◽  
Heat Resistant ◽  
Unilateral Heating

Damage Characterization of Heat Resistant Steels After Long Service in Reforming Plants

2016 ◽  
Author(s):  
Antonello Alvino ◽  
Alessandra Antonini ◽  
Daniela Lega ◽  
Canio Mennuti ◽  
Andrea Tonti
Keyword(s):  
Corrosion Resistance ◽  
Chemical Composition ◽  
Creep Damage ◽  
Mechanical Tests ◽  
Coke Deposition ◽  
Process Conditions ◽  
Secondary Phases ◽  
Heat Resistant ◽  
Damage Characterization

ASTM A 297 grade HP steels are widely employed for radiant tubes in reforming furnaces: this class of heat resistant alloys shows high creep and corrosion resistance, ensuring good performances in extreme pressure and temperature conditions. The typical microstructure of such materials is an austenitic matrix surrounded by a network of interdendritic carbides, which contain chromium and other carbide forming elements, namely Nb, Ti, W, Zr and Y. During long service life, these high strength materials may suffer aging or even severe damage, especially when process conditions allow coke deposition, or maintenance procedures are not carried properly. Service aging can be summarized, for HP steels, in terms of microstructure degradation: coalescence and coarsening of interdendritic precipitates, precipitation of secondary carbides in the austenite matrix and transformation of niobium-rich carbides in the G-phase silicide are the typical phenomena occurring on the microstructure of these alloys during service. Carburization can also occur in radiant tubes, since their inner wall side is exposed to hydrocarbon-rich process fluids: carbon diffuses into the metal matrix, causing massive precipitation of chromium-rich carbides. The alloy corrosion resistance is then reduced, resulting in surface attack, cracks development and a general wastage of the material. Furthermore, the high temperatures, which tubes are exposed to, can also induce creep, especially if a local tube overheating occurs: cavities and microcracks, mainly localized at precipitates, are the typical evidences of creep damage on HP steels. The present work is aimed on the damage characterization of several radiant tubes in HP alloys, after long term service aging in reforming plants. We employed optical and electron microscopy, EDX elements mapping and mechanical tests, in order to characterize and evaluate the various damages affecting the alloys. Microstructure evolution has been detected in all the analyzed tubes, but we found that such a phenomenon was strictly influenced by the chemical composition of each alloy, so that in presence of small amounts of titanium and tungsten, the chemical evolution of the secondary phases was appreciably contained. Creep also was observed in all the investigated tubes and its extent was found to be related to both alloy composition and process conditions. These latter have assumed to be the main driving factor for carburization, since we observed that slight differences in temperature, pressure, chemical composition of the process fluid and tube maintenance dramatically conditioned the performances of each tube. Massive precipitation and material degradation, in fact, were found in some cases, but, on the other side, no appreciable evidence of carburization damage was observed on other cases.

scholarly journals Влияние микролегирования иттрием и гафнием на прочностные характеристики и морфологию карбидной фазы сплава ЖС3ДК-ВИ при замедленной кристаллизации

2021 ◽  
pp. 125-131
Author(s):  
Татьяна Владимировна Тихомирова ◽  
Елена Ивановна Гордиенко ◽  
Руслан Васильевич Бехтер ◽  
Александр Витальевич Подобный
Keyword(s):  
Carbide Phase ◽  
Room Temperature ◽  
Crystallization Rate ◽  
Tensile Tests ◽  
Mechanical Tests ◽  
Treatment Temperature ◽  
Strength Characteristics ◽  
Technological Parameters ◽  
Heat Resistant

There are analyzed the melts of the ZhS3DK-VI alloy with different levels of strength characteristics and the factors influencing their reduction, differences in the macro and microstructure of the alloy, the effect of the crystallization rate when pouring the melt into hot and cold ceramic molds are determined. Since when casting parts, the level of properties is determined on separately cast samples, in the technology of manufacturing samples, the casting parameters of the corresponding part must be observed, and when increasing the strength characteristics due to changing technological parameters, it is imperative to consider the possibility of changing the technology of casting parts. However, for parts of complex configuration, cast from heat-resistant nickel alloys, it is often impossible to change the technology, therefore the only way to influence the properties of the material is to use microalloying with rare earth elements, for example, yttrium and hafnium. The introduction of these alloying elements in small amounts has a positive effect on factors that reduce the properties of the ZhS3DK-VI alloy, such as the unfavorable shape and topography of the carbide phase, or even slightly change the chemical composition of carbides. The article analyzes the effect of microalloying with hafnium and yttrium on the morphology and topography of the carbide phase; positive changes in the microstructure and strength characteristics at room temperature of the heat-resistant nickel alloy ZhS3DK-VI are noted. The technology of microalloying the melt has been developed to obtain satisfactory valuesof strength characteristics in tensile tests and impact toughness at room temperature. Microalloying the ZhS3DK-VI alloy with hafnium in a concentration of 0.15...0.25 % made it possible to increase the strength characteristics on samples for mechanical tests by 10…15 %, provided that the melt was drained into hot ceramic molds and slowed down. Higher concentrations of hafnium during slow crystallization lead to the formation of eutectic phases uncharacteristic for the ZhS3DK-VI alloy, requiring a decrease in the heat treatment temperature, which, accordingly, leads to a decrease in the level of long-term strength at 850 °C.

Laser Cladding of Heat-Resistant Iron Based Alloy

2019 ◽  
Vol 822 ◽  
pp. 520-525 ◽  
Author(s):  
Dmitriy V. Masaylo ◽  
Alexey Orlov ◽  
Nikolay G. Razumov ◽  
Anatoly Anatolyevich Popovich ◽  
Vera Popovich
Keyword(s):  
Alloy Powder ◽  
Mechanical Characteristics ◽  
Mechanical Tests ◽  
Raw Material ◽  
Initial Condition ◽  
Heat Resistant ◽  
Treatment Conditions ◽  
Secondary Raw Material ◽  
Iron Based ◽  
Phase And Chemical Composition

Within this work the results of the composition and structural study and mechanical tests of the specimens made from the heat-resistant iron based alloy powder derived from secondary raw material (chips) are presented. The crystalline transformations for the initial condition as well as after several heat treatment conditions were analyzed. Phase and chemical composition were investigated. Mechanical characteristics of the standard flat test bars were defined.

The study of the destruction of heat-resistant chamotte concrete during its sharp heating and cooling

2020 ◽  
pp. 41-46
Author(s):  
V. Antonovich ◽  
P. Zdanevicius ◽  
R. Stonis ◽  
E. Spudulis ◽  
A. Koryakins ◽  
...  
Keyword(s):  
Heat Resistance ◽  
Thermal Shock ◽  
Quartz Sand ◽  
Metal Fiber ◽  
Cement Concrete ◽  
Heat Resistant ◽  
Heating And Cooling ◽  
Alkaline Resistance ◽  
Chamotte Concrete ◽  
Unilateral Heating

The article investigates the destruction of heat-resistant chamotte concrete of various classes: low-cement and medium-cement with the addition of quartz sand (to increase alkaline resistance) and with the addition of metal fiber (to reduce cracking) after exposure to thermal shock. Two methods for determining the heat resistance of concrete were used, in which the destruction of the material was evaluated using ultrasound using the method of a water-cooled plate and the method of one-sided heating-cooling. Studies conducted using the method of unilateral heating-cooling, revealed the formation of macrocracks in samples of low cement concrete. This method turned out to be more sensitive when evaluating concrete destruction.

Failure of Service Exposed Heat Resistant Cast Steel Tube

2018 ◽  
Vol 34 ◽  
pp. 1-4
Author(s):  
Meriem Aichaoui ◽  
Ali Hadji
Keyword(s):  
Cast Steel ◽  
Damage Mechanism ◽  
Mechanical Tests ◽  
Steel Tube ◽  
Localized Corrosion ◽  
Protective Oxide ◽  
Eutectic Carbides ◽  
Heat Resistant ◽  
Internal Working ◽  
Ammonia Plant

A heat resistant cast steel tube from an ammonia plant made of modified HP40 steel that failed after seven years of service was investigated for damage mechanism. The assessment of material degradation was carried out using optical microscopy, scanning electron microscopy (SEM) in combination with energy dispersive spectroscopy (EDS) analysis and mechanical tests. The main cause of failure appears to be overheating and localized corrosion along the network of intergranular carbides. Failed portion of the tube showed that the interdendritic eutectic carbides had coarsened, secondary carbides were precipitate and strongly coaresned within the austenitic regions. Witch decrease the mechanical strength and ductility of the service exposed tube compared with the as cast tube. Presence of unacceptable impurities like chlorine in the internal working gas destroy the protective oxide layer leading to penetration of corroding elements and degradation of service life of the tube.

scholarly journals EXPLOSIVE WELDING OF HEAT RESISTANT ALLOYS BASED ON REFRACTORY METALS WITH HIGH STRENGTH STEEL

2020 ◽  
pp. 87-91
Author(s):  
A. Yu. Malakhov ◽  
I. V. Saikov ◽  
I. V. Denisov
Keyword(s):  
High Strength Steel ◽  
Explosive Welding ◽  
High Strength ◽  
Weld Interface ◽  
Mechanical Tests ◽  
Explosion Welding ◽  
Heat Resistant Alloy ◽  
Steel Sheets ◽  
Heat Resistant ◽  
Strong Adhesion

In this work, the parameters of explosive welding of plates and pipes from heat resistant alloys with high-strength steel were established. It was found that to ensure strong adhesion, it is necessary to increase the kinetic energy of a flayer plate made of a heat-resistant alloy several times in comparison with the explosion welding of steel sheets. Metallographic studies have shown that at similar modes of explosion welding in cylindrical products, the number of cast inclusions is significantly increased compared to sheets up to the appearance of a continuous layer at the weld interface. Mechanical tests have confirmed the quality of the joint. This material is promising for work in structures experiencing thermal and erosive effects.

Structure-property relationships of PE/PP sandwiched films

1987 ◽  
Vol 45 ◽  
pp. 454-455
Author(s):  
J. Petermann ◽  
G. Broza ◽  
U. Rieck ◽  
A. Jaballah ◽  
A. Kawaguchi
Keyword(s):  
Mechanical Tests ◽  
Polymer Materials ◽  
Ionic Crystals ◽  
Structure Property ◽  
Polymer Systems ◽  
Structure Property Relationships ◽  
Oriented Films ◽  
Materials Used ◽  
Polymer Laminates ◽  
Heated Glass

Oriented overgrowth of polymer materials onto ionic crystals is well known and recently it was demonstrated that this epitaxial crystallisation can also occur in polymer/polymer systems, under certain conditions. The morphologies and the resulting physical properties of such systems will be presented, especially the influence of epitaxial interfaces on the adhesion of polymer laminates and the mechanical properties of epitaxially crystallized sandwiched layers.Materials used were polyethylene, PE, Lupolen 6021 DX (HDPE) and 1810 D (LDPE) from BASF AG; polypropylene, PP, (PPN) provided by Höchst AG and polybutene-1, PB-1, Vestolen BT from Chemische Werke Hüls. Thin oriented films were prepared according to the method of Petermann and Gohil, by winding up two different polymer films from two separately heated glass-plates simultaneously with the help of a motor driven cylinder. One double layer was used for TEM investigations, while about 1000 sandwiched layers were taken for mechanical tests.

Effect of silver nitrate on some mechanical properties of heat polymerizing acrylic resins

2019 ◽  
Vol 14 (1) ◽  
pp. 110
Author(s):  
Assiss. Prof. Dr. Sabiha Mahdi Mahdi ◽  
Dr. Firas Abd K. Abd K.
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Silver Nitrate ◽  
Surface Hardness ◽  
Mechanical Tests ◽  
Hardness Tester ◽  
Acrylic Resins ◽  
The Difference

Aim: The aimed study was to evaluate the influence of silver nitrate on surfacehardness and tensile strength of acrylic resins.Materials and methods: A total of 60 specimens were made from heat polymerizingresins. Two mechanical tests were utilized (surface hardness and tensile strength)and 4 experimental groups according to the concentration of silver nitrate used.The specimens without the use of silver nitrate were considered as control. Fortensile strength, all specimens were subjected to force till fracture. For surfacehardness, the specimens were tested via a durometer hardness tester. Allspecimens data were analyzed via ANOVA and Tukey tests.Results: The addition of silver nitrate to acrylic resins reduced significantly thetensile strength. Statistically, highly significant differences were found among allgroups (P≤0.001). Also, the difference between control and experimental groupswas highly significant (P≤0.001). For surface hardness, the silver nitrate improvedthe surface hardness of acrylics. Highly significant differences were statisticallyobserved between control and 900 ppm group (P≤0.001); and among all groups(P≤0.001)with exception that no significant differences between control and150ppm; and between 150ppm and 900ppm groups(P>0.05).Conclusion: The addition of silver nitrate to acrylics reduced significantly the tensilestrength and improved slightly the surface hardness.

Sign in / Sign up

Export Citation Format

Share Document