scholarly journals Effect of Hydrogen in Mixed Gases on the Mechanical Properties of Steels—Theoretical Background and Review of Test Results

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1847
Author(s):  
Thorsten Michler ◽  
Christian Elsässer ◽  
Ken Wackermann ◽  
Frank Schweizer
Keyword(s):  
Mechanical Properties ◽  
Test Methods ◽  
Theoretical Background ◽  
Special Focus ◽  
Pure Hydrogen ◽  
Test Results ◽  
Hydrogen Fugacity ◽  
Toughness Testing ◽  
Fatigue Crack Growth Testing ◽  
Mixed Gases

This review summarizes the thermodynamics of hydrogen (H2) in mixed gases of nitrogen (N2), methane (CH4) and natural gas, with a special focus on hydrogen fugacity. A compilation and interpretation of literature results for mechanical properties of steels as a function of hydrogen fugacity implies that test results obtained in gas mixtures and in pure hydrogen, both at the same fugacity, are equivalent. However, this needs to be verified experimentally. Among the test methods reviewed here, fatigue crack growth testing is the most sensitive method to measure hydrogen effects in pipeline steels followed by fracture toughness testing and tensile testing.

Application of Small Punch Test to Evaluate Tensile Properties of SA213T22 Grade Boiler Steel

2015 ◽  
Vol 830-831 ◽  
pp. 191-194
Author(s):  
M. Venkateswara Rao
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Tensile Properties ◽  
Test Methods ◽  
Uniaxial Tensile ◽  
Test Results ◽  
Small Punch Test ◽  
Small Punch ◽  
Punch Test ◽  
Aging Phenomena

Conventional tensile test methods are used for service exposed high temperature boiler tubes to evaluate the deterioration in mechanical properties such as tensile strength, yield strength and percentage elongation. The mechanical properties are required to be evaluated periodically as the boiler components undergo material degradation due to aging phenomena. The aging phenomena occurs due to continuous exposure of tubes to high temperature & pressure steam prevailing inside the tubes and high temperature exposure to corrosive combustible gases from the external surfaces within the boiler.A recent developed new technique called small punch testing has been used to evaluate the tensile properties of SA 213T22 grade steel predominantly exists in super-heater and re-heater sections of boiler. The small punch tests have been carried out on the miniature disk shaped specimens of diameter of 8.0 mm and 0.5 mm thickness extracted from both the new and service exposed tubes. Conventional uniaxial tensile tests on standard specimens from the same tube material have also been performed for comparison. The service exposed tubes showed considerable loss in mechanical properties in both the conventional and small punch test results. Correlations of tensile properties have been obtained based on the comparative analysis of both small punch and uniaxial tensile test results. Further, the study showed that an appropriate empirical relation could be generated for new and service exposed materials between both the techniques. Conventional test methods require large quantity of material removal for test samples from in-service components whereas small punch test method needs only a miniature sample extraction. This small punch test technique could also be extended to evaluate the thicker section boiler components such as pipelines and headers in the boiler as a part of remaining life assessment study. Also this technique could be a useful tool to any metallic component where large quantity of sample removal may be difficult or may not be feasible.

Re-Examining the Bulge Test: Methods for Improving Accuracy and Reliability

1991 ◽  
Vol 239 ◽  
Author(s):  
Martha K. Small ◽  
Joost J. Vlassak ◽  
William D. Nix
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Tensile Tests ◽  
Test Methods ◽  
Tension Test ◽  
Bulge Test ◽  
Test Results ◽  
Bulk Materials ◽  
Test Technique ◽  
Improving Accuracy

ABSTRACTSince its first application to thin films in the 1950's, the bulge test has had a prominent place in the field of thin film mechanical properties. The major appeal of the technique is that it is analogous to the familiar uniaxial tension test, which is commonly applied to bulk materials. At the same time, it avoids the sample tearing and alignment problems associated with micro-tensile tests. Unfortunately, bulge test results have been sometimes controversial and difficult to reproduce. In this paper we address possible causes for mese inconsistencies and describe a method by which the bulge test technique can be made to produce accurate and reliable results.

scholarly journals MINERALINIŲ MEDŽIAGŲ MECHANINIŲ SAVYBIŲ TYRIMAI, ANALIZĖ IR VERTINIMAS / RESEARCH, ANALYSIS, AND EVALUATION OF MECHANICAL PROPERTIES OF AGGREGATES

2018 ◽  
Vol 10 (0) ◽  
pp. 1-9 ◽  
Author(s):  
Lina Šneideraitienė ◽  
Daiva Žilionienė
Keyword(s):  
Mechanical Properties ◽  
Asphalt Pavement ◽  
Road Construction ◽  
Test Methods ◽  
Asphalt Mixtures ◽  
Test Results ◽  
Analysis And Evaluation ◽  
Baltic Countries ◽  
Research Analysis ◽  
Mineral Aggregates

The two Baltic countries, Lithuania and Latvia, use asphalt mixtures with granite slag that is imported from other countries to install the top layer of asphalt pavement, which is quite expensive. One of the requirements for aggregates used in road construction is mechanical properties. There are some differences between these countries based on national requirements. The article presents test methods for determining the mechanical properties of aggregates. According to them, the mechanical properties of aggregates were tested: resistance to fragmentation, wear, polishing and to wear by abrasion from studded tyre. Tested aggregates were Lithuanian dolomite quarry stone, which was made based on the developed and common technologies as well as imported granite from Ukraine. The analysis and evaluation of the test results have been carried out by the requirements for mineral aggregates of Lithuania and Latvia. Santrauka Dvi Baltijos šalys, Lietuva ir Latvija, asfalto dangos viršutiniam sluoksniui įrengti naudoja asfalto mišinius su granito skalda, kuri importuojama iš kitų šalių, o tai gana brangu. Vienas iš reikalavimų mineralinėms medžiagoms, naudojamoms kelių tiesyboje, yra mechaninės savybės. Jos minėtose šalyse pagal nacionalinius normatyvinius reikalavimus šiek tiek skiriasi. Straipsnyje pateikti mineralinių medžiagų mechaninių savybių nustatymo bandymo metodų aprašai. Pagal juos atlikti skaldų mechaninių savybių bandymai: atsparumas smūgiams, trupinimui, dėvėjimuisi, poliruojamumui (LST EN 1097-8:2009. Bandymai užpildų mechaninėms ir fizikinėms savybėms nustatyti. 8 dalis. Akmens poliruojamumo nustatymas) bei dygliuotoms padangoms. Ištirtos skaldos yra Lietuvos dolomito karjero skalda, pagaminta pagal patobulintą ir įprastą technologijas, bei granito skalda iš Ukrainos. Atlikta gautų bandymų rezultatų analizė bei vertinimas pagal Lietuvos ir Latvijos reikalavimus mineralinėms medžiagoms.

Some Observations on Rubber Testing

1934 ◽  
Vol 7 (1) ◽  
pp. 142-146
Author(s):  
J. R. Scott
Keyword(s):  
Mechanical Properties ◽  
Present Note ◽  
Test Methods ◽  
Present Writer ◽  
Published Data ◽  
Test Results ◽  
Insufficient Attention ◽  
Strontium Sulfate ◽  
The Subject ◽  
Selection Of

Abstract The subject of rubber testing and its standardization has received so much attention in recent years, that some apology might seem necessary for discussing it further. A few years ago the present writer had occasion to call attention to several respects in which existing test methods showed unnecessary lack of uniformity (Trans. Inst. Rubber Ind., 5, 139 (1929)), and it must be admitted that this lack of uniformity still persists to a great extent, with a corresponding loss in the value of published test results. It is the object of the present note to call attention more particularly to some unsatisfactory features in the selection of the “best” or “optimum” cure of a mix for purposes of comparison with other mixes. It is scarcely necessary to emphasize the fact that in comparing the properties of different mixings, as in examining the effects of fillers, accelerators, antioxidants, softeners, etc., all the mixings must be vulcanized to comparable states of cure. Nevertheless, an examination of published data shows that often insufficient attention is paid to ensuring strict comparability. For instance, it is not uncommon to find the effect of fillers examined by taking an accelerated base stock, adding the fillers to it, and vulcanizing all the resulting mixings for the same time, it being assumed that the fillers do not affect rate of cure. This assumption is not justifiable, even in the case of seemingly inert materials. An obvious case is that of gas black, which, though chemically inert, retards vulcanization in presence of organic accelerators. Moreover, such “inert” materials as barytes, blanc fixe, whiting, and strontium sulfate may markedly alter the rate of cure. Thus, in some experiments made by the writer, a base mix accelerated with dephenylguanidine (0.75% on the rubber) gave optimum mechanical properties after 90 minutes at 141° C., but mixings containing the fillers mentioned had optimum curing times ranging from 65 to 110 minutes. The writer has, indeed, come across a filler consisting of a very inert compound, which nevertheless completely puts out of action the most powerful organic accelerators. It is thus clearly unsafe to assume that any material will be inert as regards its effect on rate of vulcanization, whether in presence of an organic accelerator or not.

Static Compression Tests of Concentrated Crystallized Carbon Dioxide

2015 ◽  
Vol 816 ◽  
pp. 490-495 ◽  
Author(s):  
Jan Górecki ◽  
Ireneusz Malujda ◽  
Krzysztof Talaśka ◽  
Mateusz Kukla ◽  
Paweł Tarkowski
Keyword(s):  
Mechanical Properties ◽  
Carbon Dioxide ◽  
Test Methods ◽  
Test Results ◽  
Compression Tests ◽  
Static Compression ◽  
Starting Point ◽  
Ratio Limit ◽  
Limit Stress ◽  
The Relationship

This paper presents the results of static compression tests of concentrated crystallized carbon dioxide. The test results obtained under this research describe the relationship between the compressive stress and strain allowing to estimate the proportionality ratio, limit stress and critical stress values. Special test methods were used due to low temperature of crystallized carbon dioxide (minus 78.5°C) and its sublimation under standard testing conditions. The results of the mechanical properties of agglomerated CO2 were compared with the mechanical properties of other known materials. This allowed us to derive assumptions, which can become the starting point of the process to build a mathematical model describing the dry ice compaction and granulation processes.

Sunlight exposure: the effects on the performance of paragliding fabric

2018 ◽  
Vol 69 (05) ◽  
pp. 381-389
Author(s):  
MENGÜÇ GAMZE SÜPÜREN ◽  
TEMEL EMRAH ◽  
BOZDOĞAN FARUK
Keyword(s):  
Mechanical Properties ◽  
Aging Process ◽  
Air Permeability ◽  
Sunlight Exposure ◽  
Test Results ◽  
Coating Materials ◽  
Strength Tests ◽  
Before And After ◽  
The Relationship ◽  
Dark Blue

This study was designed to explore the relationship between sunlight exposure and the mechanical properties of paragliding fabrics which have different colors, densities, yarn counts, and coating materials. This study exposed 5 different colors of paragliding fabrics (red, turquoise, dark blue, orange, and white) to intense sunlight for 150 hours during the summer from 9:00 a.m. to 3:00 p.m. for 5 days a week for 5 weeks. Before and after the UV radiation aging process, the air permeability, tensile strength, tear strength, and bursting strength tests were performed. Test results were also evaluated using statistical methods. According to the results, the fading of the turquoise fabric was found to be the highest among the studied fabrics. It was determined that there is a significant decrease in the mechanical properties of the fabrics after sunlight exposure. After aging, the fabrics become considerably weaker in the case of mechanical properties due to the degradation in both the dyestuff and macromolecular structure of the fiber

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