The Rehbinder effect in tests of superalloys in contact with molten salts

The results of the Rehbinder effect manifestation during testing of superalloys in contact with corrosive media containing Na2SO4 + NaCl are discussed. We present the experimental study of the effect of salts containing chlorine and sulfur on the mechanical properties and long-term strength of single crystal and powder nickel-based superalloys at high temperatures. The practical value of the work is associated with the possible operation of gas turbine parts in conditions of ingress of the particles containing chlorine, sulfur and sodium into the flow path. A simplified (compared to a previously used) procedure of testing wrought alloys for long-term strength in molten salts is developed. A comparative study of the mechanical properties and long-term strength of a single crystal superalloy in the initial state (previously damaged by corrosion of different duration) and being in contact with salts during testing is carried out. Due to the large scatter of experimental data, the method of lower envelopes has been proposed and implemented to determine the guaranteed values of the long-term strength. It is shown that the guaranteed values of the long-term strength at different temperatures and test durations can decrease by 2.5 – 5.0 times in the presence of salts. Metallographic studies of the nature of damage and destruction of samples are carried out. The revealed decrease in the long-term strength of heat-resistant alloys in contact with salts is interpreted as the Rehbinder effect and not as a manifestation of the effect of stress corrosion cracking. A methodology for using the obtained test results with a duration of up to several thousand hours in highly aggressive environments is proposed to predict the long-term strength in relation to long-term operation (tens of thousands of hours) under conditions of relatively low salt loads.

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Long-Term Strength of a Composition of Complex Refractory Coating and Single-Crystal Rhenium-Alloyed Nickel Alloy after High-Temperature Holds

Metal Science and Heat Treatment ◽

10.1007/s11041-013-9644-2 ◽

2013 ◽

Vol 55 (7-8) ◽

pp. 403-408

Author(s):

V. P. Kuznetsov ◽

V. P. Lesnikov ◽

E. V. Moroz ◽

M. S. Khadyev ◽

I. P. Konakova

Keyword(s):

High Temperature ◽

Single Crystal ◽

Nickel Alloy ◽

Term Strength ◽

Refractory Coating ◽

Alloyed Nickel

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PROSPECTS FOR THE USE OF HOT ISOSTATIC PRESSING IN CAST ALUMINUM ALLOYS (review)

Proceedings of VIAM ◽

10.18577/2307-6046-2021-0-6-17-26 ◽

2021 ◽

pp. 17-26

Author(s):

E.A. Prokhorchuk ◽

◽

K.A. Vlasova ◽

A.V. Trapeznikov ◽

Yu.V. Reshetnikov ◽

...

Keyword(s):

Mechanical Properties ◽

Aluminum Alloys ◽

Hot Isostatic Pressing ◽

Term Strength ◽

Cast Aluminum ◽

Dense Structure ◽

Isostatic Pressing ◽

Cast Aluminum Alloys ◽

Strength Tests

The article provides an overview of studies on the influence of HIP on the density, roughness and mechanical properties of cast aluminum alloys. As a result of HIP, the density of the alloy, its ductility, and cyclic characteristics increase, and the scatter of mechanical properties determined during tensile and long-term strength tests decreases. The use of HIP increases the yield of good casting due to the reduction of rejects due to unacceptable porosity detected during х-ray inspection. Thus, the casting acquires a homogeneous, completely dense structure.

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Experimental Study on the Creep Behavior of Red Sandstone under Low Temperatures

Advances in Civil Engineering ◽

10.1155/2019/2328065 ◽

2019 ◽

Vol 2019 ◽

pp. 1-9 ◽

Cited By ~ 2

Author(s):

Yongjun Song ◽

Leitao Zhang ◽

Huimin Yang ◽

Jianxi Ren ◽

Yongxin Che

Keyword(s):

Mechanical Properties ◽

Low Temperature ◽

Deformation Characteristics ◽

Red Sandstone ◽

Rock Samples ◽

Uniaxial Creep ◽

Deformation Properties ◽

Accelerated Creep ◽

Different Temperatures

In cold regions, the deformation characteristics and long-term mechanical properties of rocks under low-temperature conditions are considerably different from those in other regions. To study the deformation characteristics and long-term mechanical properties of rocks in a low-temperature environment and the effect of different temperatures, we perform a multilevel loading-unloading uniaxial creep test on red sandstone samples and obtain the creep curves at different temperatures (20°C, −10°C, and −20°C). The results demonstrate that the total strain at each temperature can be divided into instantaneous and creep strains; the instantaneous strain includes instantaneous elastic and plastic strains, and the creep strain includes viscoelastic and viscoplastic strains. Temperature has a significant effect on the deformation properties of red sandstone. A decrease in temperature reduces the instantaneous and creep deformations of the rocks at all levels of stress. In addition, a decrease in temperature exponentially attenuates the total creep and viscoplastic strains of the rocks. 0°C is a critical point for the reduction of the total creep and viscoplastic strains of the rocks. When the temperature is greater than 0°C, the total creep and viscoplastic strains of the rocks decrease rapidly and linearly with decrease in temperature; however, when the temperature is less than 0°C, the decrease in the total creep and viscoplastic strains of the rocks is slow. The steady-state creep rate of the rock samples decreases with decrease in temperature, whereas the creep duration increases with decrease in temperature, especially in the case of the accelerated creep stage. The accelerated creep durations of the rock samples S4 (20°C) and S7 (–10°C) are 0.07 h and 0.23 h, respectively.

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Mechanical Properties of Gas Main Steels after Long-Term Operation and Peculiarities of Their Fracture Surface Morphology

Materials ◽

10.3390/ma12030491 ◽

2019 ◽

Vol 12 (3) ◽

pp. 491 ◽

Cited By ~ 6

Author(s):

Volodymyr Hutsaylyuk ◽

Pavlo Maruschak ◽

Ihor Konovalenko ◽

Sergey Panin ◽

Roman Bishchak ◽

...

Keyword(s):

Mechanical Properties ◽

Fracture Surface ◽

Damage Accumulation ◽

Classification Scheme ◽

Steel Structure ◽

Term Operation ◽

Gas Main ◽

Structure Degradation ◽

Main Pipelines

Regularities of steel structure degradation of the “Novopskov-Aksay-Mozdok” gas main pipelines (Nevinnomysskaya CS) as well as the “Gorky-Center” pipelines (Gavrilovskaya CS) were studied. The revealed peculiarities of their degradation after long-term operation are suggested to be treated as a particular case of the damage accumulation classification (scheme) proposed by prof. H.M. Nykyforchyn. It is shown that the fracture surface consists of sections of ductile separation and localized zones of micro-spalling. The presence of the latter testifies to the hydrogen-induced embrittlement effect. However, the steels under investigation possess sufficiently high levels of the mechanical properties required for their further safe exploitation, both in terms of durability and cracking resistance.

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Flip-Chip Ball Grid Array Lead-Free Solder Joint Under Reliability Test

Journal of Electronic Packaging ◽

10.1115/1.2070090 ◽

2005 ◽

Vol 127 (4) ◽

pp. 446-451 ◽

Cited By ~ 8

Author(s):

Ming-Hwa R. Jen ◽

Lee-Cheng Liu ◽

Jenq-Dah Wu

Keyword(s):

Mechanical Properties ◽

High Temperature ◽

Service Time ◽

Flip Chip ◽

Failure Modes ◽

Mechanical Responses ◽

Operational Life ◽

Different Temperatures ◽

Free Solder

The work is aimed to investigate the mechanical responses of bare dies of the combination of pure tin∕Al–NiV–Cu Under bump metallization (UBM) and packages of pure tin∕Al–NiV–Cu UBM/substrate of standard thickness of aurum. The mechanical properties under multiple reflow and long term high temperature storage test (HTST) tests at different temperatures and the operational life were obtained. A scanning electron microscope was used to observe the growth of IMC and the failure modes in order to realize their reaction and connection. From the empirical results of bare dies, the delamination between IMC and die was observed due to the tests at 260 °C multiple reflow. However, their mechanical properties were not affected. Nevertheless, the bump shear strength of bare dies were decreased by HTST tests. In package, all the results of mechanical properties by multiple reflow test and HTST test were significantly lowered. It was shown that the adhesion between bump and die reduced obviously as tests going on. As for high temperature operational life test in the conditions of 150 °C and 320 mA (5040A∕cm2), the average stable service time of the package was 892 h, and the average ultimate service time of the package was 1053 h.

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Degradation of mechanical properties of CrMoV and CrMoVW steam turbine rotors after long-term operation at elevated temperatures. Part I: tensile properties, intergranular fracture strength and impact tests

International Journal of Pressure Vessels and Piping ◽

10.1016/0308-0161(94)00044-1 ◽

1996 ◽

Vol 68 (1) ◽

pp. 99-111 ◽

Cited By ~ 5

Author(s):

M. Holzmann ◽

I. Dlouhý ◽

B. Vlach ◽

J. Krumpos

Keyword(s):

Mechanical Properties ◽

Steam Turbine ◽

Tensile Properties ◽

Intergranular Fracture ◽

Fracture Strength ◽

Elevated Temperatures ◽

Term Operation ◽

Impact Tests ◽

Degradation Of Mechanical Properties

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Determination of Actual Tensile and Fracture Characteristics of Critical Components of Industrial Plants Under Long Term Operation by SPT

Volume 6: Materials and Fabrication, Parts A and B ◽

10.1115/pvp2012-78553 ◽

2012 ◽

Cited By ~ 2

Author(s):

Karel Matocha

Keyword(s):

Mechanical Properties ◽

Residual Lifetime ◽

Test Technique ◽

Fracture Characteristics ◽

Industrial Plants ◽

Term Operation ◽

Critical Components ◽

Time Of Operation

The assessment of the residual lifetime of critical components of industrial plants requires the knowledge of mechanical properties prior to operation, respecting all technological operations realized throughout the manufacture of the component, and the knowledge of mechanical properties after actual time of operation (actual mechanical properties). Small Punch (SP) test technique enables measurement of the realistic material properties at the critical locations in the component both prior and after long-term operation. The paper shows the examples of the sampling of testing material from the critical components of the industrial plants and the procedures for determination of tensile and fracture characteristics by SP tests at ambient and low temperatures. The special attention is devoted to the test specimen orientation for determination of SP fracture energy ESP.

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Determination of Tensile Properties of Power Plant Steels by Testing of Miniature Specimens

Volume 6B: Materials and Fabrication ◽

10.1115/pvp2013-97135 ◽

2013 ◽

Cited By ~ 1

Author(s):

Ivan Klevtsov ◽

Andrei Dedov

Keyword(s):

Mechanical Properties ◽

Power Plant ◽

Flat Plate ◽

Tensile Properties ◽

Standard Size ◽

Term Operation ◽

University Of Technology ◽

Miniature Specimens

Long-term operation of the power plant components in the conditions of the creep leads to the degradation of the short-term mechanical properties of the material. Therefore, in order to predict the degree of the metal degradation and integrity of the component the determination of the mechanical properties of the actual component in service material is required. Since the standard tests requiring a significant volume of sample material cannot be applied the technique of the tensile testing of miniature flat plate specimens has been developed in Tallinn University of Technology and described in this paper. The results of the tests of miniature flat plate specimens have been compared with testing results of cylindrical specimens with standard size and at the same time the comparison has shown a good agreement of the results. The data analysis has also shown the high repeatability of the tests results of miniature specimens. Thus, the developed technique of the miniature flat plate specimens testing could be considered as accurate and reliable method and could be definitely used for evaluation of the tensile properties of the metal.

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