Disappearance of the true threshold creep behaviour of an ODS Al–30SiCp composite at high temperatures

2000 ◽  
Vol 281 (1-2) ◽  
pp. 162-168 ◽  
Author(s):  
J. Čadek ◽  
K. Kuchařová ◽  
S.J. Zhu
Keyword(s):  
High Temperatures ◽  
Creep Behaviour ◽  
True Threshold

Investigations on Structure and High Temperature Properties of Iridium

2007 ◽  
Vol 539-543 ◽  
pp. 2216-2221 ◽  
Author(s):  
Jürgen Merker ◽  
Bernd Fischer ◽  
David F. Lupton ◽  
Joerg Witte
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
High Temperatures ◽  
Rupture Strength ◽  
Creep Behaviour ◽  
Stress Rupture ◽  
Service Performance ◽  
Metallographic Examination ◽  
Fine Grained ◽  
Pure Metals

Due to its outstanding mechanical properties at high temperatures and chemical stability iridium is used for demanding high temperature applications. In order to obtain materials data necessary for the design of high temperature equipment and the numerical simulation of their service performance the stress-rupture strength and creep behaviour have been investigated in a temperature range between 1650°C and 2300°C. The results of metallographic and fracture examinations (SEM) revealed that, in common with other pure metals, unalloyed iridium shows marked grain growth at high temperatures. Under these conditions, the deformation characteristics of iridium may not be entirely uniform and predictable, as will be demonstrated with examples from the creep studies. Both metallographic examination and investigations by means of scanning electron microscopy gave indications of possible causes for a significant anomaly in the creep behaviour. It is therefore advantageous for the mechanical properties if a fine-grained microstructure can be maintained even at the highest service temperatures.

Analysis of Creep Curves of Haynes 230 Superalloy

2010 ◽  
Vol 638-642 ◽  
pp. 2285-2290 ◽  
Author(s):  
Maurizio Maldini ◽  
Giuliano Angella ◽  
Valentino Lupinc
Keyword(s):  
Applied Stress ◽  
High Temperatures ◽  
Creep Curve ◽  
Creep Behaviour ◽  
Strong Dependence ◽  
Solution Treatment ◽  
Constant Load ◽  
Creep Tests ◽  
Haynes 230 ◽  
Creep Curves

The creep behaviour of the solid solution strengthened nickel-based superalloy Haynes 230 has been investigated under constant load and temperature conditions on as received, after conventional solution treatment, and on overaged conditions. The experimental results have shown a very strong dependence of the creep curve shape with the applied stress/temperature: in the tests performed at high stresses/low temperatures, the primary/decelerating stage takes an important portion of the creep curve. At these test conditions, the accelerating creep is mainly caused by the increase of the applied stress with the strain as it happens in constant load creep tests. In the tests performed at low stresses/high temperatures, the primary stage is very small and the following accelerating creep is characterized by different accelerating creep stages. The analysis of the creep curves on the as received and overaged alloys, has shown that a large portion of the accelerating creep at low stresses/high temperatures is caused by microstructural instability.

scholarly journals The effect of internal pressure and thickness on the creep strain of the superheater pipes

2020 ◽  
Vol 1 (1) ◽  
pp. 11-15
Author(s):  
Tri Widodo Besar Riyadi ◽  
Sopyan Sahid Fatuloh
Keyword(s):  
Internal Pressure ◽  
Creep Strain ◽  
High Temperatures ◽  
Creep Behaviour ◽  
Steam Superheater ◽  
The Finite Element Method ◽  
Materials Used ◽  
Thickness Variations ◽  
Temperature Loads ◽  
Creep Regime

Superheater pipes in turbines commonly are used to produce superheated steam. Internal pressure is critical for steam superheater elements. The pipes in such applications are vulnerable to temperature environments, which can bring the component to enter the creep regime, creep deformation, or even creep fracture. In general, most of the failures in boilers are caused by creep. Creep-resistant materials used in facilities operated at high temperatures must, therefore, be able to withstand the highest possible temperature loads. This study aims to investigate the creep behaviour of a 617 alloys steel steam pipe, which operated within 100,000 hours. The temperature of steam was set at 700?C, and the pressure in the pipe was 35 MPa. Abaqus software based on the finite element method was used in the study. The effect of internal pressure and pipe thickness on the creep strains was observed. The variation of the internal pressure was 35, 37.5, 40, 42.5, and 45 MPa. Whereas, the thickness variations were 30, 35, 40, 45, and 50 mm. The simulation results revealed that an increase in the internal pressure and the decrease of the pipe thickness increase the creep strain. This study can be used to predict the possibility of creep damaged for the superheater pipes operated at high temperatures, which have different thicknesses.

Creep Behaviour of a Thermoresistant Steel Working under Thermal Loads

2014 ◽  
Vol 601 ◽  
pp. 100-103
Author(s):  
Mihai Hluscu ◽  
Pavel Tripa
Keyword(s):  
High Temperatures ◽  
Creep Strength ◽  
Creep Behaviour ◽  
Thermal Loads ◽  
Creep Tests ◽  
Actual Problem ◽  
Methane Gas ◽  
Strength Variation

The estimation of the lifetime for equipments and installations working at high temperatures represent an actual problem. In the last years, there have been proposed a lot of methods in order to evaluate the lifetime for the equipments working under creep conditions. In the frameworks of the paper, some results regarding the behavior of pipes belonging to a methane gas cracking reactor are presented. Pipes worked on about 160.000 hours under a pressure of 14 at and a temperature of 800°C. The behavior of the pipes under above mentioned pressure has been calculated and plotted. Creep tests were performed at 650 and 800°C, and on these bases was evaluated the creep strength of the material. With Larson-Miller method the results were prolonged for spans shorter than 10.000 hours. The creep strength variation curves, drawn for 1000 and 100000 hours can be used for predictions about the lifetime at different.

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