scholarly journals Microstructural Evolution and Short-Term Creep Rupture of the Simulated HAZ in T92 Steel Normalized at Different Temperatures

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1310 ◽  
Author(s):  
Tai-Jung Wu ◽  
Chien-Chun Liao ◽  
Tai-Cheng Chen ◽  
Ren-Kae Shiue ◽  
Leu-Wen Tsay
Keyword(s):  
Grain Boundaries ◽  
Elevated Temperatures ◽  
Creep Rupture ◽  
Infrared Heating ◽  
Short Term ◽  
Creep Tests ◽  
Steel Tubes ◽  
Austenite Grain ◽  
Term Creep ◽  
Short Term Creep

T92 steel tubes have been widely applied in advanced supercritical boilers to replace Gr.91 tubes. Simulated samples with microstructures similar to those present in the heat-affected zone (HAZ) of a T92 steel weld were subjected to short-term creep tests in the study. T92 steel tubes were normalized at either 1213 K (L) or 1333 K (H) for 1 h, followed by tempering (T) at 1033 K for 2 h. After the normalizing and tempering treatments, the HT samples comprised finer precipitates but in greater numbers along the prior austenite grain boundaries (PAGBs) and martensite lath boundaries, as compared with those of the LT samples. The HAZ microstructures in the T92 steel welds were simulated by using an infrared heating system, which included over-tempering (OT, below AC1) and partial transformation (PT, slightly below AC3) zones. Martensite laths in the OT sample were more likely to be replaced by numerous cellular structures or subgrains together with spherodized carbides mainly located at the lath and austenite grain boundaries. Furthermore, coarser but fewer carbides were found along the refined lath and grain boundaries in the PT samples, in comparison with other samples in each group. Short-term creep tests showed that the PT samples were more likely to fracture than other samples in each group. Moreover, under the same testing conditions, the microstructures of T92 steel were more stable and resistant to degradation than those of T91 steel after welding or loading at elevated temperatures. Such events were responsible for higher creep resistance of the simulated T92 samples than that of the simulated T91 samples under the same creep-rupture conditions.

scholarly journals The Effect of Normalizing Temperature on the Short-Term Creep Rupture of the Simulated HAZ in Gr.91 Steel Welds

Metals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 1072 ◽  
Author(s):  
Hao-Wei Wu ◽  
Tai-Jung Wu ◽  
Ren-Kae Shiue ◽  
Leu-Wen Tsay
Keyword(s):  
Creep Resistance ◽  
Lath Martensite ◽  
Heating System ◽  
Steel Tube ◽  
Infrared Heating ◽  
Short Term ◽  
Creep Tests ◽  
Steel Welds ◽  
Term Creep ◽  
Short Term Creep

As-received Gr.91 steel tube was normalized at either 940 or 1060 °C for 1 h, followed by Ar-assisted cooling to room temperature, then tempered at 760 °C for 2 h. Those samples were designated as 940NT or 1060NT samples. An infrared heating system was used to simulate HAZ microstructures in the weld, which included over-tempering (OT) and partial transformation (PT) zones. The results of short-term creep tests showed that normalizing at higher temperature improved the creep resistance of the Gr.91 steel. By contrast, welding thermal cycles would shorten the creep life of the Gr.91 steel. Among the tested samples in each group, the PT samples had the shortest life to rupture, especially the 940NT-PT sample. The microstructures of the PT samples comprised of fine lath martensite and ferrite subgrains with carbides decorating the grain and subgrain boundaries. Excessive dislocation recovery, rapid coalescence of refined martensite laths, and growth of ferrite subgrains were responsible for the poorer creep resistance of the PT samples relative to those of the other samples.

Predicting Collapse Times for Corrugated Boxes Under Constant Top Load Using Short-Term Creep Tests

2005 ◽  
Vol 33 (4) ◽  
pp. 11932
Author(s):  
DR Petersen ◽  
RE Link ◽  
G Burgess ◽  
SP Singh ◽  
M Srinangyam
Keyword(s):  
Short Term ◽  
Creep Tests ◽  
Term Creep ◽  
Short Term Creep

scholarly journals Microstructural Evolution of X20CrMoV12.1 Steel upon Short-term Creep Rupture Test

2013 ◽  
Vol 43 (4) ◽  
pp. 164-172 ◽  
Author(s):  
Mariko Hino ◽  
Yinsheng He ◽  
Kejian Li ◽  
Jungchel Chang ◽  
Keesam Shin
Keyword(s):  
Microstructural Evolution ◽  
Creep Rupture ◽  
Short Term ◽  
Creep Rupture Test ◽  
Term Creep ◽  
Short Term Creep

Evaluation of Short Term Creep-Rupture Strength of High Temperature P122 Boiler Material

2003 ◽  
Author(s):  
John Pumwa
Keyword(s):  
High Temperature ◽  
Fracture Mode ◽  
Life Prediction ◽  
Rupture Strength ◽  
Creep Rupture ◽  
Creep Rupture Strength ◽  
Short Term ◽  
Boiler Material ◽  
Term Creep ◽  
Short Term Creep

The complex thermal-mechanical loading of power-generating plant components usually comprises of creep, high-cycle and low-cycle fatigue which are thermally induced by start-ups, load changes and shut-downs, producing instationary temperature gradients and hence creating strain as well as stress fields. In order to select the correct materials for these hostile environmental conditions, it is vitally important to understand the behaviour of mechanical properties such as creep rupture properties of these materials. This paper reports the results of standard creep rupture tests of P122 (HCM12A or 12Cr-1.8W-1.5Cu) high temperature boiler material. P122 is one of the latest developed materials for high temperature environments, which has the potential to be successful in hostile environments. The tests were conducted at temperatures ranging from 550°C to 700°C at 50°C intervals with stress levels ranging from 80–400 MPa using a locally made creep rupture testing machine. The results are found to have stable creep-rupture strength at short term creep stage for over 800-hours at elevated temperatures. Creep life prediction from Larson-Miller relationship was also carried out and the accuracy of life prediction is demonstrated. Moreover, the fracture mode assessments strongly revealed a typical ductile transgranular fracture mode with dimples and voids.

scholarly journals Time-temperature behavior of carbon/epoxy laminates under creep loading

2020 ◽  
Author(s):  
Heitor L. Ornaghi ◽  
José Humberto S. Almeida ◽  
Francisco M. Monticeli ◽  
Roberta M. Neves ◽  
Maria Odila H. Cioffi
Keyword(s):  
Composite Laminates ◽  
Material Behavior ◽  
Short Term ◽  
Creep Tests ◽  
Advanced Composite ◽  
Wide Range ◽  
Temperature Superposition ◽  
Term Creep ◽  
Creep Loading ◽  
Short Term Creep

Abstract The time-temperature creep behavior of advanced composite laminates is herein determined through a comprehensive set of experiments and analytical modeling. A complete structure versus property relationship is determined through a wide range of temperature and applied stress levels at the three states of the composite: glassy, glass transition, and rubbery regions. Weibull, Eyring, Burger, and Findley models are employed to predict the experimental data and to better elucidate the material behavior. Experimental creep tests are carried out under ten min and two days aiming at calibrating fitting parameters, which are essential to validate short-term creep tests. The Weibull and Eyring models are more suitable for determining the time-temperature superposition (TTS) creep response in comparison to the Burger and Findley models.

scholarly journals Creep Behaviour of Modified Mar-247 Superalloy

2016 ◽  
Vol 61 (2) ◽  
pp. 701-704 ◽  
Author(s):  
M. Cieśla ◽  
M. Mańka ◽  
F. Binczyk ◽  
P. Gradoń
Keyword(s):  
Creep Behaviour ◽  
Rupture Life ◽  
Coarse Grained ◽  
Short Term ◽  
Creep Tests ◽  
Nickel Based Superalloy ◽  
Test Conditions ◽  
Accelerated Creep ◽  
Term Creep ◽  
Short Term Creep

Abstract The paper presents the results of analysis of creep behaviour in short term creep tests of cast MAR-247 nickel-based superalloy samples made using various modification techniques and heat treatment. The accelerated creep tests were performed under temperature of 982 °C and the axial stresses of σ = 150 MPa (variant I) and 200 MPa (variant II). The creep behaviour was analysed based on: creep durability (creep rupture life), steady-state creep rate and morphological parameters of macro- and microstructure. It was observed that the grain size determines the creep durability in case of test conditions used in variant I, durability of coarse-grained samples was significantly higher.

Research on Rheological Properties of Room-Temperature Curing Epoxy Adhesive

2013 ◽  
Vol 639-640 ◽  
pp. 354-358 ◽  
Author(s):  
Hui Li ◽  
Ying She Luo ◽  
Jian Jun Xie ◽  
Sheng Ming Chen
Keyword(s):  
Mechanical Properties ◽  
Rheological Model ◽  
Room Temperature ◽  
Epoxy Adhesive ◽  
Test Results ◽  
Short Term ◽  
Creep Tests ◽  
C 30 ◽  
Term Creep ◽  
Short Term Creep

The rheological mechanical properties of two kinds of self-designed epoxy adhesive curing systems were studied in this paper through the dynamic and static thermodynamics instrument named EPLEXOR 500N made by GABO® company in Germany. Short-term creep tests were carried out under three different temperature conditions of 20°C, 30°C and 40°C and the rheological model is developed to describe the materials creep law. In addition, the test results from the two different epoxy adhesive are also compared and analyzed.

Evaluation of Short-term Creep Behavior of PE-HD after Aging in Oil Derivatives

2018 ◽  
Vol 26 (3) ◽  
pp. 243-250 ◽  
Author(s):  
Ayrton Alef Castanheira Pereira ◽  
José Roberto Moraes d'Almeida ◽  
Thiago Motta Linhares Castro
Keyword(s):  
Creep Behavior ◽  
Diesel Oil ◽  
Aging Effects ◽  
Short Term ◽  
Creep Tests ◽  
Before And After ◽  
Oil Derivatives ◽  
Term Creep ◽  
Effects Of Aging ◽  
Short Term Creep

The creep behavior of a high density polyethylene (PE-HD) was evaluated before and after aging in contact with gasoline and diesel oil. Four viscoelastic models were used to assess changes in creep properties of the material: three parameters model, four parameters model, stretched Burgers model and Findley Law. Viscoelastic properties, stationary creep rate and compliance were used to analyze and compare the behavior between samples. A strain increase could be seen in aged samples in comparison with as-received ones, caused by plasticization due to aging effects. An increase in flexibility and decrease in stiffness in aged samples was also noted. This work also shows that the effects of aging on the creep response of a polymeric material can be analyzed using short term creep tests.

Modeling of a Long-Term Creep Curve of Alloy 617 for a High Temperature Gas-Cooled Reactor

2008 ◽  
Vol 385-387 ◽  
pp. 693-696 ◽  
Author(s):  
Woo Gon Kim ◽  
Song Nan Yin ◽  
Ik Hee Jung ◽  
Yong Wan Kim
Keyword(s):  
Least Square ◽  
Short Term ◽  
Creep Tests ◽  
Least Square Fitting ◽  
Creep Curves ◽  
Term Creep ◽  
Good Agreement ◽  
Short Term Creep ◽  
Stress Dependency

This study aimed to model the long-term creep curves above 105 hours by implementing a nonlinear least square fitting (NLSF) of the Kachanov-Rabotnov (K-R) model. For this purpose, the short-term creep curves obtained from a series of creep tests at 950oC were used. In the NLSF of their full creep curves, the K-R model represented a poor match to the experimental curves, but the modified K-R one revealed a good agreement to them. The Monkman-Grant (M-G) strain represented the behavior of a stress dependency, but the 􀁏 parameter was constant with a stress independency. The 􀁏 value in the modified K-R model was 2.78. Long-term creep curves above 105 hours from short-term creep data were modeled by the modified K-R model.

Sign in / Sign up

Export Citation Format

Share Document