Influence of Stress State and Specimen Size on Creep Rupture of Similar and Dissimilar Welds

2009 ◽  
pp. 341-341-20 ◽  
Author(s):  
K Kussmaul ◽  
K Maile ◽  
W Eckert
Keyword(s):  
Stress State ◽  
Specimen Size ◽  
Creep Rupture ◽  
Dissimilar Welds

Isochronous creep rupture loci on deviatoric plane and its application to P92 steel creep behaviour under multiaxial stress state

2017 ◽  
Vol 35 (6) ◽  
pp. 513-522 ◽  
Author(s):  
Xiang Lan ◽  
Hong Xu ◽  
Mengyang Li ◽  
Yongzhong Ni ◽  
Peng Guo
Keyword(s):  
Stress State ◽  
Creep Behaviour ◽  
Creep Rupture ◽  
Multiaxial Stress ◽  
P92 Steel ◽  
Multiaxial Stress State ◽  
Deviatoric Plane

Modeling of the High Temperature Creep and Rupture under the Complex Stress State

2016 ◽  
Vol 870 ◽  
pp. 528-534 ◽  
Author(s):  
T.R. Stepanova ◽  
T.V. Prokhorova
Keyword(s):  
Experimental Data ◽  
Stress State ◽  
Damage Mechanics ◽  
Complex Stress ◽  
Complex Stress State ◽  
Creep Rupture ◽  
Creep Failure ◽  
Notched Specimens ◽  
Mechanics Model ◽  
Calculation Results

A damage mechanics model linked to the creep strain and stress three-axiality has been adopted to predict the creep lifetime under the complex stress state. The model accounts for primary-secondary-tertiary creep laws. Constitutive equation parameters were determined using experimental data of smooth specimens. Finite element modeling of creep rupture in notched specimens is presented in this work. The calculated creep failure strain and time to rupture for notched specimens (semicircular with radius 4.0 mm and U-notched with radius 1.2 mm) have been compared with experimental data for the X10CrMoVNb-9-1 steel tested at 625 °C. The calculation results of creep rupture for smooth and notched specimens show notch strengthening or notch weakening depending on the tensile stresses level and notch geometry.

scholarly journals Numerical Prediction of Creep Rupture Life of Ex-Service and As-Received Grade 91 Steel at 873 K

2021 ◽  
Vol 18 (3) ◽  
pp. 8845-8858
Author(s):  
IMAM UL FERDOUS ◽  
NASRUL AZUAN ALANG ◽  
Juliawati Alias ◽  
Suraya Mohd Nadzir
Keyword(s):  
Finite Element ◽  
Stress State ◽  
Creep Strain ◽  
Life Prediction ◽  
Rupture Life ◽  
Creep Rupture ◽  
Rupture Time ◽  
Damage State ◽  
Grade 91 ◽  
Grade 91 Steel

Infallible creep rupture life prediction of high  temperature steel needs long hours of robust  testing over a domain of stress and temperature. A substantial amount of effort has been made to  develop alternative methods to reduce the time  and cost of testing. This study presents a finite  element analysis coupled with a ductility based  damage model to predict creep rupture time  under the influence of multiaxial stress state of  ex-service and as-received Grade 91 steel at 873 K. Three notched bar samples with different  acuity ratios of 2.28, 3.0 and 4.56 are modelled in commercial Finite Element (FE) software,  ABAQUS v6.14 in order to induce different stress  state levels at notch throat area and investigate  its effect on rupture time. The strain-based  ductility exhaustion damage approach is  employed to quantify the damage state. The  multiaxial ductility of the material that is  required to determine the damage state is  estimated using triaxiality-ductility Cock and  Ashby relation. Further reduction of the ductility  due to the different creep mechanisms over a  short and long time is also accounted for in the  prediction. To simulate the different material conditions: ex-service and as-received material,  different creep coefficients (A) have been  assigned in the numerical modelling. In the case  of ex-service material, using mean best fit data  of minimum creep strain rate gives a good life  prediction, while for new material, the lower  bound creep coefficient should be employed to  yield a comparable result with experimental  data. It is also notable that ex-service material  deforms faster than as-received material at the  same stress level. Moreover, higher acuity  provokes damage to concentrate on the small  area around the notch, which initiates higher  rupture life expectancy. It also found out that,  the stress triaxiality and the equivalent creep  strain influence the location of damage initiation  around the notch area.

Fracture Behaviour of Mis-Matched Dissimilar Welds: Experimental Results

2002 ◽  
Author(s):  
Gre´goire Martin ◽  
Patrick Hornet ◽  
Mustafa Koc¸ak ◽  
Afshin K. Motarjemi
Keyword(s):  
Fracture Toughness ◽  
Stress State ◽  
Fracture Behaviour ◽  
Bonding Process ◽  
Material System ◽  
Single Edge ◽  
Dissimilar Welds ◽  
Nuclear Plants ◽  
Toughness Evaluation ◽  
Fracture Toughness Evaluation

In nuclear plants, ferritic-austenitic welded joints are commonly used. To better understand their fracture performances, EDF and GKSS have carried out a joint R&D project. In order to study the only influence of the strength mismatch and not of the Heat Affected Zone (HAZ), diffusion bonding process has been used. The characterization plan included numbers of tensile and fracture mechanics tests, on homogenous and bi-material specimens. Some Single Edge Notched Bending specimens (SENB) with the crack at different positions (that is to say in the ferrific side, austenitic side and finally at the interface) were used for the fracture toughness evaluation of the bi-material configuration. They showed the effect of strength mismatch relaxing the crack tip stress state at the interface. The paper will discuss in detail further features of the ductile and brittle fracture observed on this bi-material system.

Creep Rupture of Anisotropic Pipes

1998 ◽  
Vol 120 (3) ◽  
pp. 223-225 ◽  
Author(s):  
S. A. Shesterikov ◽  
A. M. Lokochtchenko ◽  
E. A. Mjakotin
Keyword(s):  
Experimental Data ◽  
Stress State ◽  
Anisotropic Material ◽  
Complex Stress ◽  
Complex Stress State ◽  
Creep Rupture ◽  
Suggested Method ◽  
Strength Anisotropy ◽  
Anisotropy Coefficient ◽  
Thin Walled

The problem of creep rupture of pipes from an anisotropic material is studied. The authors suggest a method describing the results of creep rupture tests on thin-walled pipes under complex stress state by taking the strength anisotropy of material into account. A coefficient of strength anisotropy has been determined from the results of creep rupture testing, and a method is given for calculation under various modes of complex stress state. This procedure is based on evaluating the values of the statistical spread from the experimental data. The anisotropy coefficient corresponding to the minimum spread is adopted. The suggested method of calculating the strength anisotropy coefficient is confirmed experimentally.

On the stress state dependence of creep rupture

1986 ◽  
Vol 34 (2) ◽  
pp. 243-256 ◽  
Author(s):  
V. Tvergaard
Keyword(s):  
Stress State ◽  
State Dependence ◽  
Creep Rupture ◽  
Stress State Dependence

Creep-Rupture Behavior of SUS 304H – IN 617 Dissimilar Metal Welds for AUSC Boiler Applications

2015 ◽  
Vol 830-831 ◽  
pp. 199-202
Author(s):  
A.H.V. Pavan ◽  
R. Ravibharath ◽  
Kulvir Singh
Keyword(s):  
High Temperature ◽  
Power Plants ◽  
Prolonged Exposure ◽  
Austenitic Stainless Steels ◽  
Creep Rupture ◽  
Advanced Materials ◽  
Thermodynamic Efficiency ◽  
Dissimilar Metal ◽  
Dissimilar Welds ◽  
Rupture Behavior

Advanced Ultra Super-Critical (AUSC) power plants are envisaged for achieving higher thermodynamic efficiency by operating at temperatures and pressures of 710/720 °C and 310 ata, respectively which are significantly higher than sub-critical (conventional) and supercritical power plants. This has led to tremendous research in selection of new and advanced materials to meet high temperature requirements. Ni-base superalloys having known to have excellent creep-rupture behavior were selected for high temperature sections of boiler while austenitic stainless steels were selected for moderately high temperature sections considering the economical feasibility. Since both these materials have to be fabricated for application in boiler tubes, dissimilar metal welding is inevitable. This work discusses creep-rupture evaluation of one such case of dissimilar welds, i.e., between Inconel 617 (IN 617) and SUS 304H. IN 617 is a Ni-base superalloy while SUS 304H is a Cu-precipitated austenitic stainless steel. Welding was carried out using IN 617 filler material for producing defect free welds. Creep-rupture samples were prepared incorporating the complete cross-weldment for understanding mechanical behavior as a result of prolonged exposure to elevated temperature and stresses. Creep-rupture testing was carried out at 600, 650 and 700°C at suitable stresses to obtain rupture times in the excess of 3000 hours in a few test conditions. Detailed characterization studies when carried out on ruptured samples revealed the weakest zone to be heat affected zone towards SUS 304H which led to failure. This work also provides insight into the possible creep-mechanisms that operate in various zones of weldments. Phases formed as a result of exposure to stress and temperature for a prolonged duration are also discussed. Comparison of the data obtained with data available in literature was carried out and performance of weldments was analyzed and reported.

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