... of localized hot spots, creep microvoids, and spheroidization of carbides. In addition, a thickness reduction of 18% resulted in a considerable increase in hoop stresses having a detrimental effect on the remaining creep life. To explain the creep damage mechanism and determine the remaining creep life...

...Markian Petkov; George A. Young; Pierre-Alexandre Juan Future Gen IV high-temperature reactors are expected to operate above 450 °C where creep effects are significant in safety-related structures, e.g., reactor vessels. The ASME Boiler and Pressure Vessel Code (BPVC) Section III Division 5...

... is loftier. It questions the fundamental premise of power law and offers an alternative method to obtain meaningful stationary stress states. It lays the foundation for doing better creep analysis if incorporated into prevailing techniques such as the Linear Matching Method [ 7 ]. For the first time it has...

... the potential to be woven into LMM to address creep problems, but at this stage, we limit ourselves to arriving at stationary stress states that are more meaningful than those offered by the power law. Sections 4 – 8 consider a few typical cases to illustrate the robustness of Eq. (4) . Fig. 6 Typical...

... temperature that causes degradation of material properties. Pressure reducing valve is an important component being employed within a main steam line of the supercritical boiler, which occasionally thermal-fatigue failure being reported. This research has investigated creep-cyclic plastic behavior...

... accident. The materials used previously for SG tubes around the world have been replaced and will be replaced by Alloy 690 given its improved corrosion resistance relative to that of Alloy 600. However, studies of the high-temperature creep and creep-rupture characteristics of SG tubes made of Alloy 690...

...Cheng Gong; Fu-Hai Gao; Jian-Guo Gong; Fu-Zhen Xuan An accurate stress estimation for creep evaluation is essential for the long-term safe operation of components at elevated temperature. In general, the section-dependent parameter K t is defined in elastic analysis routine to account...

...Tian-Ye Niu; Cheng Gong; Jian-Guo Gong; Fu-Zhen Xuan Notched structures widely exist in steam turbine components in fossil power plant, e.g., the groove of the rotor, etc. Previous studies indicate that creep failures occur at the groove of the rotor or the adjacent regions. Thus, it is essential...

...Tian-Ye Niu; Cheng Gong; Jian-Guo Gong; Fu-Zhen Xuan; Haofeng Chen Geometrical discontinuities (such as holes and grooves) widely exist in many components, which operate at elevated temperatures. Creep assessment of the geometrical discontinuities is essential for the safe operation of the system...

...Lin Zhu; Xinbao Liu; Ping Fan; Jianqiu Liu; Chengfei Pan Over the range of variables (temperature and stress) normally encountered in service applications, creep behaviors of 9Cr-1Mo steel were investigated with various models, such as Wilshire model, combination of exponential form and omega (CEO...

... in standardized relaxation tests. Within this work, a loss in bolt pretension of up to almost 50% over a comparatively short period of experimental time was observed. By means of numerical calculations, creep deformation in the transition areas between pipe and flange plate sections was identified to be a major...

... on the structural strength of the notched components at elevated temperatures under creep, fatigue, and creep-fatigue loading conditions. Experimental phenomena (i.e., strengthening or weakening effects) for typical notched specimens subjected to the above three loading conditions are summarized, and the related...

... internally (∼1327 °C), it results in a sudden transition of boiling crisis from nucleate to film boiling. Accordingly, from a structural integrity perspective, the RPV failure mechanisms span a wide range of structural behaviors, such as melt-through, creep damage, plastic deformation as well as thermal...

... is the increment of plastic or creep strain that occurs at time t n . Thus the minimization function in an incremental form is written as (6) I n ( Δ ɛ ij n ) = ∫ V { σ ij n Δ ɛ ij n - [ σ ∧ ij ( t n ) + ρ...

... April 16, 2014. Assoc. Editor: Marina Ruggles-Wrenn. 11 09 2013 24 01 2014 Centrifugal cast 25Cr35Ni–Nb alloy furnace tubes with different contents of S are selected to investigate effects of S addition on creep and fracture behavior. Rupture tests in air at 1100 °C and 17 MPa...

... ) - exp ( ɛ θ ' ) ] 2 ( d / r o ) 2 + [ exp ( ɛ θ ) - exp ( ɛ θ ' ) ] 2 The total true strain in each direction is thought to be the sum of elastic strain, plastic strain, thermal strain and creep, i.e., (21) ɛ...

...Charles Becht, IV; Charles Becht, V A number of alloys have applications slightly into the creep range that are in cyclic service, such as process reactors. The 2007 edition of Section VIII, Division 2 (2007, ASME Boiler and Pressure Vessel Code, Section VIII, Division 2, The American Society...

...Basil A. Housari; Ali A. Alkelani; Sayed A. Nassar An improved mathematical model is proposed for predicting clamp load loss due gasket creep relaxation in bolted joints, taking into consideration gasket behavior, bolt stiffness, and joint stiffness. The gasket creep relaxation behavior...

... contact stress at gasket outer diameter in consideration of creeps of flanges, bolts and gasket coupled to the axial deformation compatibility equation. The analysis was verified against the finite element numerical simulation considering the nonlinear behavior of gasket and material creep. The analytical...

... to investigate the statistical variation for the anisotropic materials in strain rate effect problem and creep strain program by introducing additional six cubic slip systems into the conventional 12 octahedral slip systems inelastic range. anisotropic media creep finite element analysis grain size...