Papers by Keyword: Weldments

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Authors: Qi Hua Xu, Qiang Xu, Yong Xin Pan, Michael Short
Abstract: This paper reports a critical summary of literature review of creep damage constitutive equations. Firstly, it introduces the general background on the creep damage in low alloy stainless steel and weldment. Then, it summarizes the typical creep damage constitutive equations for this material available from public literature and discusses the deficiencies existed in the popular creep damage constitutive equations. Finally it outlines the approach to be used in the developing a new set of creep damage constitutive equation and the directions of future work.
Authors: Joseph I. Achebo, A.O. Akii Ibhadode
Abstract: This work developed several welding flux compositions and came up with an optimum composition using the bending strength test technique. The technological performance of the optimum flux compositions with respect to the bend test was 230kN/m2. Preliminary weld tests showed that the flux performed well.
Authors: Zdeněk Kuboň
Abstract: Current trend in increasing steam parameters in ultra-supercritical (USC) boilers requires new materials not only for membrane walls, headers and pipelines but also for superheater and reheater tubes. Newly developed austentitic steels Super304H, TP347HFG and HR3C exhibit superior resistance in steam thanks to their fine-grained microstructure, especially in case of Super304H and TP347HFG. The paper presents the results of verification of properties of these steels tubes including creep resistance of the base metal and welded joints, which show promising level of long-term creep strength of the base metal and weld joints and these results are supplemented by some new knowledge about the development of the microstructure of these steels, especially sigma phase appearance.
Authors: Petr Brož
Abstract: It is explained which way a welded zone integrity has to concentrate on a number of inconveniences resulting from the weld behaviour. These problems will be discussed for evaluation of fatigue and fracture. Going after the fracture assessment address, the effect of weld configuration on stress intensity factor is fixing. A pertinent input to these methods is the limit load. In the view of the prominence of residual stresses in weldments, the interpretation of combined primary and secondary stresses in fracture evaluation is most desirable to be described in great detail. The influence of residual stresses on R – ratio is given. The weldment testing methods involve the techniques for definite microstructural regions and elimination of residual stress effects on fracture toughness measuring. For FCG rate predicting, the initial residual stresses are put into numerical models and residual stress distribution is simulated, incorporating crack growth. The technique is suggested for cracks initiating within a weld, namely in tensile residual stress zone.
Authors: Shan Tung Tu, Fu Zhen Xuan
Abstract: Current research efforts in the development of high temperature defect assessment procedure are summarized. Creep exemption criteria are proposed for the assessment of defective structures at high temperature in consideration of the effects of loadings, operating temperature and service time. Time-dependent failure assessment diagram (TDFAD) is developed that covers major failure mechanisms of defective high temperature structures. Challenges due to the welding effect are discussed. TDFAD for weldments is derived for various combinations of materials. In order to develop a unified assessment method to cope with material and loading complexity, a new failure assessment diagram based on continuum damage concept is proposed to reflect the damage effect on ductile creep failure and brittle creep fracture.
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