Influence of temperature and exploitation period on the behaviour of a welded joint subjected to impact loading

Presented in this paper is the analysis of the influence of temperature and exploitation period on the measure of fracture resistance of welded joint constituents in both new and exploited low-alloyed Cr-Mo steel A-387 Gr. B subjected to impact load. Exploited parent material was a part of the reactor mantle in exploitation for over 40 years and is currently in the repair stage, wherein a part of the mantle is being replaced with newly built-in material. Performed are impact tests of a notched specimen of new and exploited parent material (PM), weld metal (WM) and heat affected zone (HAZ), at both the exploited and new PM sides, in order to determine total impact energy, and its components, crack initiation-and crack propagation energy. Based on test results, analysis of tendency toward brittle fracture, i.e. toward an increase of in-service brittleness (ageing) represents the comparison of values obtained for characteristic areas of welded joints and the justification of the selected welding technology

Influence of temperature and exploitation period on the behaviour of a welded joint subjected to impact loading

Presented in this paper is the analysis of the influence of temperature and exploitation period on the measure of fracture resistance of welded joint constituents in both new and exploited low-alloyed Cr-Mo steel A-387 Gr. B subjected to impact load. Exploited parent material was a part of the reactor mantle in exploitation for over 40 years and is currently in the repair stage, wherein a part of the mantle is being replaced with newly built-in material. Performed are impact tests of a notched specimen of new and exploited parent material (PM), weld metal (WM) and heat affected zone (HAZ), at both the exploited and new PM sides, in order to determine total impact energy, and its components, crack initiation-and crack propagation energy. Based on test results, analysis of tendency toward brittle fracture, i.e. toward an increase of in-service brittleness (ageing) represents the comparison of values obtained for characteristic areas of welded joints and the justification of the selected welding technology

Numerical Simulation of Fatigue Crack Growth in Different Welded Joint Zones

This paper involves the numerical analysis of fatigue behaviour of welded joints made of steel SA-387 Gr. 91, with special attention devoted to its regions, which have very different mechanical and fatigue properties. Extensive experimental research, which was performed in order to obtain the coefficients necessary for the analysis of fatigue life of structures and parts made of this steel, was used as the base for the finite element method simulation, performed in ANSYS R19.2. Due to the typical applications of steels from this group, all experiments were performed at elevated temperature of 575 °C, which corresponds to the exploitation conditions for this material. Obtained results have shown noticeable difference in fatigue crack growth resistance of different welded joint regions, as was expected from the experimental results

The influence of the temperature and exploitation time on the behaviour of a welded joint subjected to variable and impact load

This paper presents the analysis of the temperature and exploitation time influence on the resistant measure to brittle fracture of welded joint constituents of the new and exploited low-alloyed Cr-Mo steel A-387 Gr. B subjected to variable and impact load. The exploited parent metal is a part of the reactor mantle which has been exploited for over 40 years and is in the damage repair stage. Wohler’s curves are constructed, that is, fatigue strength as the resistance of the material to the crack initiation and the total impact energy, as well as the components, crack initiation energy and crack propagation energy at room and working energy are determined. Based on the research results, the analysis of the resistance to brittle fracture represents the comparison of obtained values for characteristic areas of welded joint and justification of the selected welding technolog

Effect of material heterogeneity and testing temperature on fatigue behaviour of Cr-Mo steel welded joints

Successful application of Cr-Mo steel depends crucially on behaviour of all zones in welded joints, i.e. base metal (BM), heat-affected-zone (HAZ) and weld metal (WM), both at room and working temperature. Different amplitude loadings were applied for testing of specimens without a crack, made of welded joint as a whole and of BM, in order to obtain Woehler's curves and compare their dynamic strength. Amplitude loading was also applied for testing of specimens cracked in BM, HAZ and WM, in order to get fatigue crack growth curves and parameters C and m in Paris law. Results are analysed to get deeper insight into behaviour of welded joints, made of steel SA 387 Gr. 91, under amplitude loading both for room and working temperature

Examination of wear resistance of polymer-basalt composites

Olivine basalt, as a natural material, has excellent physical and mechanical properties such as hardness, compressive strength, wear resistance, color and gloss. On the other hand it is difficult for processing, because of its high values of mechanical properties. Retention of physical and mechanical properties of basalt and its formation is only possible by mixing basalt powder with polymers, which would enable the composite material that can be formed by the casting process into complex shapes. The mechanical properties of the obtained composites and production technologies are, to a great extent, unknown in both, local and foreign literature. Researches conducted and presented in this paper show an overview of tribological behavior of the basaltic composite material, and some technological parameters of the production process. Based on the obtained results, it can be determine the best ratio of components in the composite. These data are important for the development of new composite materials based on basalt, which will have significant application in the future

Structural integrity and life assessment of pressure vessels - risk based approach

Risk based approach to assess structural integrity and life of pressure vessel has been presented, starring from EU PED 2014/68 and API 581, ending with use of basic fracture mechanics parameters. In the scope of risk matrix, structural integrity has been tackled by use of the Failure Assessment Diagram (FAD), while structural life was assessed by means of Paris law, using fatigue crack growth rate as relevant parameter. Several case studies have been provided to illustrate this comprehensive approach, including penstock and air storage tanks in Reversable Hydro Power Plant, and two spherical storage tanks, one for vinyl chloride monomer (VCM), the other for ammonia. Besides the assessment of integrity and life, including some important issue like over-pressurizing, roles of engineers and managers in this process is defined and explained