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For a reactor pressure vessel steel 15Kh2MFA(III) experiments and calculations have been carried out to study the factors that have an influence on the increase of the lower-shelf fracture toughness in the temperature dependence diagrams upon warm prestressing. Stereoscopic fractography and numerical investigation have demonstrated that after the warm prestressing the crack tip remains blunt. This reduces the stress singularity during subsequent loading and raises the material fracture toughness. The paper gives the calculated data on residual stresses and crack-tip opening displacement during warm prestressing and upon relief. The calculated results are shown to agree well with the known analytical relations and experimental data. [ABSTRACT FROM AUTHOR]

Increasing the operating temperature of industrial machinery requires compatible materials to the higher temperature, which will maintain their strength with desired properties. The marine, petrochemical, and aerospace industries involve contact of base alloys of industrial machinery and appliances with the environment consisting of oxygen and salts such as NaCl, Na2SO4, and V2O5. Thus, the substrate, i.e., superalloy, is coated with thermal barrier coatings (TBC) to protect the material from oxidation and hot corrosion. But due to wear-tear, intricate shapes, and designs, some parts of the substrate may be exposed to the environment. When the oxygen and salts react with the base alloy at high temperatures, it forms oxide products and corrosive salts. This may adversely affect the working of the industrial component. Thus, in the present study, Inconel 738 alloy specimens were coated with the salts NaCl, Na2SO4, and V2O5 in different combinations of proportions. The coated and not coated specimens were kept in the furnace for 500 h with a constant temperature maintained at 900°C. After this process, the specimens were tested on a slow strain rate testing machine (SSRT) for a low strain rate of 10–6 s–1. Scanning electron microscopy (SEM) was used to observe the fractured specimens to study the morphology of the fractured area. The elemental analysis was done by using electron dispersive spectroscopy (EDS). The X-ray diffraction (XRD) technique was used for analyzing the scale formed on the surface. [ABSTRACT FROM AUTHOR]

An experimental verification of the efficiency of the proposed method of taking into account the effect of time intervals under cycle maximum conditions on the low-cycle fatigue resistance of material has been obtained. Results of testing specimens of ZhS6KP alloy by the joint action of low-cycle and repeated static loading were used. [ABSTRACT FROM AUTHOR]

The authors consider the influence of temperature, load cycle asymmetry, specimen size, plastic prestraining, and material damage in the course of low-cycle loading on the magnitude of fatigue fracture toughness of heat resistant, high-strength chrome-molybdenum and other steels. They analyze the degree of this influence depending on various factors varied in the process of investigation. [ABSTRACT FROM AUTHOR]