Fatigue life prediction of structural steel using acoustic birefringence and characteristics of persistent slip bands

Nondestructive evaluation methods provide additional information about the material fatigue behavior and enhance the comprehension of damage evolution thanks to relationship between microstructure and physical properties. This paper deals with optical and ultrasonic investigations of structural steel specimens tested for low-cycle fatigue. The development of persistent slip bands observed on the surface with an optical microscope was quantified using a previously trained neural network and fractal analysis. A surface damage parameter was defined as the ratio of total area of detected slip bands to the area of observed surface. Relationships between the rate of change and critical value of the damage parameter, the strain range, and the fatigue life were established. A single square relationship between relative number of cycles and ratio of the surface damage parameter to its critical value was obtained. Acoustic birefringence was measured by the echo method. The effect of the strain range on the rate of change in acoustic birefringence was investigated. A single linear relationship between relative number of cycles and change in acoustic birefringence was established. An algorithm for predicting the material remaining life, combining optical and ultrasonic data, was proposed.     

Study of Copper and Zinc Extraction from Underspoil Water

Metallurgist - The subject of study was the Safyanovskaya Med company’s acidic underspoil water containing 0.17 g/liter of copper and 1.8 g/liter of zinc (pH 2.8–2.9). The goal was to...     

Recovery of nickel from hydrate pulps at amino carboxylic cationites

Regularities of the sorption of nickel from hydrate pulps using amino carboxylic cationites ANKB-35, S 930, and TP 207 are investigated. Kinetic curves and sorption isotherms for these cationites are constructed. It is revealed that it is reasonable to absorb nickel from pulps at pH = 4–5. The desorption of nickel from cationites is investigated. It is shown that cationite TP 207 possesses the maximal sorption capacity.     

Concentrating Nickel from Leaching Solutions for Oxidized Nickel Ore Based on Precipitation of Hydrates

The article focuses on concentrating of nickel from lean solutions of leaching of oxidized nickel ore. The proposed block diagram of process flow chart for such solutions includes hydrolytic removal of admixed iron and aluminium and precipitation of nickel concentrate by calcinated magnesia. As a result, nickel content of the concentrate is 26–26% at the recovery of 95–97%. The issues of decontamination and recycling of the solutions are solved.     

Modeling of Exchange Interactions in Melts Formed During Joint Smelting of Oxidized Nickel Ores and Pyrrhotite Concentrates

Metallurgist - An original methodology based on the use of experimental values of the conditional equilibrium constants in metallurgical calculations was employed to perform a theoretical modeling...     

Application of Sulfide Copper Ores Oxidizing Roasting Products as Sulfidizing Agent During Melting Nickel Raw Materials To Matte

Metallurgist - X-ray fluorescence analysis, X-ray powder diffraction, electron microprobe analysis, scanning electron microscopy, and thermal analysis are used to evaluate the material composition,...     

Ultrasonic and Eddy-Current Fatigue Monitoring of Austenitic Steel Welded Joints

Russian Journal of Nondestructive Testing - We investigated the process of fatigue damage in welded joints made of austenitic steel by ultrasonic and eddy current types of testing. The development...     

Erratum to: Ultrasonic and Eddy-Current Fatigue Monitoring of Austenitic Steel Welded Joints

Russian Journal of Nondestructive Testing - An Erratum to this paper has been published: https://doi.org/10.1134/S1061830921090126     

Kinetic features of underground uranium leaching from ores of hydrogenous uranium deposits

The dependence of the rate of uranium leaching from ores of hydrogenous deposits on the temperature and reagent concentrations was examined. The limiting step of the process was found from the calculated apparent activation energy and apparent reaction order. Ways to intensify underground uranium leaching were outlined.     

Sulphuric-Acid Leaching of Ural Oxidized Nickel Ore with Sodium Sulfite and Fluoride Additives

The process of leaching oxidized nickel ore in sulphuric acid with the additives of sodium sulfite and fluoride is investigated. Tochilnogorsky deposit ore (Sverdlovsk Region) is used to prove theoretically and experimentally efficient application of fluoride in dissociation of nickel minerals (nontronite and garnierite) in oxidized nickel ore. It is shown that at NaF consumption of 10 kg/t, it is possible to enhance maximum extraction of nickel to solution from 82.3–86.9 to 96.0–98.7% at the residual sulphuric acid concentration of 10–20 g/l in the working bath. It is found that the sodium fluoride additives lower the process activation energy from 22.8 to 12.9 kJ/mole. This means that the reaction of sulphuric-acid leaching proceeds in diffusion–kinetic mode and that sodium fluoride is applicable as the leaching accelerator.