Direct X-ray observation of lattice parameter changes due to magnetostriction in nickel single crystal

Journal of Materials Science -     

SOME IMPLICATIONS OF THE USE OF THE PD6493 LEVEL 3 FAILURE ASSESSMENT PROCEDURE

Abstract— Under a natural mapping between the standard R-curve analysis diagram and the failure assessment diagrams of R6 and PD6493 Level 3 the R-curve becomes the RCI (R-curve image). It follows that whenever the assessment point moves along the failure assessment line during ductile crack growth, the implication is that the failure assessment line is the RCI. This result is used to test the conservatism of a specific PD6493 Level 3 analysis by two methods. The first calculates the variation during crack growth of the applied elastic-plastic crack tip opening displacement (CTOD) parameter (or‘driving force') which is implied by the PD6493 analysis and then compares this variation with an independent estimate of it. The second uses an assumed driving force to deduce the CTOD resistance curve implied by the failure assessment line. It is shown by both methods and also by a direct R-curve analysis that this particular PD6493 analysis is conservative relative to an R-curve analysis which uses a crack driving force estimated by the EPRI (Electric Power Research Institute) procedures. However there is inconsistency between standard R-curve analysis and PD6493 Level 3 analysis in that the latter implies a material resistance which, for a given material, depends on the geometry of the structure. A similar inconsistency arises in any failure assessment procedures like the Options 1 and 2 with Category 3 of R6, which require the assessment point to move on a geometry independent failure assessment line during crack growth; indeed, even when the failure assessment line is geometry dependent there is full agreement with R-curve analysis only if the correct RCI is used as the failure assessment line. In a brief discussion it is noted that the new failure assessment diagram studies involving multi-parameter fracture mechanics may help to ameliorate these problems.     

Use of a ductile fracture model for pipes with axial defects for analysis of results of full-scale experiments

We consider the use of a ductile fracture model for pipes with axial defects, loaded by internal pressure, for calculation of the limiting burst pressure P_LL. We describe procedures for hydraulic and pneumatic testing of full-size pipes performed at VNIIST (All-Union Scientific Research Institute for the Construction of Trunk Pipelines, Moscow), and also the scheme for application of a surface notch. We have done a comparative analysis of the value of P_LL calculated from the relationships determined on the basis of a ductile fracture model for cylindrical bodies with cracks and the value obtained using familiar empirical formulas. Based on the calculations, we plot graphs for the distribution of the deviation of the calculated burst pressure from the true burst pressure as a function of the relative crack length ². We demonstrate the considerable effectiveness of the ductile fracture model for pipes with defects, which allows us to take into account the real shape of the defect and additional mechanical actions (longitudinal forces, bending moments).Translated from Problemy Prochnosti, No. 6, pp. 5–15, November–December, 1996.     

Effects of tensile stresses on corrosion parameters for model crack grooves

Summary Measurements have been made on the electrochemical parameters in a model corrosion gap as affected by tensile stresses varying from zero up to the yield point of the material. It is shown on various constructional materials (D16T aluminum alloy, steel 45, Kh18N12T steel, and PT-3V titanium alloy) that the passivation time for a freshly renewed surface is reduced by a factor 1.5–3.5 as increases, while the galvanic current increases by a factor 1.2–3.0 and the electrode potentials shift by 30–100 mV in accordance with the pH. Numerical values are given for the parameters as functions of and pH.Translated from Fiziko-Khimicheskaya Mekhanika Materialov, Vol. 26, No. 4, pp. 22–25, July–August, 1990.     

New halide glasses of the CdX2-PbX2-KI (X=Cl,Br) systems

The glass forming regions and some properties of the CdBr₂-PbBr₂-KI (10 to 50 mol % CdBr₂, 10 to 70 mol % PbBr₂, 20 to 40 mol % KI), CdCl₂-PbBr₂-KI (10 to 50 mol % CdCl₂, 10 to 80 mol % PbBr₂, 10 to 70 mol % KI) and CdCl₂-PbCl₂-KI (20 to 50 mol % CdCl₂, 10 to 70 mol % PbCl₂, 5 to 60 mol % KI) ternary systems were studied. Glasses exhibit remarkably high transmittance (up to 80%) in the visible and IR region (down to 250 cm^–1 for CdBr₂-PbBr₂-KI, 300 cm^–1 for CdCl₂-PbBr₂-KI and 400 cm^–1 for CdCl₂-PbCl₂-KI for 1 mm thick plates). The values of glass transition temperature lie between 343 to 353 K and crystallization temperature between 343 to 403 K.     

Peculiarities of the relaxation properties of the FeCrNi alloy spin system at low temperatures

The types of spin system exhibited by certain FeCrNi alloys were studied using the gamma resonance spectra technique. It was evident that the spin systems were significant in determining the magnetic and physical properties of these alloys at low temperatures. It was found that antiferromagnetic and ferromagnetic ordering of the alloys took place in small regions and the character of each region depended upon its Ni content.