Estimation of minimal slab reduction to eliminate of axial porosity

In the production of the continuous cast slabs using continuous-casting machine, the formation of axial porosity is observed. Method for determination of the minimal reduction of the workpiece during hot rolling in order to eliminate the axial defect is presented. The theoretical dependences for transformation of the axial porosity on drawing and the reduction rate of continuously cast slab during hot rolling are obtained based on assumptions.

Improvement of Plate’s Shape for Ingots Upsetting

A stress-strain state and a resize of an axial defect during upsetting have been investigated in the article. Theoretical research based on a FEM has been conducted. The upsetting of cylindrical steel workpieces which had the axial defect equal to 10 % of the workpiece diameter has been simulated. Upsetting has been carried out by flat, concave-conical and convex plates (solid or with hole). The result of the studies showed that the main influence on the workpiece shape had a ratio of dimensions. The maximal closure of the axial defect provides upsetting by concave-conical solid plates. Upsetting by flat plates does not provide the closure of axial defects. Convex plates provide the uniform stress-strain state along the workpiece cross section. The hole in the plates increases the non-uniformity of strain distribution and also does not provide the axial defects closure.

The Limit Pressure for a Cracked Branch Junction and Comparison With a Cracked Plain Cylinder

The limit load of structures that contain defects may be determined using standard limit load solutions for simple components or by employing Finite Element (FE) procedures for more complex structures. This work considers the case of a pressurised piping branch junction (D/T = 20, d/D = 0.5, t/T = 1) which contains two axial through-wall cracks, symmetrically extending from each crotch corner at the crown of the junction. The structure is idealised as a plain cylinder containing a single axial defect with three proposed definitions of an equivalent crack length. Such a cracked cylinder can be analysed using a standard limit load solution or by FE analysis. The three crack length definitions used are the distance between the two outer crack tips, the sum of the two crack lengths and the length of one of the cracks. Estimates of branch junction limit pressures have been obtained by FE analysis using ABAQUS for a range of crack lengths. These are compared with the theoretical solutions for an equivalent plain cylinder of the run pipe dimensions containing a single crack whose length has been defined in each of the above ways.

Effect of Composite Damage on the Fatigue Behavior of the Metal-Lined Hoop-Wrapped Cylinders

Effects of an axial defect in the composite of hoop-wrapped steel and aluminum cylinders on the hoop stress as well as on the bulging of the liners were investigated through the numerical and experimental stress analysis. Comparison with the experimental results (reported in reference [5]) suggests that relative fatigue performance of the cylinders, containing damages to the composite wrapping, can be assessed without conducting prototype tests.

Identification of Impurities and Defects in Semiconductors by Optical Spectroscopy

A review is given of the information that can be obtained on defect centers in semiconductors by optical spectroscopy. Particular emphasis is given to donor and acceptor identification, and symmetry determination of transition metal and axial defect-complex centers. The information that can be obtained from isotope doping effects is discussed.