Experience of Hot Pack Rolling Application for Production of Specific Steels or Creep Resistant Alloys

Under the current conditions, the consumption of special purpose alloys or steels is growing. This is due to the development of the import substitution program. It should be noted, that such materials possess specific deformation behavior, which requires providing particular conditions of a hot rolling process. One of the characteristics of the deformation behavior is the narrow thermal plastic range. Therefore, it is necessary to conduct a hot rolling in several stages, which include interchange of heating and rolling processes. For the purpose to resolve the issue, the experience of the multilayer hot rolling of plates has been investigated where all advantages of this way of a hot rolling process were used. Based on the method of the multilayer hot rolling, the pack rolling has been developed which gives the possibility of production of hot-rolled plates from special purpose alloys or steels.

Elastic-Plastic Stresses in Shrink Fit with A Solid Shaft

Shrink fit joining a solid shaft and a cylinder requires an accurate estimate of the residual contact pressure to transmit high powers, as in the case of gas turbines. Such torques require deformations of materials beyond their elastic limits. This paper presents an analytical model that analyses the stresses in a shrink fit assembly consisting of a solid shaft and a cylindrical hub operating in the elastic-plastic range. Assuming the hub to have a nonlinear work-hardening material behavior, the distribution of stresses as functions of the interference, and the effect of geometry on contact pressure and on interference are exhibited. To validate the analytic method, Finite Element Method was used.

Elastic Rebound of a Blast Door Under Explosion Loadings

Rebound effects can be caused for a blast door under explosion loadings of conventional weapons. Such effects reaching a certain extent can lead to severe reversed stresses and even destroy the hinge and lock system before the door leaf. In this study, an analytical model for the elastic rebound of a blast door under explosion loadings was proposed and analyzed. Based on the calculations, the effects of aspect ratio and load duration on the rebound behavior were analyzed. Furthermore, for extension of the analysis from the elastic to plastic range, comparison of the solutions with the analytical ones was made. The results showed that the positive and negative dynamic shear force peaks of the blast door deceased gradually with the aspect ratio, whereas the rebound strength was inversely proportional to the load duration. For blast doors entering into the plastic stage, the rebound behavior was similar to the elastic stage, implying that the design of a blast door can be based on its characteristics in elastic stage.

Analysis of the Void Volume Fraction for S235JR Steel at Failure for Low Initial Stress Triaxiality

This paper deals with problems of failure mechanisms of S235JR structural steel. One of the fundamental parameters of the Gurson-Tvergaard-Needleman damage mechanics-based material model is considered in order to describe the behaviour of the material at the plastic range. The analysis was performed on the void volume fraction fF determined at failure of S235JR steel. The case of low initial stress triaxiality η = 1/3 was taken into consideration. Different from the most popular methods such as curve-fitting, the experimental method based on the digital image analysis of the fracture surface of S235JR steel is proposed in order to determine the critical parameter fF.

Effects of Reeling on Pipe Structural Performance—Part I: Experiments

The winding and unwinding of a pipeline in the reeling installation process involve repeated excursions into the plastic range of the material, which induce ovality, elongation, and changes to the mechanical properties. The reeling/unreeling process involves some back tension required to safeguard the pipe from local buckling. This study examines the effects of winding/unwinding a pipe on a reel at different values of tension on the induced ovality and elongation and the resulting degradation in collapse pressure. In Part I, a model testing facility is used to simulate the reeling/unreeling process in the presence of tension. The combination of reel and tube diameters used induces a bending strain of 1.89%. A set of experiments involving three reeling/unreeling cycles at different levels of tension is performed on tubes with diameter-to-thickness ratios (D/t) of 20 and 15.5 in which the progressive changes in cross-sectional geometry and elongation are recorded. Both ovalization and elongation are shown to increase significantly as the back tension increases. A second set of experiments on the same two tube D/ts is performed in which following a reeling/unreeling cycle at a chosen level of tension, the tubes are collapsed under external pressure. The collapse pressure is shown to decrease significantly with tension, which is primarily caused by the reeling/unreeling-induced ovality. Part II presents models for simulating reeling and the induced structural degradation. The experimental results in Part I are used to evaluate the performance of the models.