Computer simulation of microstructures evolution for three-high cross-rolling of hollow steels
Based on the rigid-plastic finite element method (FEM), an investigation on three-high cross-rolling of hollow steels was carried out in this study. The numerical model coupled thermal, mechanical and microstructural phenomena, in which some empirical recrystallization mode were obtained using the Gleeble-3500 thermomechanical simulator. The distributions of different field-variables, including temperature, strain and grain size, were obtained by FEM simulation. After different mandrel diameters were calculated, the investigation obtained the effect of microstructures evolution and compared the grain size between no mandrel and different mandrel diameters.
Critical strain for dynamic recrystallization in variable strain rate hot deformation
In rolling, the strain rate in a rolling pass is not constant but depends on pass reduction r p , decreasing or increasing along the arc of contact. In the present work, high temperature compression tests were performed with the rate varying according to strain rate profiles pertaining to various flat rolling pass reductions. Due to the high rate sensitivity of the stress at elevated temperatures, the stress follows such variations in strain rate. This can lead to peaks in the flow curves without regard to dynamic recrystallization (DRX). Nevertheless, critical strains for the onset of DRX can still be defined if the stresses and strains in variable strain rate deformation are normalized by the peak stresses and strains that would be observed if the deformation were being performed at a series of constant strain rates equal to that of successive points along the roll bite. Using plain carbon and Nb-bearing steels, it is demonstrated that the DRX critical strains are lower when r p 30% than in constant e deformation at the same initial strain rate. The present method permits the more accurate extrapolation of laboratory test results to industrial conditions and enables rolling loads to be analyzed with greater precision.
Preparing for group analytic psychotherapy: meeting the new patient
Preparing for group analytic psychotherapy—the patient and yourself as a therapist—is apparently done in many ways and still invested with much controversy and ambivalence. Some say, they do no selection or assessment at all. The patients or clients are taken from the waiting list in alphabetic order. Other therapists—mainly those working in National Health Services—use several assessment interviews before including patients into short- or long-term groups. Either way, this article revives some research results about assessment and hopes to inspire therapists in their first contact with the patient by presenting some examples from a clinical outpatient practice in a mental health service.