Model for Predicting the Lankford Coefficient of Industrial Sheet of Automotive Steels

A model is proposed for predicting the Lankford coefficient of steel sheet produced for the auto industry at PAO Severstal. The set of empirical model parameters is determined using an experimental database on the mean Lankford coefficient (for 138 strips of 13 steels differing greatly in composition) and additional databases on calculated steel microstructure parameters after hot rolling, and after heat treatment of cold-rolled strips. The mean error in calculations of the Lankford coefficient using the model is 7.1%. It is found that the Lankford coefficient is determined not only by the carbon content in the solid solution before cold rolling but also by the amount of carbon deposited at the ferrite grain boundaries in the form of tertiary cementite. The additional free carbon appearing in the solution when the tertiary cementite particles dissolve on heating of the cold-rolled sheet significantly affects the recrystallization and the texture formation.     

Surface-crack formation in the manufacture of microalloyed steel pipe

Deform-3D software is used to model surface-crack formation in the rolling of thick sheet on a 5000 mill. The calculations show that the temperature field and stress state are relatively uniform over the width of the sheet, except at the edges. The minimum temperature of the surface layers of metal hardly depends on the sheet thickness and the relative reduction per pass. The Cockroft–Latham criterion is used to analyze the probability of steel failure in rolling. Analysis shows that metal failure may occur at points where ferrite appears, especially at the instant that the metal leaves the deformation region. Considerable tensile stress acts at those points.     

Role of Martensite-Austenite Component of Bainitic Structure in Formation of Properties of Pipe Steel. 1. Effect of Parameters of TMT

Metal Science and Heat Treatment - The effect of parameters of hot rolling and controlled cooling on formation of the martensite-austenite component of bainitic and ferritic-bainitic structures in...     

Anxiety and hemodynamics: correlations in hypertensive patients

AIM: Syndrome analysis of functional relationships between personality disorders, autonomic regulation and psychic performance in relation to hemodynamic condition of hypertensive patients. MATERIALS AND METHODS: MMP1, Tailor's anxiety scale, Burdon and Schulte tables, variation pulsometry, tetrapolar chest rheography were used in examination of 86 patients with stage I and II hypertension. RESULTS: In early hypertension, weak anxiety and subclinical emotional disturbances, dominant was a parasympathetic trend of the vegetative tone without central control of the cardiac rhythm in hyperkinetic circulation. Changes in cortical neurodynamics manifested with minor attenuation of the ability to focus attention. Progression of angiospasticity and anxiety gave rise to psychic maladjustment in the form of anxiety-depression disorders with autonomic dysfunction in hypokinetic circulation, overcentralization of cardiac rhythm control. This was associated with a decline in mental performance. CONCLUSION: Systemic investigations of the emotional sphere, central hemodynamics and autonomic regulation of cardiac rhythm enable assessment of multilevel structure and severity of psychocardiac syndrome in hypertensive patients which is important both for therapeutic and expert practice.     

Mechanical properties of alloys with reversible martensitic transformation

Characteristics of the formation of properties of alloys with reversible martensitic transformation are examined from positions of the theory of structure formation in open, highly nonequilibrium, thermodynamic systems. It is shown that strain hardening of a metal is linearly connected with change in entropy and is a measure of the nonequilibrium state of the system and that it can be used for calculating the entropy change. Based on analysis of the energy state of the material, the article establishes that it is possible to determine stress levels corresponding to instant of loss of the form memory effect with plastic deformation and to failure under a simple type of stress. Calculated values of these characteristics of alloys are in good agreement with experimental data of the authors and other published data. The thermodynamics of reversible martensitic transformation are examined.Translated from Problemy Prochnosti, No. 3, pp. 34–42, March, 1992.     

Stability of Untransformed Austenite in M/A Phase of Bainitic Structure of Low-Carbon Steel

Metal Science and Heat Treatment - A concept is developed for assessing the stability of untransformed austenite entering the martensite-austenite component of a bainitic structure, which is...     

Tension-compression method in the simulation of multistage plastic deformation

The utility of extension-compression cycles in the simulation of multistage plastic deformation on a Gleeble thermomechanical complex is confirmed. In the experiments, the microstructure and properties of the metal are compared after rolling on a 210 laboratory mill and after treatment on the MaxStrain, Torsion, HydraWedge, and Pocket Jaw modules of the Gleeble-3800 simulator. Those modules differ in terms of the stress-strain state reproducible within the deformation zone. The results show that the tension-compression method developed for the Pocket Jaw module may be successfully used in simulating complex processes of multistage plastic deformation: rolling, forging, stamping, etc.