Search

This study presents results of the examinations aimed at determination of rheological properties of selected grades of medium and high-carbon steel grades (C45 and C72D). The examinations were carried out for the hot torsion test using STD 812 torsion plastometer. The results of experimental studies were approximated with the function used for determination of yield stress depending on strain, strain rate and temperature. The study allowed for development of mathematical models of rheological properties of steel grades studied in the analysed scope of parameters of strain and temperature. [ABSTRACT FROM AUTHOR]

The commercial technology of rolling 5,5 mm-diameter wire rod in Poland's most modern rolling line has been examined within the study. The material used for the investigation was the 20MnB4 steel intended for subsequent cold working. From the performed analysis of the investigation results it has been found that the technology of rolling wire rod of cold upsetting steel, which is used currently in the Rolling Mill under examination, allows the production of finished products that can be deformed with a relative reduction of about 33 %. At larger plastic deformations, cracks occur in the material, which disqualifies it from further cold working. [ABSTRACT FROM AUTHOR]

The paper presents results of theoretical and experimental studies on the effect of feedstock end overcooling before the first rolling stand on the plastic flow of metal and on the energy and force parameters during bar rolling process. From the obtained investigation results it has been found that the uniform heating of the feedstock in the stepped furnace does not insure the uniform plastic flow of metal over the rolled band length. Therefore, it is necessary to modify the method of feedstock heating in the stepper furnace in order to obtain a uniform temperature over the length of the feedstock before the first rolling stand. [ABSTRACT FROM AUTHOR]

In this work theoretical and experimental analysis of the backward extrusion with a rotary die of the AZ31 alloy has been performed. The modification of the classical extrusion was based on the use of a rotary die. The results of theoretical research have confirmed that the use of the modified backward extrusion causes the appearance of shear stress in deformed material, which could affects the activation of additional mechanisms of deformation. The numerical modelling of the rotating extrusion of AZ31 alloy has been conducted by using the computer program Forge®. The experimental tests were carried out in the conditions of the STD 810 torsion plastometer using newly designed tools. [ABSTRACT FROM AUTHOR]

The paper analyzes the high-temperature plasticity characteristics of 20MnB4 and 30MnB4 with micro-additives, intended for cold upsetting and high-carbon steels C45 and C70 in the "solid phase-liquid" during heating and cooling. The investigation was conducted to determine the plastic formability of the examined alloy under hot plastic working conditions. Experiments were carried out on the simulator Gleeble 3800 with the aim of determining the susceptibility of 20MnB4, 30MnB4, C45 and C70 steels to cracking at high temperature. The nil strength (NST), nil ductility (NDT) and ductility recovery temperatures (DRT), and the fracture toughness factor and the BRT (brittleness temperature range) have been determined. [ABSTRACT FROM AUTHOR]

The article presents results of the research concerning the physical modeling of plastic working of AZ31 magnesium alloy using two research methods. These studies were conducted using a metallurgical process simulator and torsional plastometer. The research was done for temperature range 200 ÷ 400 °C and strain rate from 0,1 to 20,0 s-1, depending on the testing method. The results allow to determine the coefficients in yield equation needed for the numerical research. Moreover the most advantageous temperature - velocity conditions to realize the process of bars rolling in three high skew rolling mill can be determined. [ABSTRACT FROM AUTHOR]