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J. Michalczyk and T. Bajor

Study on the Influence of Temperature, Velocity and Shape of Tools on the Combined Process of Extrusion and Broaching of the Deep Sleeve with the Bottom Made of the AZ31 Alloy

The article presents the results of a theoretical analysis of the manufacturing process of the deep sleeve with the bottom by means of a method of combining the indirect extrusion of a thick bush and broaching the blank through the conical die in one cycle of the stamp. The main advantage of application of the developed method for production of the sleeve is to reduce demand for energy and force compared to traditional methods of producing the deep sleeve. Moreover, the nature of the single operation of the extrusion process and extension of the sleeve eliminates the necessity of additional treatments: soft annealing, reheating the charge and reducing wall thickness of the sleeve by a second tool, which significantly reduce energy, labour and time consumption of production. Numerical calculations were performed in the Forge ® 2D using plane state of strain and the obtained results allowed to determine the forces necessary for the process and the strain limit, as well as die geometry and impact velocity on the process tool.

Open access

T. Bajor, H. Dyja and K. Laber

This study presents the results of physical modelling of the processes of metal forming of bars made of magnesium alloy (AZ61) obtained using two research methodologies. The study employed the Gleeble 3800 testing system for simulation of metallurgical processes and a torsion plastometer. Depending on the research methodology used, the examinations were carried out in the temperature range of 200 ÷ 400°C and strain rate of (0.1 - 10 s-1). The results obtained in the study were used to determine the value of yield stress for AZ61 alloy for different strain procedures and different temperatures and strain ratios.

Open access

S. Mróz, P. Szota, T. Bajor and A. Stefanik

Abstract

The paper has presented the results of theoretical studies and experimental tests of the plastic deformation of Mg/Al bimetallic specimens. Theoretical studies were carried out using the Forge2011® computer program. Physical modeling, on the other hand, was performed using the Gleeble3800 simulator. Bimetallic bars of an outer diameter of 22.5 mm and a cladding layer thickness of 1.7 mm were obtained by the explosive welding method. Samples for formability tests, characterized by a diameter-to-length ratio of 1, were taken from the bars. The theoretical studies and experimental tests were carried out for the temperature range from 300 to 400°C and for different strain rates. Based on the obtained investigation results it has been found that the main parameters influencing the formability of Mg/Al bimetallic bars are strain rate than the process temperature.

Open access

A. Stefanik, P. Szota, S. Mróz, T. Bajor and H. Dyja

Currently magnesium alloy bars are manufactured mainly in the extrusion process. This method has some drawbacks, which include: low process capacity, considerable energy demand, small length of finished products. Therefore it is purposeful to develop efficient methods for manufacturing of Mg alloy products in the form of bars, such methods include groove rolling and three-high skew rolling processes. Modified stretching passes provide change in material plastic flow, which contributes to the occurrence of the better distribution of stress and strain state than in the case of rolling in classical stretching passes. One of the modern method of Mg alloy bars production is rolling in a three-high skew rolling mill, which allows to set in a single pass a larger deformation compared to the rolling in the stretching passes.

The paper presents the results of experimental studies of the AZ31 round bars production in the modified stretching passes and in the three-high skew rolling mill. The study of microstructural changes, hardness and the static tensile tests were made for as-cast and ready-rolled bars in both analyzed technologies.

Open access

H. Dyja, E. Tussupkaliyeva, T. Bajor and K. Laber

Abstract

The continuing high level of demand for lightweight structural materials is the reason for the ever-growing interest in aluminum alloys. The main areas of application for aluminum alloys products are the aerospace and automotive industries. Production of profiles and structural elements from lightweight alloys gives possibility to reduce the curb weight of construction, which directly translates into among other reduction of fuel consumption and lower amount of generated exhaust gas.

Determination of heat treatment and plastic working parameters to obtain the required mechanical properties of the manufactured products is a complex process that requires among others knowledge of the material behavior during the deformation process. To carry out the study the torsion plastometer STD 812 was used. On the basis of obtained results of the research the value of the yield stress, formability limit and the thermal effect of the deformed 7xxx series aluminum alloy were specified for different schemes and conditions of deformation.