G. Stradomski

The Analysis of Al-Cu Bimetallic Bars Bond Layers Joined by the Explosive Method

The paper presents investigation results for obtaining a semi-finished product in the form of round Al-Cu bimetallic bars by the explosion method. The systems and technological parameters of explosion welding were selected in such a manner as to obtain finished bimetallic bars of an outer diameter of approx. 22 mm and a copper area fraction of the bimetal cross-section of approx. 15 and 30%. In this work was made an analysis of microstructure changes and the microhardness distribution on the cross-sections of the stock materials. There were also made tests of layers connections quality by determining the maximum shear stress on the joint boundary. The results show that the explosive cladding method guarantee a permanent connection of copper layers and aluminum core.

Eutectoid Decomposition of δ-Ferrite in Ferritic-Austenitic Duplex Cast Steel - Structural and Morphological Study

The influence of time and temperature of ageing on the σ-phase morphology in ferritic-austenitic cast steel have been investigated in this study. The morphology and quantity of the σ-phase were analyzed by using optical microscope, X-ray diffractometry, scanning electron microscope and image analysis, respectively. The annealing temperature has a significant influence on the morphology, volume fraction and the dynamics of σ-phase precipitation. Surface development of the σ-phase decreases from R=4.3, for the cast steel annealed at 700°C to R=2.4 for the cast steel annealed at 900°C, and the volume fraction Vvσ from 50.8% to 26.5%, respectively. The most rapid progress of δ → σ + γ’ transformation was observed at 800°C.

The Analysis of the Impact Relative Rolling Reduction at the Area Connector Bimetallic Plate after the Rolling Process

As part of this work the analysis of the impact relative rolling reduction at the connection area of bimetallic plate after the rolling process was carried out. The rolling process was conducted on samples that have been joined by explosive welding method [1-. The scheme of joining bimetallic plates with use of explosive welding method is shown in fig. 1 [. Geometric and structural design of explosively welded connections depends on the type of welded metal, welding process parameters and the thickness of welded components, the geometry of collision, the type of substrate and surface preparation. Regardless of the type of welded metal, there are three basic types of connections obtained with different parameters of welded plates: flat connections without an intermediate layer of the symmetric deformation of grains, wavy connections and the last one with continuous intermediate layer. This paper presents the analysis of sheet metal connection area after direct double-layer combining by explosive welding method and the next stage of their production - the rolling process. Bimetal plates Al99.8-M1E were rolled with relative rolling reduction ε = 10%, 15% and 20%. The analysis of structural changes was made for both kinds of the samples: after the direct connection and after the annealing operations. In addition to analyzing the results of optical microscopy to present a complete picture of changes in the joints the Vickers micro hardness testing were carried out. Fig. 1. Scheme mergers bimetal plate explosive welding method [5]

The Analysis of Hip Joint Prosthesis Head Microstructure Changes during Variable Stress State as a Result of Human Motor Activity

The paper present the analysis of metal prosthesis head stress state of hip joint endoprosthesis which is a result of variable loads during human motor activity and its influence on the erosion of materials. The analysis of stress state was made with use of FEM – ADINA numerical tool. The analysis of surface erosion process was made with use of the scanning electron microscope. To the researches was taken for heads from CoCrMo bearing shell and polyethylene UHMWPE.

Analysis of Asymmetrical Rolling Process of Multilayer Plates

. Literature provides three basic methods of explosive cladding, developed by Darenport and Person. Welding trials were performed in two- and three-layer arrangements, where in the second case, copper plates were welded with plates made from aluminium alloys with an interlayer of pure aluminium. Explosive welding technology does not always allow for joining of sheets of specific thicknesses. In order to obtain such thickness, they need to be rolled. The paper presents results of numerical study of asymmetrical rolling process of multilayer plates M1E-Al99.8-AlMg5. Numerical modeling of rolling of multilayer plates was realized by means of Forge 2D program that is based on finite element method. Obtained research results enabled to elucidate the process of rolling of multilayer plates.

The Microstructure Change during Modeling of Conventional and Thermo-Mechanical Rolling of S355 Steel Bars

Substantial differences – mainly in plasticity – were found based on statistical analysis of hot rolled bars mechanical properties. Investigations presented in the paper were related to the possibility of modification of continuous bar mills used now in order to improve and stabilise plastic properties determined by the energy of breaking. The paper presents results of laboratory investigations representing processes of conventional and normalising rolling of bars from S355 steel. The experimental analysis of both rolling processes comprised assessment of actual changes occurring in the microstructure of bars, deformed acc. to suggested parameters corresponding to conventional and normalising rolling. The investigations included also the assessment of accelerated cooling after rolling influence on the microstructure of finished products.