Unreacted MgB 2 wires fabricated from SiC-doped precursor material by Hyper Tech Research, Inc. have been used to make small-diameter (14 mm) superconducting coils. All coils made of 500 mm length wires were subjected to hot isostatic pressure (HIP) treatment. The critical current density (J c ) parameters of coils were compared to straight samples characteristics. Both types of samples have been measured in perpendicular magnetic field configuration for J c and pinning force density (F p ) evaluation. No significant J c difference between the long wires on coils and straight wires was found. These results suggest that the critical current (I c ) for coils can be determined for straight samples (25 mm). SEM analysis indicated that a small diameter of the coil does not influence the structure of in situ MgB 2 wire.

This article presents the analysis of the deformability, structure and properties of the AZ61 cast magnesium alloy on the example of a new forging process of aircraft mount forgings. It was assumed that their production process would be based on drop forging on a die hammer. Two geometries of preforms, differing in forging degree, were used as the billet for the forging process. It was assumed that using a cast, unformed preform positively affects the deformability of hard-deformable magnesium alloys and flow kinematics during their forging and reduces the number of operations necessary to obtain the correct product. Numerical analysis of the proposed new technology was carried out using DEFORM 3D v.11, a commercial program dedicated to analyzing metal forming processes. The simulations were performed in the conditions of spatial strain, considering the full thermomechanical analysis. The obtained results of numerical tests confirmed the possibility of forming the forgings of aviation mounts from the AZ61 cast magnesium alloy with the proposed technology. They also allowed us to obtain information about the kinematics of the material flow during forming and process parameters, such as strain intensity distribution, temperatures, Cockcroft–Latham criterion and forming energy. The proposed forging process on a die hammer was verified in industrial conditions. The manufactured forgings of aircraft mounts made of AZ61 magnesium alloy were subjected to qualitative tests in terms of their structure, conductivity and mechanical properties.

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Ring rolling is a hot forming process for producing rings that have large diameters when compared to their cross sections. This process is very dynamic and involves considerable variations in ring shape and size. One of the failure modes in ring rolling processes is slip that occurs when a thickness reduction, exceeds the limit value. The thickness reduction depends on the tool speed and dimensions as well as ring size, and varies over time. This paper reports results of a study investigating the thickness reduction with respect to slip occurrence. In terms of wall thickness reduction, the process can be divided into three distinct stages (excluding the sizing stage): (i) initial stage corresponding to the first revolution of the roll, (ii) main stage, when the proper ring rolling takes place, (iii) final stage, when the main roll does not move in an axial direction but the ring is being formed during one revolution of the tool. It has been found that the most slip-prone moment is the end of the second and the beginning of the third stage of the ring rolling process, when the wall thickness reduction is the highest. Based on a comparison of the calculated thickness reduction and its limit values, it could be predicted whether slip would occur, and if so – in what stage of the rolling process. Numerical results and experimental findings are in good agreement.

The originality of this paper lies in the presentation of a new, innovative method for manufacturing medical screws with a cylindrical head of 316 LVM. This method is unique on a global scale, and its assumptions have been granted patent protection. The paper presents selected results of theoretical and experimental research on the developed process of forming of medical screws based on new technology. In the first part of the study a review of the types of screws used in the medical industry is made and the previous methods of their manufacture are described. The second part of the paper presents the assumptions and analysis of the elaborated process of metal forming of medical screws with a cylindrical head and ring thread made of 316 LVM austenitic steel. The theoretical analysis of the new process of forming a screw selected for testing was performed on the basis of numerical simulations. The experimental verification of the proposed theoretical solutions was carried out on the basis of laboratory tests, industrial research and qualitative research. The positive results obtained from computer simulations and experiments confirmed the effectiveness of the developed technology and the validity of its use in future in industrial practice.