Authors: Lewin Rathmann, Frank Vollertsen

Abstract

In sheet metal forming contact between blank and die edge is reduced to local contact zones. For micro range, they can easily be found during a simulation, but an experimental evidence is difficult. Therefore, an optical projection of strip drawing with double deflection is presented and it is demonstrated that the contact zones can be identified using this method. These results are compared to those from simulation and it is shown that they reflect the simulative results. The results are presented on the basis of using a die with a die radius of r = 0.6 mm. The height of the gap between die edge and blank at the moment of their maximum distance is determined in the experiment to d = 18 ± 9 µm while it is d = 2 µm in the simulation. .

Key words: Micro forming; friction; simulation;

DOI: 10.24867/ATM-2018-2-001

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Author: Enikő Réka Fábián

Abstract

Nd: YAG laser welding of duplex stainless steels as 2205, LDX 2101, 2304, LDX 2404 grades were performed with and without addition materials. As additional material were used Metco 41C high nickel contain powder and 22 9 3 NL filler wire, conventional used for standard duplex stainless steels. The mechanical and corrosion properties of duplex stainless steels welds are dependent on microstructure and chemical composition. The additional materials favourable effects on mechanical properties were observed. The best pitting corrosion resistance were observed at specimens welded with wire addition. .

Key words: Laser beam, duplex stainless steel, additional material, microstructure;

DOI: 10.24867/ATM-2018-2-002

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Authors: Ismar Hajro, Petar Tasić

Abstract

The paper presents results of combined, conventional and non-conventional, approach for evaluation of mechanical and technological properties of structural steel's welded joints. The selected structural steels are in the range of most common used strength level(s), as well as corresponding various chemical composition concept(s) and processing routes. A short review regarding weldability is presented based on recommendation provided in EN 1011-2, manufacturers recommendation, and own results. However, even it is a well-known fact, mismatching of properties is presented rather to provide sense of its level for particular steel grades. Moreover, the level of under-matching of weakest weld zone (coarse grained heat affected zone), provided by mean of welding thermo-cycle simulation is presented. This is due to the fact that such estimation is not possible with everyday conventional (standardized) testing. The most important design and technological properties of welded joint(s) are considered; e.g. strength, ductility, hardness, microstructure and toughness.

Key words: Properties, mismatching, distribution, steel, welded joint;

DOI: 10.24867/ATM-2018-2-003

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Authors:Frank Schreiber, Benedikt Allebrodt, Tim Erpel

Abstract

The protection of machinery and structural components by thermal coatings is of huge economic importance. Each hour of downtime, caused by deficient coatings as a result of wear and corrosion, costs a fortune. Savings by reducing these downtime hours can be achieved by applying optimized functional coatings which show enhanced properties. The main welding processes for applying coatings are GMAW or OA, PTA or Laser, each with their pros and cons. The PTA process can be seen as the intermediate process bridging the low cost, high deposition rate and the expensive but high end Laser. Recently, the PTA and especially the laser process are gaining more attention and market shares. Nowadays the flux-cored wires can be upgraded more and more with for instance complex carbides and achieve coatings similar to the high performance coatings obtained by PTA and Laser welding but at much lower costs. The common problems accompanying the GMAW process: a large heat affected zone and dilution, can be circumvented by using the cold metal transfer (CMT), the AC-GMAW- and the GMAW hot wire process, allowing the flux-cored wires to fully deploy their large potential and compete with the welding techniques. The current paper will describe the modern GMAW hot wire process and then deal with innovative materials and process concepts for the high performance flux-cored wire to give a competitive alternative for the PTA process and expensive laser.

Key words: Thermal coatings; Flux-cored wire; GMAW-hot wire; Wear; Corrosion; Complex carbides.

DOI: 10.24867/ATM-2018-2-004

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Authors:Edvard Bjelajac, Tomaž Vuherer, Gorazd Lojen

Abstract

Weld cladding or weld overlay is a frequently used method for repair welding of damaged surfaces and for production of different surface coatings. The conventional coated electrodes have a circular cross-section. In order to increase the productivity and to decrease dilution and the depth of the heat affected zone (HAZ), the geometry of the electrode core was modified. Experimental weld cladding was carried out with rutile coated electrodes of rectangular cross-sections of 12.56×1 mm2, and for reference, also with a conventional ϕ 4 mm electrode Rutilen 2000 S. The coating of rectangular electrodes was identical and the core material almost identical to the materials of the standard electrode. The base material was the structural steel S355JR. The goal of investigation was to determine the welding parameters for the rectangular electrodes and to compare geometries and mechanical properties of the welds. Hardness and the dimensions of weld metal and HAZ were measured. Results with the 6.28×2 mm2 and 6.28×2 mm electrode were similar to the results with the standard electrode. However, with the 12.56×1 mm2 rectangular electrode, significantly lower currents were sufficient to obtain a good quality of the deposition layer. Due to possibility to weld with currents as low as 80-100 A, shallower and smaller HAZs and less dilution can be achieved with the rectangular 12.56×1 mm2 electrode than with standard cylindrical ϕ 4mm electrode.

Key words: Weld cladding; SMAW; rectangular coated electrode; weld geometry; dilution.

DOI: 10.24867/ATM-2018-2-005

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Authors:Darko Šunjića, Stipo Buljan

Abstract

Explosive forming appeared at the end of the 19th century as unconventional technology that provides new methods to get workpieces with bigger dimensions and complex geometries. As a source of energy this technology uses explosives. Explosive, as such, is relatively inexpensive and theoretically with it, it is possible to get any amount of energy that is needed. Explosive forming is used with other technologies such as deep drawing, expansion of pipes, welding etc. One of the main explosive characteristics is the velocity of detonation that can be determined, inter alia, with the Dautrich method. This paper clarifies the method and gives a case study with explosive Vitezit 20.

Key words: Explosion; metal forming; velocity of detonation, Dautrich method.

DOI: 10.24867/ATM-2018-2-006

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Authors:Alex Llerena, Viktor Gonda

Abstract

A planar finite element model is created for modeling the equal channel angular pressing (ECAP) processing of copper, by which the technological parameters can be determined for different initial parameters of the ECAP process. The structure of the model is described, as well as the extraction of the force and work data, furthermore results for the effect of the initial parameters, e.g. the friction and the frictional model on the extrusion force and work characteristics are shown.

Key words: equal channel angular pressing, extrusion, friction model, finite element simulation

DOI: 10.24867/ATM-2018-2-007

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Authors:Aleksandar Miletić, Peter Panjan, Miha Čekada, Pal Terek, Lazar Kovačević, Branko Škorić

Abstract

Efficiency and lifetime of manufacturing tools and mechanical components may be successfully improved by application of thin ceramic coatings. When it comes to tools for machining of hard materials such as machining of hardened steel, TiAlN is one of the most usually applied coatings. This material is of high hardness, high oxidation resistance and high temperature stability. In this research, surface morphology, mechanical and tribological properties of TiAlN coatings prepared in industrial deposition unit were studied. Three different coatings were prepared by selecting different rotational types in a magnetron sputtering deposition chamber. Surface morphology was characterized by stylus profilometry and atomic force microscopy, mechanical properties by nanoindentation technique and Rockwell indentation test, while pin-on-plate test was used to study tribological behavior. It was found that coatings prepared by higher number of rotations are smoother, harder, and more resistant to cracking and wear. These differences are attributed to differences in coating microstructure which refines with increased number of rotations.

Key words: Thin ceramic coating; TiAlN; magnetron sputtering; mechanical properties, friction, wear

DOI: 10.24867/ATM-2018-2-008

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