Martin Sahul

Resistance Spot Welding of dissimilar Steels

This paper presents an analysis of the properties of resistance spot welds between low carbon steel and austenitic CrNi stainless steel. The thickness of the welded dissimilar materials was 2 mm. A DeltaSpot welding gun with a process tape was used for welding the dissimilar steels. Resistance spot welds were produced with various welding parameters (welding currents ranging from 7 to 8 kA). Light microscopy, microhardness measurements across the welded joints, and EDX analysis were used to evaluate the quality of the resistance spot welds. The results confirm the applicability of DeltaSpot welding for this combination of materials.

Resistance Spot Welding of Low Carbon Steel to Austenitic CrNi Stainless Steel

The contribution deals with resistance spot welding of low carbon steel to austenitic CrNi stainless steel. The thickness of welded dissimilar steels was 2 mm. DeltaSpot welding gun with process tape was utilized for welding of the above-mentioned combination of steels. Resistance spot welds were produced under different welding currents. The welding currents used were 7 kA, 7.5 kA and 8 kA, respectively. Optical microscopy, microhardness measurement across the weld joint and EDX analysis across the weld joint interface were used to evaluate the quality of resistance spot welds of dissimilar steels.

Cryogenic Rotary Ultrasonic Machining of Titanium Alloys

Abstract Titanium alloys are utilized especially in applications that require a good combination of high strength, low mass and good corrosion resistance in aggressive environments. However, mechanical properties prejudge titanium alloys to hard machinability. Machining of titanium alloys is usually accompanied by cooling with liquids or gasses. One of the most effective cooling approaches is cooling by liquid nitrogen. Liquid nitrogen decreases temperature of tool, but also increases strength, hardness and brittleness of workpiece. One of the most suitable machining methods to machine hard and brittle materials is ultrasonic machining. In this article, rotary ultrasonic machining of titanium alloys under cryogenic conditions is analyzed.

Welding of Dissimilar Light Metals by Disk Laser

The paper deals with the welding of dissimilar light metals by TruDisk 4002 disk laser. AZ 31 magnesium alloy with the thickness of 1.0 mm and AW 5754 aluminium alloy with the thickness of 1.5 mm were selected as materials to be welded. The dissimilar welded metals were arranged in the overlapped configuration. Magnesium alloy was selected as an upper plate because of higher absorption of laser radiation. Argon with 30 l/min flow rate was used as shielding gas. Different focusing of laser beam was employed in order to decrease the power density and thus eliminate cracking of produced welds. Welded joints were produced through conduction mode of laser welding. Analysis of the welded joints was carried out by light microscopy, microhardness measurement and EDX analysis. Presence of a hard and brittle intermetallic compounds was observed at the weld metal/aluminium alloy interface.

IBA characterization of Ti-Si-C-N nanocomposite coatings

One of the new developing technologies for increasing hardness, wear resistance and lifetime of cutting tools are the Ti-Si-C-N nanocomposite coatings deposited by a LARC® method. To investigate the effect of the various coating deposition parameters on the coating properties, the Ti-Si-C-N layers were deposited on Ni2Cu backings. The nondestructive Ion Beam Analysis (IBA) was used for determination of elemental composition depth profiles of the prepared layers, so that samples can be further mechanically tested. By application of Rutherford Backscattering Spectrometry (RBS), Proton Induced X-ray Emission (PIXE), Elastic Recoil Detection Analysis (ERDA) and Nuclear Reaction Analysis (NRA) the concentration of Ti, Si, C, N and H was determined. The depth profiles of the individual elements in the surface area and in the layer interface with the backing material were also determined.One of the new developing technologies for increasing hardness, wear resistance and lifetime of cutting tools are the Ti-Si-C-N nanocomposite coatings deposited by a LARC® method. To investigate the effect of the various coating deposition parameters on the coating properties, the Ti-Si-C-N layers were deposited on Ni2Cu backings. The nondestructive Ion Beam Analysis (IBA) was used for determination of elemental composition depth profiles of the prepared layers, so that samples can be further mechanically tested. By application of Rutherford Backscattering Spectrometry (RBS), Proton Induced X-ray Emission (PIXE), Elastic Recoil Detection Analysis (ERDA) and Nuclear Reaction Analysis (NRA) the concentration of Ti, Si, C, N and H was determined. The depth profiles of the individual elements in the surface area and in the layer interface with the backing material were also determined.

Study of ZE10 Magnesium Alloy Welded Joints Produced with Disk Laser

The paper deals with the study of weldability of magnesium alloy with the addition of rare earth elements. ZE10 magnesium alloy with 0.06 wt. % of La and 0.08 wt. % of Ce was suggested as base material. The thickness of ZE10 magnesium alloy was 1.65 mm. TruDisk 4002 laser with the power of 2.0 kW was used for production of welded joints. Bead on plate welds were produced with various welding parameters. Laser power ranged from 0.5 kW to 1.8 kW, welding speed was in the range from 30 mm/s to 90 mm/s, focusing of the laser beam was within the range of -3 to 3 mm. Shielding gases argon, helium and nitrogen were used for protection of the weld pool against the ambient atmosphere. Light and electron microscopy, microhardness measurements across the welded joints interface and tensile test were utilized to analyze the welded joints.

Influence of Deposition Parameters on the Properties of Nanocomposite Coatings Prepared by Cathodic Arc Evaporation

The article deals with the influence of different deposition parameters on the selected properties of AlCrN/Si3N4 nanocomposite coatings. Bias voltage, cathodes currents and working gas pressure were changed during the deposition process. All coatings were deposited using Lateral Rotating Cathodes (LARC®) process that belongs to the group of cathodic arc evaporation PVD technologies. In comparison with the typical cathodic arc evaporation process which usually uses planar targets the LARC® process utilizes rotational cathodes that are positioned close to each other. Nanohardness, Youngs modulus, thickness and residual stresses were determinated in order to evaluate the influence of deposition parameters on these coatings properties

Nanohardness of DC Magnetron Sputtered W – C Coatings as a Function of Composition and Residual Stresses

The effects of residual stresses in thin W-C based coatings were investigated with the aim to find their influence on nanohardness and indentation modulus. Ten samples of W-C based coatings were deposited on microslide glass substrates using DC magnetron sputtering at the identical deposition parameters. Their thickness was in the range from 500 to 600 nm. The residual stresses in the coatings varied from 1.5 GPa up to 4.4 GPa. Increase of residual stress caused linear increase of HIT from 16 to 19.5 GPa. This increase was only the result of the compressive stresses. EIT of the studied coatings was not sensitive to residual stresses and corresponded to 185 GPa ± 15 GPa.

COMPARISON OF OXIDATION RESISTANCE OF TiAlN MONOLAYER COATING AND ITS nACo3 NANOSTRUCTURED VERSION

Abstract The contribution deals with comparison of oxidation resistance of classical TiAlN monolayer coating and its advanced high hard nanostructured and multilayered nACo3 version at elevated temperatures. Both coatings were deposited onto AISI M36 high speed steel using unique LAteral Rotating Cathodes process (LARC®). “In - situ” X-Ray diffraction analysis was employed for determination of the beginning of oxides creation and phase detection at different heating temperatures. Scanning electron microscopy fitted with EDX analysis was used for observation of fracture areas and measurements of coatings and oxide layers thicknesses as well. Determination of chemical composition of coatings surfaces and elemental linescans through the coatings and oxide layers were performed using EDX analysis. All measurements of these coatings were carried out not only before but also after the thermal annealing.