Search results

Filters

  • Journals
  • Date

Search results

Number of results: 5
items per page: 25 50 75
Sort by:

Abstract

Paper present a thermal analysis of laser heating and remelting of EN AC-48000 (EN AC-AlSi12CuNiMg) cast alloy used mainly for casting pistons of internal combustion engines. Laser optics were arranged such that the impingement spot size on the material was a circular with beam radius rb changes from 7 to 1500 m. The laser surface remelting was performed under argon flow. The resulting temperature distribution, cooling rate distribution, temperature gradients and the depth of remelting are related to the laser power density and scanning velocity. The formation of microstructure during solidification after laser surface remelting of tested alloy was explained. Laser treatment of alloy tests were perform by changing the three parameters: the power of the laser beam, radius and crystallization rate. The laser surface remelting needs the selection such selection of the parameters, which leads to a significant disintegration of the structure. This method is able to increase surface hardness, for example in layered castings used for pistons in automotive engines.
Go to article

Abstract

In the present study, Ti6Al4V titanium alloy plates were joined using robotic laser welding method. Pre- and post-weld heat treatments were applied to laser welded joints. After welding stress relieving, solution heat treatment and ageing were also applied to preheated laser welded samples. Effects of heat treatment conditions on microstructural characteristics and mechanical properties of robotic laser welded joints were studied. Aged samples were found to be made of coarsened grains compared to microstructures of non-aged samples. There were increases in ductility and impact toughness of samples applied to ageing increased, while hardness and tensile strength of non-aged samples were higher. The highest value for tensile strength and for impact toughness in welded samples have been identified as 840 MPa and 27 J, respectively. Fractures in tensile test samples and base metal impact test samples took place in the form of ductile fracture, while laser welded impact test samples had fractures in the mode of intergranular fractures with either a quasi-cleavage type or tear ridges. EDS analysis carried out for all heat treatment conditions and welding parameters demonstrated that major element losses were not observed in base metal, HAZ and weld metal.
Go to article

Abstract

The paper described properties of electro-spark deposited coatings under influence of the laser treatment process. The properties were assessed by analyzing the coating microstructure, X-ray radiation, microhardness, bonding strength, corrosion resistance, porosity and wear tests. The tests were conducted for Mo and Cu coatings (the anode) which were electro-spark deposited over the C45 steel substrate (the cathode) and melted with a laser beam. The coatings were deposited by means of an ELFA-541. The laser processing was performed with an Nd:YAG laser. The coatings after laser processing are still distinguished by very good performance properties, which make them suitable for use in sliding friction pairs.
Go to article

Abstract

In the study, particle size distribution of the MIEX® resin was presented. Such analyses enable to determinate whether presence of fine resin fraction may be the reason for unfavorable membrane blocking during water purification by the hybrid MIEX®DOC – microfiltration/ultrafiltration systems. Granulometric analysis of resin grains using the laser diffraction particle size analyzer (laser granulometer) was carried out as well as the microscopic analysis with scanning electron microscope. The following samples were analyzed: samples of fresh resin (a fresh resin – not used in water treatment processes) and samples of repeatedly used/regenerated resin that were collected to analysis during mixing and after sedimentation process. Particle size distribution was slightly different for fresh resin and for repeatedly used/regenerated resin. The grains sizes of fresh resin reached approximately 60 μm (d10), 120 μm (d50) and 220 μm (d90). Whereas the sizes of repeatedly used/regenerated resin were about 15 μm (d10), 40 μm (d50) and 115-130 μm (d90). The smallest resin grains sizes were in the range of 0.3-0.45 μm. This ensures that the ultrafiltration membranes retain all resin grains, even the smallest ones. Whereas the microfiltration membranes must be appropriately selected to guarantee full separation of the resin grains and at the same time to exclude a membrane pores blocking.
Go to article

This page uses 'cookies'. Learn more