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Gliwice, Poland

Zupanc U.,Welding Institute | Grum J.,University of Ljubljana
Journal of Materials Processing Technology | Year: 2010

Pitting corrosion has a major influence on aging of structural elements made of high-strength aluminium alloys as corrosion pits lead to earlier fatigue crack initiation under tensile dynamic loading. A cause of fatigue crack initiation in a corrosive medium is a stress concentration at a corroded area. In order to improve material resistance to corrosion fatigue it is necessary to reduce pit-tip stresses. To eliminate or reduce pit stresses, cold surface hardening by shot peening was proposed. The objective of the present study was to investigate the effect of surface hardening by shot peening on electrochemical stability and corrosion fatigue properties of high-strength aluminium alloy 7075-T651 in the corrosive environment of a chloride solution. The results obtained show a favourable influence of shot-peening treatment on corrosion fatigue properties. Induced compressive residual stresses in the surface layer retard the initiation of fatigue cracks, and so the fatigue life improvement of structural elements made of high-strength aluminium alloys was observed. © 2010 Elsevier B.V. All rights reserved.

Gola B.,Welding Institute
Welding International | Year: 2014

The purpose of liquid-penetrant inspection of metallic structures of historic value is the assessment of their technical state and suitability for further operational use. In this paper, the flaws of metal structures detected by means of penetrant inspection, conditions under which inspection can be made, requirements for inspection personnel, liquid-penetrant sets, measuring and auxiliary equipment and the inspection course are discussed. As an example, the results of inspection of a section of the riveted structure of an antique workshop roof are presented. © 2014 Taylor & Francis.

Niagaj J.,Welding Institute
Welding International | Year: 2014

We discuss the methods of stainless steels welding and the trends of their development from the viewpoint of increase in productivity and effectiveness of welding. It has been found that apart from mechanization and robotization, the development of stainless steel welding processes takes place by working out new variants of particular welding methods as well as by implementation of modern welding equipment and application of special welding consumables. © 2014 © 2013 Taylor & Francis.

Dworak J.,Welding Institute
Welding International | Year: 2014

We present the general characteristics of laser welding technology with the use of the radiation beam emitted in the pulse mode. The relationships between energy parameters of the pulse radiation beam are. We show that the pulse shape (i.e. defined course of power changes during pulse endurance) is one of the laser beam parameters affecting the welding process course, especially that in which thin precise elements are involved. By means of demonstration melting and welded joints of selected materials, the possibility of changing the weld shape and the manner of the weld metal crystallization through the application of different shape laser beam pulses is illustrated. © 2013 © 2013 Taylor & Francis.

The application of low-energy methods of metal inert gas welding (ColdArc and CMT) for the manufacture of joints in hard-weldable aluminium alloys is presented. The purpose of the technological research was to show the usefulness of the CMT and ColdArc methods for production of butt and T-joints in 2.0 mm thick aluminium alloy plates. Basic difficulties related to welding of 6xxx and 2xxx series aluminium alloys and the specificity of welding by low-energy methods are discussed. Selected results of metallographic macro- and microscopic examination as well as those of tensile and bend tests are given; detailed analysis of the results is also carried out. The article shows also that ColdArc and CMT methods provide high quality and aesthetic welded joints in aluminium alloys that are considered to be non-weldable or of limited weldability. © 2014 © 2012 Taylor & Francis.

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