Tungsten inert gas (TIG) welding of aluminum alloy EN AW-AlZn5.5MgCu

The paper presents the results of tungsten inert gas (TIG) welding of aluminium alloy 7075-T6 in the butt joint, with single-V edge preparation. The sample dimensions were 100 × 75 × 20 mm3. The TIG welding was done with 2 mm diameter filler wire made of 5183 (AlMg4,5Mn) at four preheating temperatures. During the welding a temperature was measured at six locations with thermocouples. For successfully welded samples tensile test were done and microstructure of base metal, heat affected zone and weld was analysed. The welds brake at heat affected zone between base metal and the weld. The optimal preheating temperature was at 200 °C

How to Extend the Life of Die-Casting Tools

The paper explores some possibilities of extending the life of die-casting tools for non-ferrous metals, particu-larly aluminium, magnesium, and their alloys. In the first part of the paper is shown theoretical background of the problem. The major part treats the tools: tool life, tool manufacture, tool certificate, tool operation and repair of tools by welding. Welding is the only technology fit for repair of tools and thus to extend their service life. In the paper is shown some welding processes, which are suitable for repair welding of tools

Laser grooving of surface cracks on hot work tool steel

The paper presents the analysis of laser grooving of 1.2343 tool steel hardened to 46 HRC. The effect of laser power and grooving speed on groove shape (i.e. depth and width), the material removal rate and the purity of produced groove as a measure of groove quality was investigated and analyzed using response surface methodology. Optimal parameters of laser grooving were found, which enables pure grooves suitable for laser welding

Refurbishment of damaged tools using the combination of GTAW and laser beam welding

This paper presents the use of two welding processes for the refurbishment of damaged industrial tools. In the first part the problem is presented followed by the comparison of GTAW and laser welding in terms of repair welding of damaged tools. The macrosections of the welds show the difference between both welding processes in repairing of damaged tools. At the conclusion the main findings are presented. In many cases it is useful to use both welding processes in order to achieve better weld quality and to make welding more economical. The order of the technology used depends on the tool material, the use of the tool and the tool damage

Utjecaj parametara zavarivanja na skrućivanje zavara kod feritnog nehrđajućeg čelika

The paper presents the analysis of solidification mode at gas tungsten arc welding (GTAW) of AISI 430 ferritic stainless steel. Two solidification modes (epitaxial and equiaxial) were discovered, which have a major influence on a weld tensile strength. The optimal welding parameters for ferritic stainless steels were found in a narrow range. They should be selected according to mechanical strength of the welded joints and not only according to their visual appearance.U radu je prikazanaanaliza skrućivanja zavara kod TIG zavarivanja AISI 430 feritnog nehrđajućeg čelika. Dva načina skrućivanja bila su zapažena (epitaxial i equiaxial). Optimalni parametri zavarivanja su utvrđeni u uskome području. Odabir treba biti prema čvrstoći spojeva, a ne samo prema izgledu

Problems in laser repair welding of polished surfaces

This paper presents problems in laser repair welding of the tools for injection moulding of plastics and light metals. Tools for injection moulding of the car headlamps are highly polished in order to get a desirable quality of the injected part. Different light metals, glasses, elastomers, thermoplastics and thermosetting polymers are injected into the die cavity under high pressures resulting in the surface damages of the tool. Laser welding is the only suitable repair welding technique due to the very limited sputtering during deposition of the filler metal. Overlapping of the welds results in inhomogeneous hardness of the remanufactured surface. Results have shown strong correlation between hardness and surface waviness after final polishing of the repair welded surface

Procjena mikrostrukture alatnog čelika za hladni rad nakon pretaljivanja pulsirajućim laserom

The aim of this study is the investigation of micro-structural behaviour of a Mat. No. 1.2379 (EN-X160CrMoV121; AISI D2) cold work tool steel after remelting with a precise pulsed Nd:YAG laser. The investigated steel is one of the most hard to weld tool steels, due to large amount of alloying elements. The analysis was done on single spots remelted with specific laser pulse shape and parameters, assuring crack-less solidification. Re-solidifi ed areas were investigated with microscopy, hardness measurements, X-ray spectroscopy and diffraction method. Laser treatment causes rapid solidification leading into a formation of a fine dendritic microstructures containing high amount of retained austenite causing a significant decrease of hardness.Namjena ove studije je ispitivanje ponašanja mikro strukture alatnoga čelika za rad na hladno Mat. No.1.2379 (ENX160CrMoV121; AISI D2) po pretaljivanju s preciznim pulsiranim Nd:YAG laserom. Zbog velike količine legirnih elemenata istraživani materijal spada u grupu vrlo teško zavarljivih alatnih čelika. Analiza je provedena na pojedinim pretaljenim točkama korištenjem specifi čnog oblika i parametara laserskog impulsa koji osiguravaju skrućivanje bez pukotina. Pretaljena područja su ispitivana mikroskopom, mjerenjem mikro tvrdoće, rendgenskom spektroskopijom i defrakcijskom metodom. Tretman laserom uzrokvao je brzo skrućivanje koja dovodi do formiranja fi ne dendritičke strukture s velikim udjelom zaostalog austenita što uzrokuje bitno smanjivanje tvrdoće

Pukotine na kalupima (alatima) za tlačno lijevanje uslijed toplinskog umora

Die-casting dies are exposed to high thermal and mechanical loads. Thermal fatigue cracking of dies due to thermal cycling may importantly shorten the life-time of the die. Cracks degrade the surface quality of dies and consequently the surface of castings. In this study, thermal fatigue cracking of dies was analyzed during the process of die casting aluminium alloys. During the process cracks were observed and measured and their location and size were determined. Thermal and mechanical loads cause high local stresses and consequently surface cracks. First cracks occur as early as after 2000 cycles and propagate progressively with cycles.Kalupi (alati) za lijevanje pod tlakom su izloženi velikim toplinskim i mehaničkim opterećenjima. Pukotine uslijed toplinskog umora su zbog izmjene toplinskih ciklusa važan ograničavajući mehanizam životnoga vijeka kalupa. Pukotine smanjuju (degradiraju) kvalitetu površine kalupa i posljedično površinu odljevka. U ovom radu su analizirane pukotine nastale na kalupu zbog toplinskog umora tokom tlačnog lijevanja aluminija. Tokom procesa su promatranjem i mjerenjem utvrđene lokacije i veličine nastalih pukotina na kalupu. Toplinska i mehanička opterećenja uzrokuju velika lokalna naprezanja i posljedično pukotine na površini kalupa. Prva pukotina pojavljuje se već nakon 2000 ciklusa i progresivno se širi povećanjem broja ciklusa