Advanced Materials Research Vol. 1029

Abstract: Weldability of magnesium alloy to aluminum alloy in laser weld bonded (LWB) joints are investigated. Results showed that magnesium/aluminum could be easily joined by LWB under proper technological parameters. The weld is characterized by complex vortex flow at the bottom and there existed intermetallic compound layer between weld pool and lower sheet metal which was composed of the brittle phases of Al₃Mg₂. The aim of this research is to evaluate the weldability using LWD process to join Mg/Al alloys using HLD 3504 – Laser Type Trumpf, to explain the experimental conditions and interpretation of results.

Abstract: At present, in the automotive industry, the trend on the world plane is to fit on the wheels with rims made from nonferrous alloys, based on aluminum, magnesium or titanium. These rims have the advantage that they are lighter than the same rims made from steel, reducing the unsprung mass of the vehicle, and increasing the vehicle performances, that lead to the better handling, the faster braking and the better acceleration. Also, by using the rims made from nonferrous alloys, the increasing of the fuel consumption efficiency and the reducing of the carbon monoxide (CO) emission are obtained. During the traffic, the wheels (rim + tyre) can be subjected to accidental collisions, such as the impact with the pavement, leading to damages of the rims, which must be reconditioned. The paper presents the results of structural examinations and mechanical tests, made on car rims made from nonferrous alloys, degraded and reconditioned by specific welding technologies. The structural and mechanical characteristics determined in the zones reconditioned by welding are at the level of the base metals used to made the investigated rims, that confirm the adequate quality of them, and a low risc to cracking.

Abstract: The mechanical tenacity characterizes the materials behaviour to static and dynamic shocks, at the ambient and the negative temperatures. In the case of deposited metals by welding, the tenacity characterization is made by determining the impact energy, (KV), the crack back contraction, (CBC), the lateral expansion (EL), and the correlation between these characteristics.

Abstract: The paper presents research conducted for the development of precursors and wrapped rods for brazing, that deposit, through melting, two different alloys, with respect to the level of silver alloying and the melting temperature. The alloy with the high silver content is introduced under the form of powder, in the coating of the brazing rods, in a participation proportion that assures a buffer layer, with advance proprieties of diffusion in the base metal and in the core alloy of the coated rod. The participation ratio of the silver rich powder alloy is established within the following limits 8-12%, depending on their melting point, the grinding degree and mixing with the deoxidizer coat. The development of the precursors was made by homogeneous melting and spraying on a oblique plan, the grains obtained were grounded, the grist obtained is considered optimum to be introduced in the coating mixture after it successfully passed through a sieve with a mesh of 0.1 mm. The alloyed precursors with 45% silver, grounded between the above mentioned limits, were introduced in the deoxidizer coat mixture af the bare rods type Ag30 according to SR EN 1044/1999. The resulted mixture was used to manufacture experimental lots of covered rods for brazing, which were used for testing, in order to achieve highly important joints. The melting temperature of the precursors was established through micro-alloying so that it will be 10-15°C higher than that of the deoxidizer coat, which in turn has a lower melting temperature, by 56-60°C, than the melting temperature of the core alloy. The deoxidizer coat is usually fluoroboric type, conforming to SR EN 1045/2001. Representative joints made with the new experimental rods, after testing, presented results consistent with the requirements, which allowed the authors to appreciate this method as appropriate for cost reduction with brazing materials in the use of composite coated rods.

Abstract: The rigorous stress conditions of active surfaces, from the components of magmatic rock processing equipment of surface pits, required finding new materials and system processes that achieve major impact on wear processes, in the sense of decreasing them. Conducted research with classic cladding by welding materials showed a high importance of the chromium carbides in the deposits, in the fight against wear. From manufacturing considerations, the participation of chromium carbides in the deposits made with traditional welding materials is 35%, which required finding new ways to obtain superior performances.The group of authors considered the nanostructure method to be convenient, hence of finishing the deposition structure, by introducing in the cladding by welding material composition centers of crystallization with colloidal size and superior temperatures, compared to the molten through welding bath temperatures. In order to achieve a new generation of cladding by welding materials, we proceeded to develop, on the above mentioned principle, rods that deposit by welding alloys like Fe-20%Cr-4%W-1%Ti, nanostructure with melted tungsten carbides and colloidal grinded. The rods thus obtained were used for cladding active surfaces of general purpose extraction and processing machines for basaltic rocks, to achieve highways.Results obtained confirm theoretical assumptions, which led to the implementation of new products in the industrial production.

Abstract: During the years a number of different simulators have been developed for the welding community. These simulators have been targeted to different user groups and different technical level of the group itself. The technological quality has mostly been on a professional level, although the user friendliness, we must admit, may have a wide interpretation of the word “friendliness”. The use of mobile devices, pads and so forth, with other interface methods than the keyboard, that has appeared over the last years have given us new opportunities to define user interfaces that are completely different from what was possible before. This paper will discuss a work in progress for a simulation project development related to education and training, in two different projects, IWSD (Leonardo da Vinci project) and Green Weld (EEA Grant project), currently running in Romania and in Bulgaria.

Abstract: The issues from the last decades related to the crisis of natural resources, raw materials, equipment, energy etc., gave rise to a new concept, namely sustainable development. The theory of sustainable development focuses on the development of quality products to provide trust and confidence, so as reliable. On this line the paper presents an approach on assessing the reliability and non-reliability of the milling teeth for asphalt machines classic manufactured and those manufactured by welding load, which give them self wear protection systems and self-lock at rotation. So in this sense there are presented comparative estimates regarding to the operating lifetime of the four batches of milling teeth for asphalt, 41Cr4 mark steel (EN 10083-1) the classic version and 3 groups of teeth load by weld on their working surface(wear) by different welding methods, namely: WIG - with filler material type tubular wire FILEUR DUR 606B, WIG – filler material with tubular type VT2, 5CrTiD rods, and MIG/MAG (CMT), the tubular wire filler material type FILEUR DUR. So, asphalt milling machines were stripped with 4 groups of teeth in order to track the behaviour during exploitation of each batch. Assuming that the product specifications properly respond customers' requirements, the level of reliability can be measured accurately by the fraction of delivered units that meet the specifications. On this line for estimating the reliability the Monte Carlo simulation method was used, which is suitable for analyzing the products that are designed to provide superior quality.

Abstract: In the production of steel parts exigent of high durability to abrasive wear at high temperatures and / or corrosive environment, the method is used for the deposition welding with the addition material MSG-6-GZ-C-60G. With this material layer it is made of 55-60 HRC hardness, corrosion and wear resistant, with properties that are kept up to temperatures of 5000 C. There can be manufactured new parts (pressure casting forms, components for dies, molds, etc.), or dynamically and abrasion-torn reconditioned parts may be required. Deposits have been made with wear-resistant layer on the steel 42CrMo4, with and without the generation of vibration during welding. For the samples swing, a device was used with an electrodynamic exciter to generate vibrations with frequencies up to 20 kHz. Vibration tests were performed at a frequency of 50 Hz, because the frequency can be applied in industrial conditions, by means of excitation of electromagnetic or vibration driven motor. There have been registered horizontal and vertical accelerations which lead to changes in the conditions of crystallisation of the melt, respectively the formation of a microstructure with superior features. Microstructures and hardness recorded on specimens welded with and without vibration are comparatively presented. Micrographs which were made demonstrate the favourable influence of the vibration on the quality of the deposited layer and the base material. Whith the vibration with accelerations of a_x = 55 m/s² and a_z = 70 m/s² resulted: much lower deformation of the base material, HAZ - a lower content of residual austenite, in the TZ there was a great interlock of the two materials, in the deposited material the dendritic crystals strongly fragmented and the grain was finished.

Abstract: The manufacture of pipelines is a complex technological process starting with laminates supply, joints cutting-processing, rolling, welding, calibration, control, packing, delivery. As a rule, the technological welding process is achieved by welding on generators through MAG and submerged arc welding, procedures which generally take place completely automatically, affecting the quality and cost of products. Beside a series of advantages, submerged arc welding also has disadvantages; it does not eliminate the operator’s intervention and implies some high linear energies with implications on the mechanical-metallurgical characteristics of the welded joints. In this paper we present the preliminary results of the experiments which have been carried out on welded joints on X52 steel plate, g = 12 mm, through classical MAG welding, with one wire - filler material on the first layer, and the filling beads through tandem MAG welding, with two wires. We should mention that the plates had a V(30°) joint and the welding was executed unilaterally, horizontally, the wire - filler material being of the same quality G42 4 M G3 SI1 ( EN ISO 14341) and diameter (1.2 mm), and EN ISO 14175 protection gas. The entire technological welding process was carried out in laboratory conditions, fully robotized, using a QIROX-315 welding robot fitted with QUINTO-GLC 603-type tandem MAG welding installations, owned by ICDT-PRO-DD C12 “Advanced welding eco-technologies”, belonging to Transylvania University of Braşov.

Abstract: Aluminum silicon alloys, the 4xxx group of the aluminum alloys, are mostly processed into cast parts. As for other cast designated alloys, their weldability is often considered as an unimportant feature. The interest, if any, is almost completely related to the repair welding.The present work analyses how silicon particle dimensions, which depends mostly on the silicon content into the metallic matrix, affects the weld properties. Also it is revealed the HAZ metallographic aspect for two frequently welding processes used on aluminum alloys, TIG and FSW. Friction welds resistance is better than that of the TIG welds, associated with a lack of symmetry (retreating side versus advancing side).Silicon particles diminish their dimensions for hypo eutectic or eutectic concentrations; for hyper eutectic compositions the effect has an almost unimportant effect.