This paper addresses the metallurgical and mechanical characterization of dissimilar joints made by laser autogenous welding between thin sheets of low-carbon steel (CS) and austenitic stainless steel (SS). The welding technology applied, previously optimized to produce sound dissimilar joints, is based on the heat source displacement from the weld gap centerline towards CS, in order to reduce the SS overheating. The research includes optical microscopy observations, energy dispersive X-ray analysis (EDX) to assess the wt% of Cr, Ni, and Fe in all regions of the dissimilar welded joint, hardness measurements, and tensile tests of transverse-welded flat specimens. In comparison with classical determination of the joint overall mechanical characteristics, the novelty of this research consists of experimental assessment of the local mechanical behavior of the fusion and heat affected zones by using a digital image correlation technique (VIC-2D). This is an efficient tool for determining the constitutive properties of the joint, useful for modelling the mechanical behavior of materials and for verifying the engineering predictions. The results show that the positive difference in yielding between the weld metal and the base materials protects the joint from being plastically deformed. As a consequence, the tensile loading of flat transverse specimens generates the strain localization and failure in CS, far away from the weld.

Wire arc additive manufacturing (WAAM) is a fusion manufacturing process in which the heat energy of an electric arc is employed for melting the electrodes and depositing material layers for wall formation or for simultaneously cladding two materials in order to form a composite structure. This directed energy deposition-arc (DED-arc) method is advantageous and efficient as it produces large parts with structural integrity due to the high deposition rates, reduced wastage of raw material, and low consumption of energy in comparison with the conventional joining processes and other additive manufacturing technologies. These features have resulted in a constant and continuous increase in interest in this modern manufacturing technique which demands further studies to promote new industrial applications. The high demand for WAAM in aerospace, automobile, nuclear, moulds, and dies industries demonstrates compatibility and reflects comprehensiveness. This paper presents a comprehensive review on the evolution, development, and state of the art of WAAM for non-ferrous materials. Key research observations and inferences from the literature reports regarding the WAAM applications, methods employed, process parameter control, optimization and process limitations, as well as mechanical and metallurgical behavior of materials have been analyzed and synthetically discussed in this paper. Information concerning constraints and enhancements of the wire arc additive manufacturing processes to be considered in terms of wider industrial applicability is also presented in the last part of this paper.

The maintenance and repairing actions for underwater metallic structures from maritime and offshore field are usually achieved using the gas metal arc welding processes. The welding processes applied should take into consideration different underwater conditions, and experiments should be conducted for different pressures. In the first part of the study, the authors focused on the investigation of the EH 36 shipbuilding steel behaviour subjected to dry hyperbaric metal active gas (MAG) using semi-automatic welding devices. Hereinafter, the authors analyse, by using the electrochemical method, the behaviour of the welded joints to marine corrosion. In the last part of the investigation, the corrosion influence on the roughness of the specimen’s surfaces, depending on the potentiodynamic polarization curves, is approached. The experiments revealed that increasing of pressure conditions leads to an increased corrosion resistance and moreover, to a decrease of the specimen surfaces roughness.

The study presents in the first part the behavior of the EH 36 steel with the thickness of 10 mm to MAG mechanized welding of butt-welded joints from the naval field, destructive and non-destructive testing for all welded samples. Furthermore, corrosion of the marine environment is analyzed by the electrochemical method. The study is completed with the corrosion influence on the roughness of the welded joints surfaces and conclusions.

The paper presents the experimental research on the behaviour of EH 36 naval steel at the MAG-M mechanized butt welding in the naval field. Butt welded joint was performed in the four welding positions (PA/1G, PC/2G, PF/3G and PE/4G). In the welding process, two types of tubular wires and a mixture of active protective gases were used. The first part of the paper presents the effective welding of the four samples. The results of the nondestructive and destructive controls of the welded samples are presented below. The work is completed with the conclusions drawn from the experimental program. The good results thus obtained make it possible to apply the welding technologies of the EH 36 naval steel in the four analyzed positions.

In this paper we analyze the corrosion behavior of the MAG-M mechanized butt welding with metal-cored wire and rutile flux-cored wire at two welding positions PA and PC at in situ conditions of the Black Sea. The following materials were used in this experimental programme: base material (high strength steel sheet EH 36, dimensions 300 x 150 x 10 mm), filler material (metal cored wire (E70C6MH4) and rutile flux-cored wire (E71T1MH4) according to AWS A5.18, diameter 1.2 mm) and auxiliary materials (M21- Corgon 18 gas mixture and flat concave channel ceramic support). The samples were immersed in sea water harvested in the Black Sea and then subjected to corrosion tests by electrochemical methods.

The thermal field has a major influence during the welding process. The heat transfer resulting from welding has an influence on the metallurgical and mechanical properties of steels and welded joints. The most affected regions are: fusion zone (FZ) and heat affected zone (HAZ) due to high temperatures to structural transformations of welded joints. The research is based on the theoretical investigations on high-temperature welding areas through MAG-M mechanized butt welding with solid wire of the naval high strength steel, EH 36. For theoretical research, a model with 3D finite elements was used. For the welded joint, the filler technique was used, which means the filler material is modelled with finite elements. The finite elements are activated when the heat flow passes through them.

Selecting the appropriate welding technique, the optimum parameters and the proper welding wire - shielded gas couple, the gases and fumes can be reduced and, consequently, the risks for the welder's health and the impact on the environment are diminished. The main goal of this research was focused on the evaluation of carbon monoxide concentration and of microparticles amount that are produced during Metal Active Gas Welding, Flux-Cored Arc Welding and Metals-Cored Arc Welding processes, using different filler metals and applying different feed wire speeds. Eleven wires (solid, basic and rutile flux-cored, low fume flux-cored, metal-cored, low fume metal-cored), in combination with shielding gas such as carbon dioxide or Corgon 18, a two-gases mixture of carbon dioxide and argon, have been used in the experimental research. Combining the wire type, the shielding gas and modifying the wire feed speed, forty-five samples were performed by deposition welding. The experimental data in terms of carbon monoxide concentration and microparticles amount produced during welding were processed and comparatively discussed. The investigations revealed that the lowest risk on the welder's health and the lowest impact on the environment are achieved during Metal-Cored Arc Welding with low fume metal-cored wire and Corgon 18 shielding gas.

The paper presents a comparative analysis related to the melting and deposition characteristics of different welding wires of 1.2 mm diameter, such as solid (ER70S6), basic flux-cored (E70T5CJH4), rutile flux-cored (E71T1MH4), metal-cored (E70C6MH4), and low fume metal-cored (E70C6MH4) used in Metal Active Gas Welding, Flux-Cored Arc Welding and Metal-Cored Arc Welding. Two-gases mixture, comprising 82% argon and 18% carbon dioxide, known as M21 (Corgon 18) shielding gas, was used during experiments to protect the contamination of the molten weld pool against oxygen, nitrogen, and hydrogen. Five weld beads have been deposited on S275N steel sheets in horizontal welding position (1G/PA), by employing the filler metals mentioned above. Based on the experimental results and comparative analysis, significant information on melting and deposition characteristics has been achieved. The experimental results have revealed that the lowest loss ratio was achieved in the case of MCAW with low fume metal-cored welding wire (E70C6MH4).

During the welding process, the filler wire - shielding gas couple generates the formation of pollutants which are dangerous for the welder's health. The research focussed on the quantitative evaluation of carbon monoxide (CO) and microparticles concentrations produced in MAG-C (Metal Active Gas-CO2) welding in various process conditions. Seven welding filler wires - one common solid wire, one basic flux-cored wire, three rutile flux-cored wires and two low fume rutile flux-cored wires- were selected for the investigation and comparative analysis of the pollutants developed by melting of these wires which were deposited by welding on EH36 shipbuilding steel sheets. Applying consecutively three feed rate values, twenty-one seam welds were performed in welding horizontal position within a special hermetically air-tight chamber. Concentrations of CO and microparticles were acquired through special devices - Multilyzer NG of gases and MicroDust Pro for microparticles - and then were processed and comparatively discussed. Using SEM analysis, measurement of particles' size was made and discussed in detail. The images obtained by SEM illustrated the formation of amorphous structures and also nano and micro-sized particles with diameters from 641,1 nm to 8,92 μm. The investigations revealed that the lowest concentrations of CO and microparticles were produced when solid and low fume rutile flux-cored wires were used in the deposition welding.

Exposure of welders to welding fumes and microparticles produced during electric welding can be dangerous and may cause serious maladies. It is important to understand the formation mechanism of microparticles generated during welding process on the one hand and the methods to diminish the risk on the welder’s health on the other hand. Experimental research results related to the assessment of microparticles size, generated during MAG welding process, are presented and discussed in detail in this paper. Rutile flux-cored and low fume metal powder cored wires with 1.2 mm diameter in combination with CO2 shielding gas or M21 gas mixture (Corgon 18) have been used in the investigations. The experimental tests were performed in a special enclosure, equipped with Glass Fiber Filters and a Philips vacuum, with the aim to capture the microparticles developed by the MAG welding process. The microparticles collected during the experimental program have been analysed and measured by electron microscopy method with (SEM/ESEM - EDAX) Quanta 200 microscope. The study showed that low fume metal powder cored wires determined the achievement of smaller microparticles in comparison with rutile flux-cored wires. Finally, several conclusions emerged from the findings of this study are synthetically presented.

It is well known that CO and microparticles generated during GMAW welding processes can affect the welder's health and the environment quality and should be avoided. The main goal of the research was to quantitatively assess the concentrations of CO and microparticules resulting through melted wire - shielding gas - welding pool interaction, specific to fusion welding process, in particular MAG-M (Metal Active Gas with Corgon shielding gas)) process. The concentrations of microparticles and emission of CO developed by several combinations of filler metal and shielding gas, such as ordinary solid wire, basic flux-cored wire, rutile flux-cored wire, metal powder cored wire, low fume metal powder cored wire and Corgon 18, as shielding gas mixture, have been monitored and investigated in detail. The experimental data, achieved for different wire feed speed values, were collected by using special devices as Multilyzer NG and MicroDust Pro and further processed, plotted and comparatively analysed. The analysis revealed that the low fume rutile flux-cored wire significantly developed lower concentrations of microparticles and CO, in comparison with the other types of wires used in MAG-M welding process, and a better protection of the environment would be achieved. Important conclusions related to the influence of the wire type on the concentrations of CO and microparticles produced during MAG-M welding process have been drawn and some recommendations useful for the producers of welded structures are provided at the end of the paper.

In the case of the MAG welding of carbon and low-alloyed steels wires or hollow wires with (rutilic or basic) flux with metallic powder or self-protection are used. In indoors weldings huge quantities of smoke, gases, dust and particles in suspension, etc. get accumulated. These noxious substances produced during the welding process may severely affect the welders health. To improve the welders working conditions, on an international scale, the following are used: welding masks with self-obscurazation and air control; noxious substances vacuum cleaners fitted with filters; MAG welding pistols with gase and smoke absorbing devices. For the improvement of the welders working conditions, producers of welding materials invented hollow wires with (rutilic flux or with metallic powder) with a smoke-reduced emission [1,2,3,4,5].

The statement from the specialty literature that with the increasing diameter of spot welded by cold pressure decreases the amount of resistance to shear force is due to reporting of the breaking by shear at the circular section of the point. Our experimental research shows that a welded cold joint in spots, correctly done, will be torn off near the weld spot by drawing the point from one of the tins. By reporting the force to the real section of breaking it resulted a constant shear resistance, no matter which the size of the welded point was. Therefore, the approximate theoretical calculation of the breaking force of a cold welded point, correctly executed, can be achieved by knowing the mechanical properties of the metal base and taking into account the real section of the breaking point given by points periphery and the thickness of the panel after deformation. The calculation is encompassing, because due to cold hardening, the real mechanical characteristics are higher.

Use of cored wire - shielding gas (gas mixture) pair, during mechanized MAG welding, causes the microparticles formation which is harmful for the welder’s health. The paper presents the experimental method for determining the concentration of the microparticles generated during MAG welding when rutile cored wires (standard and low fume emission) and metal powder cored wires (standard and low fume emission) are used. Carbon dioxide and the shielding gas mixture are investigated, too. Four types of cored wires were comparatively analysed, when three wire speed values were applied. The research of the microparticles concentration was conducted after each welding bead deposition, at the upper part of the welding enclosure, using MicroDust Pro particulate monitor. After each weld bead was deposited, the metal frame of the welding enclosure was removed, and, the fumes and gases, produced during the welding process, were eliminated through two fans, positioned inside and outside of the equipment. Using rutile cored wire with low fume emission, a decrease of microparticles concentration up to 30% is noticed in comparison with standard rutile cored wire. Using metal powders cored wire with low fume emission, the microparticles concentration is diminished with 12.5% comparing with standard metal powders cored wire.

The paper presents experimental research concerning the mechanized MAG-C welding using rutile cored wire (standard - Fluxofil 14HD a nd ecological - Cristal F100) with diameter of 1.2 mm and CO 2 as shielding gas. A universal welding source Arist o Lud 320 and a welding tractor Railtrac FW 1000 were inc luded in the configuration of the experimental stand. Experimental samples were butt welded on flat ceramic support, on vertical ascending position PF (BW). The technologi cal parameters of the welding regime, the control of butt welded samples and labo ratory mechanical test results are presented in this work. Some conclusions related to the presented experimental researches are emphasized in the end of the paper.

The paper presents the determination of the coefficient of fusion and of the weld deposition coefficient at mechanized MAG welding using rutile flux cored wire (standard - Fluxofil 14HD and ecological - Cristal F100), having diameters of 1.2 mm. During the experiments, CO2 has been used as shielding gas. The experimental stand is equipped with the universal welding source Aristo Lud 320 and the welding tractor Railtrac FW 1000. The two welding beads have been deposited on metal plates in horizontal position (1G/PA). In the paper, there are presented, in tabular shape, the experimental results of measurements and the calculated values of the coefficients of fusion and of weld deposition. The final part of the article is dedicated for the conclusions of the study.

This paper refers to the influences of the welding technological parameters (feed rate of the wire - v(e), welding speed - v(s) and welding voltage - U-a) upon the dimensions of the HAZ. Within this study there has been used the mechanized MAG welding with rutile flux cored wire (standard - Fluxofil 14HD and ecological - Cristal F100), having diameters of 1.2 mm. During the experiments, CO2 has been used as shielding gas. The experimental stand is equipped with the universal welding source Aristo Lud 320 and the welding tractor Railtrac FW 1000. The two welding beads have been deposited on plates in horizontal position (1G/PA). HAZ dimensions have been established on samples taped transversally on the welding direction, after grinding and adequate metallographic preparing. The paper presents the program of experimental research together with the results and the final conclusions.

This paper contains the establishment of the reshuffle technology by the process of welding the parts cast of magnesium RZ5. These alloys are used frequently in the automotive industry. In the first part of the paper there are presented the performances, the influences of the main alloying elements and the welding behaviour of the magnesium alloys. Furthermore it is presented the experimental program and the un-destructive and destructive control of the submissions. The paper ends up by presenting the final conclusions.