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A method is described to determine geometrical dimensions of electrode metal droplets depending on short circuit duration. It provides a quantitative evaluation of the electrode metal transfer and the energy impact on metal parts being welded. It is proved that using inverter power source decreases the size of droplets transferred to the welding pool by 24% in average if compared with a diode power source. It also reduces overheating of the droplets which improves efficiency of transferring chemical elements from the electrode to the weld metal.

The article presents results of an experimental study and simulation of the effect of welding arc energy characteristics on the nature of electrode metal transfer in MIG-MAG welding. Based on the research results, a method has been developed for determining the coefficient of welding arc plasma flow pressure. The method makes it possible to take into account the dependence of the electrode metal transfer pattern and plasma flow pressure on geometrical dimensions of a welded joint.

Multi-pass laser and laser-arc narrow-gap welding make it possible to obtain high-quality butt joints of large-thickness pipe steels with hardness up to 2600...2800 MPa and toughness close to the base metal toughness at a temperature of 20°C. When multi-pass welding methods are used, the subsequent pass makes heat treatment of the previous ones, and reduces the rate of their cooling yet. This allows excluding heat treatment of the joint after welding, which significantly reduces the time and costs for manufacturing large-sized structures.

The author analyses the changes of heat distribution in welded joints of 30HGSA steel depending on different types of gas shielding. It is determined that thermal cycles in the weld metal and in the heat-affected zone differ depending on the type of gas shielding. In the range of 760...790°С the temperatures level and a hotter metal of the weld becomes less hot in comparison with the metal of the heat-affected zone with any type of gas shielding. The rate of temperature saturation in the welded parts is a little higher with double-jet gas shielding, levelling of the temperatures between the weld metal and the heat-affected metal occurs 1...1.4 seconds earlier than with conventional single-jet gas shielding.

The results of investigations carried out to study the effect of the dynamic characteristics of power sources on the stability of melting and electrode metal transfer to the weld pool in consumable...

In the work the influence of thermal limiters on the formation of a dendritic structure of the stainless steel AISI 304L layer deposited by electric arc welding in argon medium was investigated. The structure of the billets was investigated in the mode of differential interference contrast. The analysis of the obtained structures showed that the use of thermal limiters in the form of graphite skids allows to obtain a uniform structure in billets without sharp transitions between the deposited layers.

In the work, on the example of a coating of a metal-ceramic alloy of 50 vol.% TiC / 50 vol.% (Ni-Cr) of the working part of a die for granulating plastics, the results of the study of the possibilities of using the pulsed electron-ion irradiation method to eliminate continuity gaps in the coating in the form microcracks formed during operation of the die through through the cross section. It has been shown that pulsed electron-ion irradiation makes it possible to restore the integrity of metal-ceramic coatings by filling cracks with a melt of a nickel-chrome binder metal-ceramic composition extending to the surface of the coating of cracks to a depth of more than 100 μm.

In the given paper we consider the impact of wind velocity upon the active shielding gas flow and changes of thermal processes in the MAG welding area. The authors completed numerical simulation of consumable electrode welding under traditional and two-jet gas shielding. It was established that application of two-jet gas shielding for MAG welding increases the hardness of the shielding gas jet and reduces wind-related displacement of thermal fields in the welded item. This ensures more qualitative shielding of the welding area under the windy conditions and uniform heat distribution in the welded item which leads to more homogeneous structure of weld and HAZ metal in comparison to the traditional (one-jet) gas shielding.

The paper presents the results of studies improve efficiency of manual arc welding of austenitic steels. It is in arc welding of austenite steels the use of inverter power supply furthers obtaining more fine-grained structure of added metal and thermal impact zone, shortens thermal impact zone; that improves corrosion resistance of joint weld.

The influence of the welding current and method of gas shielding in MAG welding on the content of silicon and manganese is considered. Results of study of the welded specimens of steels 45 and 30HGSA when applying welding wire of different formulas and different types of gas shielding (traditional shielding and two-jet shielding) are given. It is established that in MAG welding the value of the welding current and the speed of the gas flow from the welding nozzle have a considerable impact on the chemical composition of the weld metal. The consumable electrode welding under double-jet gas shielding provides the directed gas-dynamics in the welding area and enables controlling the electrode metal transfer and the chemical composition of a weld.

In the paper the authors provide the method for calculating the heat content of the molten electrode metal droplets according to the energy parameters of the power supplies for manual metal arc welding. It was established that the type of the welding power supply has a significant impact upon the temperature, mass and active surface area of the electrode droplets.

The paper provides the results of experimental study of how the technological characteristics (amount of spatter, stability of the welding process) of manual metal arc welding (MMA) depend upon power supplies providing various kinds of energetic impact upon the electrode metal (inverter power supply, diode rectifier). It was established that inverter power supplies (as they reduce peak loading) provide better quality of welds (more stable process, lower amount of spatter) and this reduces the fabrication cost due to the reduction of deseaming operations, lower welding material consumption as well as improving the service reliability of the welding constructions.

A set of various factors and phenomena defines the quality of welded joints. This is especially noticeable for outdoor welding. A numerical simulation of welding processes with consumable electrode with traditional and two-jet gas shielding was carried out to study the influence of wind speed on the movement of the shielding gas (CO2) and the change of thermal processes in the heat affected zone. It is established that the use of two-jet shielding in welding with a consumable electrode leads to an increase in hardness of the shielding gas stream and lower offset of thermal fields in the welded product in the wind direction. It testifies to a better quality of shielding and smaller probable changes in symmetry of structure formation and mechanical properties of the heat affected zone.

The given work considers the influence of the power supply type (diode rectifier DR-306 and inverter Nebula-315) upon the chemical composition, microstructure, mechanical properties of weld joints and upon health characteristics of the manual arc welding process.It has been ascertained that the power supply type has a significant influence upon the weld joints properties and health characteristics of the manual arc welding process. Using a new generation inverter power supply allows less heat input into the weld bead, thus, decreasing silicium and manganese burning, improving impact resistance of weld joints under low (negative) temperature and reduces the risk of respiratory diseases for the workers.

The processes taking place in a drop of a molten electrode metal and in a metal of a weld pool play the dominant role in formation of joint welds properties. In consumable electrode welding with jet gas shielding under certain conditions a drop of an electrode metal is influenced by the main forces as well as by the force of a shielding gas jet impact which depends upon the method and composition of a gas shielding in a welding area. The results of research have stated that the force of a shielding gas jet impact on a drop of an electrode metal in double-jet gas shielding is twelvefold as in one-jet one; it is directed along the electrode to a workpiece and stimulates stability of the electrode metal drops transfer into a weld pool.

A combination of various factors and phenomena determines the quality of the welded joints. The basic role in setting the properties of the welded joints belongs to the processes taking place in the drop of the melted electrode metal. The paper considers the influence and vector components of the basic forces on the melted metal drop in gas jet shielded welding a moment before the drop transfers from the electrode to the weld pool. Methods of calculating the force exerted by a shielding gas jet on the drop of the electrode metal and subject to its dissociation are offered. The frequency and stability of drop transfer to the weld pool increase with the growth of the shielding gas impact force on the electrode metal drop in double jet gas shielding.

Controlling the processes, which take place during consumable-electrode shield-gas welding, is one of the main problems of the welding industry. The paper shows that under the certain conditions the electrode-metal drop and heat distribution in the weld area are influenced by the active shielding gas jet. The paper provides the results of modeling heat distribution in the weld area and active shielding gas outflow from the traditional and double-jet welding torch nozzles.

The given work considers the influence of the power supply type (diode rectifier ВД-306 and upon new generation inverter Nebula-315) upon the chemical composition, microstructure, mechanical properties of the weld joints and health characteristics of the manual arc welding process.

The possibility of using thermal imaging equipment (a thermal imager) for determining the pattern of the temperature field distribution on the surface of welded items is considered. This allows evaluation of a region that is subjected to thermal action in the real-time mode and predicting the strength characteristics and the chemical composition of the welded joint.

The given article studies the changes in thermal cycle and cooling rates of steel 30ХГСА weld joints at various distances from the weld center using modern thermal imaging equipment. The analysis of the experimentally obtained and calculated thermal cycles showed that the calculated cycles almost match the experimental ones in terms of quality but the time distribution of calculated values is 4-5 times smaller than that of the experimental ones. On the base of experimental results and theoretical investigation of the thermal cycles for fusion-welding in СО2 we have developed an improved formula for calculating heat conduction for machine single-pass welding. The difference between the calculated and experimental values of thermal fields does not exceed 10%.

The paper considers the ways of weld geometry controlling when consumable electrode welding under single-jet and double-jet gas shielding. The authors provide comparative results of experimental studies on the effects of shielding gas supply upon the weld geometry in weld joints produced from construction carbon steel 45. It has been established that gas-dynamic effect of the shielding gas has a significant impact upon shaping and weld geometry when consumable electrode welding under double-jet gas shielding.

In the paper we present the results of the study of the power supply characteristics effect upon the stability of electrode metal melting and transfer into the weld pool in the process of consumable electrode welding. It was shown that application of inverter type welding power supplies of the new generation results in changing the characteristics of the heat and mass transfer which has a decisive impact upon the heat content of the weld pool, reduction of residual stresses in the heat-affected zone (HAZ). The authors also substantiate the tendency to the reduction of the structural constituents in the area of the permanent joint.

The paper presents results the research in the effect of power sources dynamic characteristics on stability of melting and electrode metal transfer to the weld pool shielded metal arc welding. It is proved that when applying inverter-type welding power sources, heat and mass transfer characteristics change, arc gap short-circuit time and drop generation time are reduced. This leads to reduction of weld pool heat content and contraction of the heat-affected zone by 36% in comparison the same parameters obtained using a diode rectifier.

The article presents the results of experimental studies showing that the use of an inverter power supply instead of a diode rectifier provides:: fine-droplet electrode metal transfer which reduces generation time by 46% and transfer time by 28%; transfer of alloying elements from welding materials into the weld metal which reduces its loss from the welding line by 6% and the heat affected area by 3%; reducing the emission rate of welding fumes and their components by 23%; reducing specific emission of welding fumes and their components by 23%.

In the context of a significant increase in production output and use of welding technologies in the manufacturing of engineering products the problem of hygienic characteristics of working conditions in arc fusion welding is becoming increasingly important. The work represents how the dynamic characteristics of a power supply affect the transfer of alloying elements from a coated electrode into a base metal, a slag phase and a solid component of welding fumes. Short-circuit current limiting in inverters reduces overheating of electrode metal drops by 15%; welding fumes quantitative component - to 38%; manganese - to 30%; thermal radiation intensity - by 37%.

Chemical composition of weld metal and properties of a joint weld are dominated by the processes occurring in the drop of molten electrode metal and in metal of the weld pool. Under certain conditions in consumable electrode welding with jet gas shielding the drop of electrode metal is influenced significantly both by main forces and the force of gas-dynamic impact of the shielding gas jet. The results of research have revealed that changing rate of shielding gas flow on the nozzle section influences the processes taking place in the welding area. There are changes in the transfer frequency of electrode metal drops and chemical composition of weld metal.

The influence of the welding current and method of gas shielding in MAG welding on the content of manganese is considered in the paper. Results of study of the welded specimens of steels 45 when applying welding wire of different formulas and different types of gas shielding (traditional shielding and double-jet shielding) are given. It is found that in MAG welding the value of the welding current and the speed of the gas flow from the welding nozzle have a considerable impact on the chemical composition of the weld metal. The consumable electrode welding under double-jet gas shielding provides the directed gas-dynamics in the welding area and enables controlling the electrode metal transfer and the chemical composition of a weld.

The paper outlines peculiarities of structure formation, phase and chemical composition in regard to heat content in molten electrode metal beads when pipe steel (steel 09G2S) welding using power sources with various energy characteristics. Mathematical calculations indicate an inverter power source provides minor heat content into the bead of electrode metal when welding. Experimental research has pointed at 4-9 % increase in impact strength of joints produced using an inverter power source in comparison with samples produced applying a diode rectifier. The following factors can possibly give rise to the increasing impact strength: difference in microstructures of weld joints, up to 50% shortening ferritic plates in metal of weld joint, change in dimensions of ferritic grains in the heat-affected zone by as much as 17.5 %, and decrease in the extent of heat-affected zone by 50%.

The author considers gas-dynamic influence upon microhardness and weld configuration of single-pass welds from steel 30HGSA when welding with consumable electrode under double-jet shielding. The relations to the chosen controlled welding parameters (Q, L, I) are developed and the controlling influence of the gas-dynamic affect of dynamic shield gas jet over formation of welds from alloy-treated steel 30HGSA is determined.

The study of health and safety characteristics of manual arc welding with coated electrodes from power sources of various types (inverter converter, diode rectifier) allowed to find that application of inverter convertors improves sanitary-hygienic work conditions of the welder's work.

The characteristics of heating processes determine fusion efficiency for base metal and filler material, direction and completeness of metallurgical processes in a welding pool, formation of weld metal structure and heat-affected zone, service properties of welded joints. Under certain conditions in consumable electrode welding with jet gas shield an electrode metal droplet and processes in the weld zone are influenced by the force of shielding gas jet besides the main forces. Significant influence of this force is noted in CO 2 double-jet gas shield. Basing on the research results it was determined that distribution of heat in the electrode, fused metal droplet, arc space, welding pool and parts being welded depends on the shape and velocity of active shielding gas flow.

This work presents peculiarities of forming a structure, phase and chemical composition while welding medium-carbon steels (Steel 45) depending on a heat content of molten electrode metal droplets when using welding power sources having different power parameters. It was experimentally established that the power inverter provides the decreased heat input into droplets of electrode metal during the welding process. This stimulates obtaining a fine-grained structure of the deposited metal and heat affected zone, reduces the extent of the HAZ that enhances working properties of welded joints.

In these conference proceedings we present papers from the 6th International Scientific Practical Conference on Innovation Technology and Economics in Engineering held at the Yurga Institute of Technology branch of the National Research Tomsk Polytechnic University from 21st – 23rd May 2015. The proceedings contain the selected scientific reports submitted to the conference. Having started in 1996, the scientific conference at the Yurga Institute of Technology branch of the National Research Tomsk Polytechnic University acquired international status in 2010. This year, scholars from Russia, Kazakhstan, Belarus, Ukraine, Azerbaijan, China, Germany and Poland have submitted their papers to the conference. The scientific reports published in these proceedings have been revised and approved by the editorial team of the conference. All of the reports exhibit clear, concise, and precise expositions that appeal to a broad international readership interested in mechanical engineering, welding, metallurgy, materials science as well as in computer-aided manufacturing and economics. The reports present original ideas or results of general significance supported by clear reasoning and compelling evidence, and employ methods, theories and practices relevant to the research. The authors state clearly the questions and the significance of their research to theory and practice, describe how the research contributes to new knowledge, and provide tables and figures that meaningfully add to the narrative. The organizing committee of the conference thanks all the participants for their fruitful work and personal contribution to the development of these conference proceedings.