Microstructure and mechanical properties of eutectic nickel alloy coatings

The paper discusses the peculiarities of a structure and a coating composition after reflow. It was established that the structure of coatings from nickel alloy is a solid solution based on nickel, the eutectic of [gamma]-Ni+Ni3B composition and dispersed reinforcing particles. The content of alloying elements in the initial powder material determines the type of the coating structure and the formation of hypoeutectic or hypereutectic structures. The influence of formation conditions on the structure and physical-mechanical properties of the coatings is considered in this paper

Enhancing the Lifetime of Welded Joints Using the Protective Coating and Causes the Formation of Defects in Them

The paper shows the efficacy of eutectic Nickel coatings for protecting welded joints of steels against corrosion. It increases with increasing content of the eutectic and chemical compounds at the grain boundaries γ-solid solution based on Nickel. Refinement of the structure of the coatings and reduce their heterogeneity allows to increase the protective properties and durability of welded joints against corrosion. It is established that the probability of formation of cracks in the coatings increases with their thickness, intensity of heating and cooling after reflow, and also with increasing content of the eutectic and chemical compounds at the grain boundaries γ-solid solution based on Nickel. Shown to prevent the formation of cracks in the coatings when they are melt you can use optimal modes of heating and cooling of the composition. Modification of the structure of the coatings by grinding them and reducing heterogeneity allows to improve the resistance to crack formation and protective properties of welded joints

Improving Processes of Mechanized Pulsed Arc Welding of Low-Frequency Range Variation of Mode Parameters

A new technology of low-frequency modulation of the arc current in MAG and MIG welding is presented. The technology provides control of thermal and crystallization processes, stabilizes the time of formation and crystallization of the weld pool. Conducting theoretical studies allowed formulating the basic criteria for obtaining strong permanent joints for high-duty structures, providing conditions for more equilibrium structure of the deposited metal and the smaller width of the HAZ. The stabilization of time of the formation and crystallization of the weld pool improves the formation of the weld and increases productivity in welding thin sheet metal

The Influence of Modes of Deposition of Coatings on the Corrosion Resistance of Welded Joints of Steels in Acidic Media

In this work, effect of welding on corrosion of welded joints of austenitic steel 12KH18N10T. It is shown that the use of pulsed - arc welding steel 12KH18N10T allows you to create a protective coating with dispersed structure with less thermal impact on the zone of the welded joint. Coating is of such structure allows 1.5 to 6 times to reduce the corrosion rate of welded joints of steel 12KH18N10T in active chemical environments. Pulse the process of deposition of coatings on welded joint of steels can be effectively used for the protection against corrosion in the repair of equipment of chemical industry. The results obtained can be recommended for use when welding a protective corrosion - resistant coatings on working surfaces of equipment of chemical productions

Technology Of MIG-MAG Welds Strength Enhancement

A new technology of MIG MAG welding control is developed. Authors introduce use of power AC and pulse feed of welding wire in the arc zone, that downsizes the heat affected zone, stabilizes formation of electrode metal droplets, as external magnetic field's effect on the arc is reduced. Principal criteria for electrode metal transfer control, when powered by AC sources, are specified

Technology Of MIG-MAG Welds Strength Enhancement

A new technology of MIG MAG welding control is developed. Authors introduce use of power AC and pulse feed of welding wire in the arc zone, that downsizes the heat affected zone, stabilizes formation of electrode metal droplets, as external magnetic field's effect on the arc is reduced. Principal criteria for electrode metal transfer control, when powered by AC sources, are specified