No abstract

No abstract

Peculiarities of heat input, bead cross-section area and efficiency were investigated at single-layer microplasma powder surfacing of nickel heat-resistant alloy JS32 on narrow substrate of 1-2 mm thickness. It is determined that series of its modes using 5-15 A welding current differs by the minimum heat input. calculated evaluation of stress-strain state of a welded joint was carried out for its minimum and maximum level during building-up of edge of a plate using single-and three-layer surfacing. It is shown that the value of heat input in microplasma surfacing determines a width of plastic deformation zone and value of sum plastic deformations as a result of reheating in multi-layer surfacing. New technological principles were proposed for selecting the modes of multi-layer and 3D-microplasma powder surfacing of the parts from nickel heat-resistant alloys, providing the minimum heat input in a part and regulating requirements to welding current value, time of existence of metal of weld micropool in molten state and its volume. 20 Ref., 2 Tables, 10 Figures.

No abstract

Heat-resistant nickel alloys are the main structural materials used to manufacture gas turbine engines widely applied in aircraft engineering and other industries. Engine sections for high-temperature operation are made using precipitation-hardening nickel alloys with intermetallic strengthening. To ensure the structure stability and maintain high long-term strength properties, nickel alloys are provided with complex alloying systems containing γ'-forming elements (Al, Ti, Nb), the total content of which in an alloy amounts to 6-15 % or more. Complex alloying systems and high strength properties of the alloys lead to crack formation in the weld and heataffected zone in welding metal of even small thickness. This stipulated the interest in investigating the principles of hot crack formation first of all in the heat-affected zone during fusion welding in terms of structural transformations. Investigations were conducted on nickel alloy IN 738 used as a structural material for the manufacture of gas turbine blades. The chemical composition of the alloy is given in Table 1.