INFLUENCE OF TEMPERATURE OF THERMAL PROCESSING ON INTERCRYSTALLINE CORROSION RESISTANCE OF WELDED JOINTS

Welded joints with corrosion-resistant steels and heat-resistant alloys requiring different modes of heat treatment to achieve the level of mechanical properties specified in the design documentation are used to manufacture parts and components of the rocket engine turbo-pump unit. For the manufacture of parts and assemblies of liquid-propellant rocket engines at the machine-building enterprises of Ukraine there was a necessity of replacement of half-finished products because of certain difficulties at delivery of materials from EU countries. First of all, it was necessary to replace flat products from high-alloy XH67MBTIO and 06X15H6MB with one alloy that would possess the necessary set of physicomechanical characteristics. In the work, as a replacement for the used heat-resistant alloys, the Inconel 718 alloy welded to 316L steel was chosen. As a result of comparative studies of the intercrystalline corrosion resistance of welded joints of the heat-resistant Inconel 718 alloy with stainless steel, after testing various heat treatment conditions, the low-temperature heating conditions were recommended for soldering at a temperature of 950 degrees C. Samples of welded joints, processed according to the recommended mode, showed increased corrosion resistance.