Obtaining of bimetallic pipe billets with internal layer of heat-resistant nickel-cobalt alloy EK102 by explosive welding

摘要

The features of preparation the compound by explosive welding in two-layer tubular billet with the combination of layers steel OHN3M and refractory nickel-cobalt alloy EK102. Due to the fact that the EK102 has refractory metals such as tungsten, cobalt, chromium connection this alloy with other materials by all kinds of welding is difficult. One of the factors that make it difficult to obtain high-quality bimetallic products of these components by explosive welding is the presence of refractory film on the surface of the heat resistant alloy, which hinders the process of self-purification and activation of surfaces in the explosive welding. The scheme of coating alloy EK102 inside of the cylindrical surface of steel OHN3M is developed. Explosive welding was carried out by the scheme with a synchronous initiation of opposite charges. This scheme was chosen as an alternative to welding of cylindrical items in a matrix. Bimetallic pipes without damage to the inner and outer layer were obtained at result of experiments. Ultrasonic testing showed 100% confluent layers adhesion. Further studies carried out at circular specimens cut from the pipe. The microstructure of transition zone is investigated. Radial compression tests of circular samples are carried out. During the inspection of the connection zone of the bimetal bundles are not detected. Thus, modes of explosive welding allowed to create necessary conditions for cleaning the surface of a refractory alloy of oxide films during the welding process and provided high bonding strength of the layers without the continuous layers of cast melt.