Material properties and manufacture technologies analysis of combined ship power-plants from different steels

The peculiarities of the structure of welded joints of different steels caused by their pronounced chemical, structural and mechanical heterogeneity must be taken into account when designing materials of a structure and choosing the technology of its manufacture. In the manufacture of composite structures of different steels, most existing welding methods can be used. The search for the most rational method of manufacturing ship auxiliary mechanisms of different steels, as well as for welding units of the same alloy, is determined by the conditions for obtaining a welded structure of high quality. It is not necessary to take into account the cost minimization and optimization of the type of connection, the grade of the alloying elements as well as the total cost of the construction. When welding steels of the same structural class, any additional requirements for the choice of a welding method and its mode, with consideration for the heterogeneity of the joint, can usually be ignored. Within one and the same structural class, the thermophysical properties of steels do not significantly differ. The properties of the transition layers of the seam due to the penetration of the base metal in such compounds in most cases are not significantly different from the properties of the weld metal either. The consideration of the choice of welding materials and the base metal for the compounds to be tested is the most difficult due to the significant difference between the welding steels. Therefore, the question of preserving properties in the transition areas of the seam, as well as the minimizing the diffusion layers in the alloy zone, are of particular importance for such compounds. It is important to compare the properties of welded joints using thermally-hardened and dispersion-hardened austenitic steels. For the steels of this class, heat treatment after welding is required to restore the properties of the surrounding area. The choice of the welded joint heat treatment mode is of particular value, it depends on the level of alloying both steel and the welded joint. The magnitudes of operational loads on the ship’s power plants are also taken into account