Heat resistant steels and alloys as a special type of construction materials have begun quite intensively used in connection with the development of turbine construction industry.Turbines in a transmitter or a source of energy used in heat power equipment, aviation and marine engines.More recently, a proliferation of gas turbine design for ground rolling stock (trucks, locomotives).
With increasing the inlet gas temperature decreases the specific fuel consumption per unit power.In this regard, in a fairly short period of time there were heat-resistant steel.Today these materials in the constructions of turbines up to 50% of the total weight.
Heat resisting steel is a material that works not only at elevated temperatures.It is applicable in the condition slozhnonapryazhennogo state for a predetermined time period.The main characteristic that determines the performance of this material is heat resistance.
Under this quality do not understand the causes leading to the destruction of a given deformation strain that can withstand a metallic material in a certain structure at a given temperature for a specific time period.When the stipulated time and voltage, the response is called the tensile strength (long-term).If the deformation is determined, the time and voltage, the quality called creep strength.
Heat-resistant steels have, in addition to strength, ductility, which is to continue until the end of the operation.In terms of plasticity margin estimated reliability of the metal.
important characteristic of the material is notch sensitivity.This is determined by the quality of relationships in the form of time elapsed before the destruction of smooth and notched specimens tested at the same temperature stress.Heat-resistant steel are considered to be insensitive to the split at a ratio equal to or greater than one.
Due to the fact that the rise to the operating temperature occurs over time, wherein the operation corresponds to the beginning, usually ambient temperature, much attention is paid to the values of elasticity and strength.It is important that the values held by the material at room temperature were high enough.
Due to the fact that the heat-resistant steel work under slozhnonapryazhennogo condition which is characterized by constant change in the sign and magnitude of loads, without significance and a high resistance to fatigue.
Today, the use of sophisticated technical solutions to create designs makes it necessary to have a metallic material with a high technological characteristics.For example, in the manufacture of blades for gas turbine engines used forging, precision forming, grinding, mechanical processing by finished products and bars, precision casting, polishing.Production of high-temperature combustion chambers of the metal sheets is performed using compact, cold stamping, spot welding and other technologies.The most common technologies are welding electrodes, friction, diffusion welding, soldering products.All these manipulations require high-quality characteristics of the material used.
Heat resistant steels and alloys by nature are able to maintain higher strength values as to the workers and to the process temperature.This, in turn, imposes a specific mark on the whole metal redistribution technology used, with the deformation of the ingot and prior to the final finishing operations, products to the required surface smoothness and desired dimensions.
