Gaiduk S. Investigation of tantalum influence on structure and properties of alloy ЗМИ-3У.

Object of research - Spesimens of alloy ЗМИ-3У with directed (mono) and equiaxed macrostructure alloyed by tantalum within the range of investigation. Goal of research - Optimization of the limits of alloying by tattalum for alloy ЗМИ-3У in order to improve the set of its service properties and producibility while manufacturing the blades using the directional (mono) and equiaxial crystallization methods. Methods of research: Thermal - differential and metallographic analyses, standard mechanical and corrosion tests, X-ray microspectral and X-ray structural analyses. Theoretical and practical results: There has been investigated the influence of tantalum on structural, high-temperature, corrosion-resistant and manufacturing properties. Novelty: It has been found out, that while tantalum content is increased up to 5 mas. % in alloy ЗМИ-3У the initial and final temperatures of gamma-prime phase solution and euthectic transformation rise by 110, 75 and 50 C correspondently. Besides, liquidus temperaturefalls by 30 C. It has been found out, that for alloy ЗМИ-3У the best high-temperature strength values are achieved within the test temperature range from 800 to 1000 C at 4 mas. % tantalum. It has been determined, that for alloy ЗМИ-3У the best high-temperature corrosion resistance at test temperature of 850 C is achieved at 3 mas. % tantalum. The alloying limits for alloy ЗМИ-3У have been optimized taking into consideration the priority of the best high-temperature strength values, producibility and technical requirements to alloying limits for alloys produced by directional (mono) crystallization and account for (4,0±0,3%) tantalum, i.e. (3,7-4,3%) tantalum by mass. Manufacturing procedure of the blades made of alloy ЗМИ-3УM by directional (mono) crystallization method for ground energetic turbine MS-5001 has been tried out under the industrial conditions of JSC "Motor-Sich". Manufacturing procedure of the blades made of alloy ЗМИ-3УM by directional (mono) crystallization method for ground unit Д-336 has been tried out under the industrial conditions of ZMKB "Progress". Application: Improvement of the service properties of the developed alloy ЗМИ-3УМ has allowed to introduce it as the material for blades with increased service-life for gas-transporting unit ГТК-10И instead of alloy ЗМИ-3У. Economic benefit of the developed alloy ЗМИ-3УМ introduced instead of alloy ЗМИ-3У accounts for 980 thousand grn. per year at "CherkassyTransGas".