| Engine is the core component of the aircraft, ships, rockets and other equipment, provide power for the device, its reliability related to the safety of national defense and life of personnel. And the reliability of the superalloys be used in engine contain weight 60%-70% is more important in the engine.The application rate of the foreign countries on the returns material of superalloy is relatively higher than our country utilization rate.For this reason, how to make the superalloy returns material to be used is the biggest challenge. In this paper, the K417 G alloy was studied in the comprehensive and systematic for the returns of 50%, 70%, 100% of the alloy and the 100% returns of the alloy was carried out for 4 times. The chemical composition, gas content and microstructure of the alloy were measured. The tensile properties, high temperature creep properties and fatigue properties of the alloy were determined. The results show that the chemical composition, impurity content and mechanical properties of the returned K417 G alloy meet the technical requirements. When the content of returns materials was increased, the content of O increased obviously, while the content of N increased little. but the content of Mo decreased, the content of Ti, Al, Co and Cr in the main elements changed little. With the number of the return times of 100% returns alloy, the content of Mo in the alloy was slightly decreased, the main elements of Co, Al, Cr, Ti content changed little, and the O content increase, the content of N decreased, and the contents of Si, S and Mn had little change. Returns alloy when melting material unworthy into B and Zr can meet the requirements;The morphology of returns alloy in the eutectic microstructure, grain boundary coursing ?? phase is basically same; with the return material proportion increased, the carbides of strip morphology is gradually reduced, massive and granular carbides increase, fine granular carbides have increasing trend, reduce the amount of carbide. The number of carbides in the return of the alloy decreases with the increase of the number of return times. The tensile strength, section shrinkage rate of elongation of returns alloy all meet the standard requirements, the returns alloy which contain new material, the mechanical properties of the alloy same to and new material, and the tensile strength and cross section shrinkage rate of the 100% returns alloy for return one to four times slightly lower than the new material. The creep initial elongation and strain rate during the steady state of creep for returns alloys are equal. The creep properties of the returns alloy and the creep properties of the new alloy are almost equal. Whether it is new or returns alloys, the thermal fatigue crack easy to propagation along the edge of borides and carbides. The crack growth rate of the returns alloy is significantly faster than the new alloy with the increase of the number of return times. The rotary bending fatigue test at 900℃ showed that the fatigue life of the returned alloy was lower than that of the new alloy. With the increase of the number of return times, the fatigue life of the returned alloy lower, but the test show that the fatigue life of four times returns alloy still exceed standard request. Subject test data show that the property of the proportion of 100% of returns alloy and the 100% returns alloy which remelt no more than four times alloys meet the standard requirements.Also It can be applied to engineering... |
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