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以服役900 h的DZ125合金叶片为研究对象,通过对叶片服役前后的枝晶干、枝晶间、晶界及碳化物各类组织退化行为的研究,确定了枝晶干g’相的体积分数作为反映服役温度的可量化表征参量.结合叶片用DZ125合金在900~1100℃下显微组织的演变行为,研究了热暴露温度与枝晶干g’相体积分数之间的量化对应关系.在此基础上,提出了一种基于显微组织的涡轮叶片服役温度的实验评估方法.同时,分别假设叶片服役温度恒定以及考虑叶片实际服役温度变化2种情况,实现了对等效平均服役温度(T_(ave))及等效最高服役温度(T_(max))的定量评估.评估结果表明:叶片叶身中部服役温度最高,由叶身中部向叶尖和叶根服役温度逐渐降低;同一截面服役温度由高到低依次为:进气边>叶盆>排气边>叶背;服役温度最高的区域为叶身中部截面的进气边,服役时经历的等效最高服役温度为1050~1100℃.叶片等效平均服役温度及等效最高服役温度的分布规律一致,但部分部位的等效最高服役温度高于等效平均服役温度,本研究认为叶片的等效最高服役温度的评估结果更为合理.
The 900-day DZ125 alloy blade was used as the research object. The degradation of dendrite dry g’-phase was studied by studying the degradation behavior of dendrites, dendrites, grain boundaries and carbide before and after service. As a quantitative characterization parameter reflecting the service temperature.Combined with the evolution of the microstructure of the blade DZ125 alloy at 900-1100 ℃, the quantitative relationship between the thermal exposure temperature and the dendrite dry g ’phase volume fraction was studied. Based on this, an experimental method for evaluating the service temperature of turbine blades based on microstructure was proposed.At the same time, assuming that the service temperature of blade was constant and the actual service temperature of blade was taken into account, T_ (ave)) and the equivalent maximum service temperature (T_ (max)). The evaluation results show that the service temperature in the middle part of the blade leaves is the highest, The service temperatures from high to low are as follows: intake side> pot> exhaust side> leaf back; the highest service temperature is the intake side of the middle section of the blade body, and the equivalent service temperature under service is 1050 ~ 1100 ° C. The equivalent average service temperature and the equivalent maximum service temperature have the same distribution, but the equivalent service temperature of some parts is higher than the equivalent service temperature. In this study, the evaluation results of the equivalent maximum service temperature of blades are more reasonable .