火花源原位统计分析技术对涡轮盘的成分分布分析

Element Distribution Analysis of Turbine Disk by Original Position Statistic Distribution Analysis Technique with Spark Source

火花源原子发射光谱原位统计分布分析技术(OPA)是近十几年发展起来的一种大尺度金属截面的高通量成分分布分析技术,具有分析速度快、多元素信号同时定位采集、统计解析信息量大等独特优势,已被广泛应用于中低合金钢铸坯中的成分分布分析。采用火花源OPA技术对铸&锻变形FGH96高温合金航空发动机涡轮盘纵剖面中的主要合金元素Al,Cr,Co,Ti,W,Mo和Nb进行了成分分布分析,并通过适宜的校准曲线的拟合实现了七种合金元素的定量统计解析。采用直读光谱仪对纵剖面轮毂至轮缘的不同部位进行了定点分析,两种方法具有较好的一致性。结果表明,经过新的铸&锻工艺生产的变形FGH96涡轮盘中除了含量较低的Nb元素外,大部分元素的统计偏析度都小于5%。由于涡轮盘不同部位冷却方式的差异,导致轮毂和轮缘上某些元素分布的差异,其中Ti,Nb等碳化物形成元素在轮缘处存在一定的偏析,含量有所升高,而W,Mo和Co则在轮中部分布较不均匀,采用扫描电镜结合能谱分析的方法也观察到了轮缘处了大颗粒的Ti和Nb的碳化物的存在,进一步证实了涡轮盘边缘Ti和Nb偏析的存在。大尺度涡轮盘的元素成分分布分析结果对于FGH96合金涡轮盘新型铸&锻变形工艺的改进和性能提高具有重要的指导作用。

As a high-throughput element distribution analysis technique for metal surface with a large size original position statistic distribution analysis(OPA)combined with spark source atomic emission spectrometry has been developed for more than ten years with the advantage of rapid analysis speed,simultaneous locating acquisition of multi-element signals and large information of statistic analysis.This technique has been widely used in the casting billet segregation analysis for medium and low alloyed steel.In this paper,OPA technique with spark source was used for the distribution analysis of main alloy elements such as Al,Cr,Co,Ti,W,Mo,Nb in FGH96 super-alloy turbine disk prepared by casting&forging deformation.The quantitative statistic analysis of these elements has been obtained by the application of appropriate calibration curves.Fix point analysis in different turbine disk position from wheel hub to flange was done by direct-reading spectrometer and a good agreement of the results of two methods has been obtained.It was found that the statistic segregation degree of the most of the elements in turbine disk is less than 5%except the element of Nb.The distribution in different position of turbine disk was varied with different type of cooling in disk.A certain segregation of carbide forming elements such as Ti and Nb existed in disk flange and the content of elements increased and on the contrary the inhomogeneousdistribution of Co,W,Mo occurred in the middle part of turbine disk.Carbides with a large size were also observed by scanning electron microscope combined with energy spectrum analysis and it can be a further evidence to explain the existence of the segregation of Nb and Ti in disk flange.The element distributionquantitative analysis results will guide the preparation of FGH96 alloy turbine disk by new casting&forging deformation technology and help improve performance.