铸造K4169合金晶粒细化的研究

A study of grain refinement with addition of refiner in superalloy K4169

选用Ｋ４１６９铁－镍基高温合金研究了向熔体中加入ＮｉｘＡｌｙＴｉｚ金属间化合物对合金冷凝后的晶粒尺寸、枝晶组织等凝固组织特征的影响。结果发现，加入微量ＮｉｘＡｌｙＴｉｚ细化剂并控制合金液的均匀化处理过程可显著细化晶粒，将Ｋ４１６９铸件整体晶粒细化至０．１～０．２ｍｍ，达到ＡＳＴＭ１～３级，同时，枝晶组织和ＭＣ型碳化物也有明显变化。而且，本研究选用的ＮｉｘＡｌｙＴｉｚ细化剂由于其成分特点对合金的结晶特性及凝固组织无不良影响。因此可认为，加入微量的ＮｉｘＡｌｙＴｉｚ细化剂是获得Ｋ４１６９高温合金细晶铸件的有效方法。

Grain size and dendrite morphologies of Fe Ni based superalloy K4169 are investigated with the melt addition of Ni xAl yTi z refiner.It is found that the grain size of K4169 cast bar can be refined obviously to 0.1～0.2mm,close to the order of ASTM 1～3,due to adding refiner and lowering the melt homogeneous temperature during the melting and casting process.In addition,the microstructure and MC carbide morphology vary obviously.With refinement of grains,the additive Ni xAl yTi z has the advantage of little influence on the freezing characters,alloy composition as well as on phase constitutions because of its composition feature.It is considered therefore that the addition of Ni xAl yTi z refiner is one of effective and practical method to obtain fine grained castings of K4169 superalloy.