GH4169高温合金惯性摩擦焊接头晶粒分布特征

GH4169镍基高温合金的显微硬度、组织和性能对热加工工艺很敏感，工艺控制不当，将会产生粗晶、混晶现象，影响持久缺口敏感性、冲击韧性等性能。试验发现在GH4169高温合金惯性摩擦焊管接头中，沿轴向焊合区附近具有超细晶一细晶的晶粒分布特征。根据GH4169合金动态再结晶的特点，结合惯性磨擦焊过程的特有热变形条件，本文对上述现象进行了分析，研究结果表明，GH4169合金惯性摩擦焊接过程中温度、应变、应变速率是造成焊接区细晶和超细晶组织的根本原因。GH4169合金惯性摩擦焊接头焊合区中热变形金属的动态再结晶过程进行的相当剧烈充分，其晶粒组织呈细小均匀的等轴晶特征，尽管存在着晶粒组织的不均匀性，但未发现粗晶和混晶现象。

Grain Distribution Properties of Superalloy GH4169 Inertia Friction Welded Joint

The Vickers hardness,microstructures and properties of GH4169 are very sensitive to heat processing techniques.Coarsening and mixed grains will appear when mistechniques are choosen.It increases the stress rupture sensitivity and decreases the impact toughness.It was found that superalloy GH4169 inertia friction pipe joint has superfine grain and fine grain distributing along the axial direction by the research experiment conditions.This phenomenon was analyzed according to the dynamic recrystallization property of superalloy GH4169 and the unique thermo deformation condition in inertia friction process.The result shows that the temperature,strain and strain rates of superalloy GH4169 are the main reasons to cause the fine and superfine grain microstructure.Hot deformation dynamic recrystallization process is very rough and sufficient in the weld region of GH4169 inertia friction pipe joint,and the microstructure shows fine and homogenous equiaxed grains.There is no coarsening and mixed grains been found,although the grains are not homogenous in the whole joint.