复合包套轧制工艺对难变形高温合金GH720Li组织的影响

Effect of compound jacketing rolling process on microstructure of difficult-to-deform superalloy GH720Li

研究了复合包套轧制工艺对难变形高温合金GH720Li组织的影响.结果表明:采用复合包套变形可以有效控制合金的轧制温度,减少轧辊与钢锭的摩擦力,改善难变形合金的表面质量及变形组织均匀性,防止轧制过程开裂.随着轧制变形量的增大,铸态GH720Li合金粗大的柱状树枝晶组织充分破碎,热变形后合金轧态晶粒度为ASTM5级,一次γ′相尺寸约为0.46μm,同时消除了低倍粗晶现象.经过热处理后GH720Li合金晶粒度为ASTM4级,改善了强化相γ′相的大小、数量及其分布状态,获得了良好的力学性能.

The effect of compound jacketing rolling process on microstructure of GH720Li was studied.The result shows that rolling temperature can be controlled effectively by compound jacketing deformation,frictional force between roller and ingot can be reduced,surface quality and deformation microstructure uniformity of difficult-to-deform superalloy GH720Li can be improved,and cracks can be prevented in the rolling process.With the increase of draft,the coarse columnar dendritic microstructure of as-cast GH720Li is completely broken.Grain size is ASTM5 after hot deformation,the size of primary gamma-prime phase is about 0.46 μm and macroscopic coarse grain phenomenon can be eliminated.Grain size is ASTM4 after heat treatment.Size,quatity and distribution state of strengthening γ′phase are improved.Therefore,excellent mechanical properties are obtained.