小变形高温退火对Hastelloy C-276合金晶界特征分布和晶界平面分布的影响

Effect of Low-Strains High Temperature Annealing on the Grain Boundary Character Distributions and the Grain Boundary Plane Distributions of Hastelloy C-276

Hastelloy C-276合金经1150℃+30 min固溶处理后,进行不同变形量的冷轧高温退火处理。采用电子背散射(EBSD)技术对退火后的晶界特征分布和晶界面分布进行表征。结果表明,在退火过程中,Σ1小角度晶界比例减小,变形存储能释放,晶界发生迁移,促进了晶界相互作用,从而导致Σ9和Σ27晶界比例增加。与此同时,晶粒发生异常长大并促进了特殊晶界的形成,产生的特殊晶界阻断了大角度晶界的连通性。合金经变形高温退火之后,Σ3晶界分布在{111}晶界面扭转晶界,Σ9晶界分布在[110]晶带倾斜晶界。不同变形条件下,Σ3晶界面与Σ9晶界面分布演变规律不同,原因在于变形退火导致Σ3晶界比例的不同和晶界之间的相互作用的结果。

Hastelloy C-276 was solution-treated at 1150 ℃for 30 min;afterwards,the samples were cold rolled with different reductions and annealed at high temperature.The grain boundary character distribution（GBCD） and the grain boundary plane distribution were characterized by electron backscatter diffraction（EBSD） technique.The results show the fraction of Σ1 boundary decreases during the annealing process.Meanwhile,the fraction of Σ9 boundary and Σ27 boundary increases.This is due to that the stored energy is exposed to the migration of grain boundaries,promoting the interaction of grain boundaries.While grains grow up abnormally during heat treatment,a special boundary forms.The special boundaries disrupt the connectivity of high angle boundaries.After the low-strains higher temperature annealing process,Σ3 boundaries with the {111} plane are twist boundaries while Σ9 boundaries with the [110] zone are tilt boundaries.Under different deformation conditions,the distribution of Σ3 grain boundary plane is different from that of Σ9 grain boundary plane,because the proportion of Σ3 grain boundaries is different and the interactions of special boundaries occur.