一次γ′相对GH4151合金高温变形特性及动态再结晶行为的影响

Effect of primaryγ′phase on deformation characteristics and dynamic recrystallization behavior of GH4151 alloy

以锻态GH4151合金作为研究对象,分析了不同热处理温度及保温时间对一次γ′相析出回溶规律的影响,确定进一步循环热处理的参数;进而,通过循环热处理改变一次γ′相的形态及分布,并对经循环热处理后的试样进行热压缩试验,采用电子背散射衍射(EBSD)、扫描电镜(SEM)和透射电镜(TEM)等分析一次γ′相对GH4151合金的高温变形特性及动态再结晶行为的影响。结果表明:1130℃保温15 min,GH4151合金的γ′相回溶现象比较明显,晶界处的一次γ′相分布较均匀,因此选定1130℃保温15 min作为进一步循环热处理的基本参数;随着循环热处理次数的增加,钉扎于晶界处的一次γ′相更加细小弥散圆润,在高应变速率下,合金流变应力提升显著;晶界一次γ′相的存在,使得GH4151合金在热变形过程中动态再结晶机制主要为γ′相诱导动态再结晶及连续动态再结晶。

Taking the forged GH4151 alloy as the research object,the influence of different heat treatment temperatures and holding time on the precipitation and dissolution law of primaryγ′phase was analyzed,and the parameters for further cyclic heat treatment were determined.Furthermore,the morphology and distribution ofγ′phase were changed through cyclic heat treatment,and hot compression tests were conducted on the samples after cyclic heat treatment.The effects of primaryγ′phase on the high temperature deformation characteristics and dynamic recrystallization behavior of the GH4151 alloy were analyzed by means of electron backscatter diffraction(EBSD)technique,scanning electron microscopy(SEM)and transmission electron microscopy(TEM).The results show that theγ′phase re dissolution phenomenon of the GH4151 alloy is more obvious when held at 1130℃for 15 min,and the distribution of primaryγ′phase at grain boundaries is more uniform.Therefore,holding at 1130℃for 15 min is selected as the basic parameter for further cyclic heat treatment.As the number of cyclic heat treatment increases,the primaryγ′phase pinned at the grain boundaries becomes finer and more dispersed and rounded.Under high strain rates,the flow stress of the alloy increases significantly.The presence of primaryγ′phase at grain boundaries results in the dynamic recrystallization mechanism of the GH4151 alloy during hot deformation mainly beingγ′phase induced dynamic recrystallization and continuous dynamic recrystallization.