挤压态镍基粉末高温合金FGH4113A热变形行为及组织演变规律

Hot Deformation Behavior and Microstructure Evolution of a Novel Hot Extruded Nickel-Based Superalloy FGH4113A

摘要:

为探明挤压态新型镍基粉末高温合金FGH4113A热加工性能和调控变形组织，利用Gleeble热模拟试验机、金相显微镜、扫描电子显微镜、背散射电子衍射仪等研究了合金在温度1050~1150 ℃和应变速率0.001~0.1 s^-1范围内热变形行为和显微组织特征。结果表明：挤压态合金热变形前保温，1150 ℃时晶粒尺寸明显粗化。变形温度和应变速率对合金的变形流变应力和再结晶组织明显影响。推荐挤压态合金在γ+γ′双相区热变形，温度和应变速率区间为：1080~1100 ℃和0.001~0.01 s^-1。此区间内变形后，合金再结晶充分，晶粒内残余变形位错密度低，取向差接近，尺寸分布均匀，平均尺寸控制在5 μm以内。可通过局部平均取向差、晶粒扩展取向差和反极图等多个维度分析再结晶晶粒和变形原始晶粒特征。

Abstract:

To investigate hot working properties and to control microstructure of the extruded novel nickel-based superalloy FGH4113A, the thermal deformation behavior and microstructure characteristics were studied using Gleeble thermal compressing machine, OM, SEM, and EBSD. Hot deformation experiments were conducted within the temperature of 1050–1150 ℃ and strain rate of 0.001–0.1 s^–1. The results indicate that the grain size of extruded FGH4113A superalloy increases after holding at 1150 ℃. Deformation temperature and strain rate have a significant impact on the deformation flow stress and microstructure evolution. It is recommended for the extruded superalloy to undergo thermal deformation at temperature of 1080–1100 ℃ and strain rate of 0.001–0.01 s^–1 within the γ+γ′ microduplex region. After deformation under these conditions, grains are fully recrystallized and size distribution is uniform, with average size controlled within 5 μm. The residual dislocation density within the grain is small, and the misorientation differences are not significant. Recrystallized grain and deformed original grain can be distinguished from multiple dimensions such as LAM, GOS, and IPF.