变形参数对FGH4113A粉末高温合金微观组织演化的影响

Effect of Deformation Parameters on Microstructure Evolution of FGH4113A Powder Metallurgy Superalloy

摘要:

本文针对一种新型粉末高温合金FGH4113A（WZ-A3）进行了一系列热压缩实验，探究了变形温度、应变速率、应变量对微观组织演化的影响规律，并提出了获得细小均匀“γ+γ′双相晶粒组织”的热变形参数。结果表明：在温度1100 ℃、应变速率0.1 s-1、真应变0.1~0.7范围内，应变增大有利于促进动态再结晶以及细化晶粒。随应变增加，γ"相体积分数先减小后增大，随后保持稳定，并且在热变形过程中γ"相形貌逐渐趋于球形。在温度1100 ℃、变形量50%、应变速率0.01~1 s-1范围内，应变速率增大能够提高动态再结晶程度并细化晶粒。应变速率由0.01~0.1 s-1增大至1 s-1时，由于绝热温升以及位错滑移加剧，γ"相体积分数减小约2%。在应变速率0.1 s-1、变形量50%、温度1070~1160 ℃范围内，变形温度的提升有利于促进动态再结晶和晶粒长大。随着变形温度升高至1130 ℃，γ"相已大量溶解，钉扎晶界能力大幅减弱，平均晶粒尺寸增大至12.1 μm。在变形温度1100 ℃、应变速率1 s-1、50%变形量条件下可以获得均匀细小的“γ+γ′双相晶粒组织”，晶粒度能够达到12级以上。

Abstract:

Through a series of hot compression tests on a novel powder metallurgy superalloy FGH4113A (WZ-A3), the effects of deformation temperature, strain rate and strain on the microstructure evolution were investigated. The results demonstrate that when the temperature is 1100 ℃, the strain rate is 0.1 s-1 and the true strain is 0.1~0.7, the increase of strain is beneficial to promote dynamic recrystallization and grain refinement. With the increase of strain, the volume fraction of γ" phase first decreases, then increases, and eventually remains stable. The morphology of γ" phase gradually becomes spherical during the thermal deformation process. Under the conditions of temperature 1100 ℃, deformation 50% and strain rate of 0.01~1 s-1, the increase of strain rate can improve the degree of dynamic recrystallization and refine the grains. With the increase of strain rate from 0.01~0.1 s-1 to 1 s-1, adiabatic temperature rise and dislocation slip intensify, resulting in the volume fraction of γ" phase reduces by about 2%. When the strain rate is 0.1 s-1 and the deformation is 50%, the increase of deformation temperature can promote dynamic recrystallization and grain growth in the temperature range of 1070~1160 ℃. With the deformation temperature rising to 1130 ℃, a large quantity of γ" phase has dissolved, the ability to pin the grain boundary has been significantly weakened, and the average grain size has increased to 12.1 μm. At the deformation temperature of 1100 ℃, strain rate of 1 s-1 and deformation of 50%, fine and uniform “γ+γ′ dual-phase structure " and the grain size above ASTM 12 can be obtained.