挤压工艺参数对FGH96合金棒材显微组织的影响

Influence of extrusion process parameters on microstructure of FGH96 alloy bar

对FGH96合金进行了不同挤压工艺参数的热挤压变形,研究了挤压温度、挤压比、挤压速度对FGH96合金热挤压棒材的晶粒组织和γ′相的影响,以及γ′相对再结晶晶粒长大的影响。结果表明:在实验选定的挤压工艺参数范围内,FGH96合金均发生了动态再结晶,随着挤压温度的升高,再结晶晶粒尺寸增大;在FGH96合金棒材的显微组织中,大尺寸γ′相呈链状分布于晶界,小尺寸的γ′相弥散分布在晶粒内部;随着挤压温度的升高,晶界处的大尺寸γ′相逐渐溶解,晶界迁移、阻力减小,再结晶晶粒长大,挤压温度为1100℃时,晶界处的大尺寸γ′相开始快速溶解,再结晶晶粒开始明显长大;挤压比和挤压速度的影响主要体现在单位时间内等效应变量和变形潜热对再结晶形核和长大的双重作用上,挤压比或者挤压速度过大或过小均会出现不均匀组织。

The hot extrusion deformation of FGH96 alloy was carried out under different extrusion process parameters,and the influences of extrusion temperature,extrusion ratio and extrusion speed on the grain structure,γ′phase of hot-extruded FGH96 alloy bar and the influences ofγ′phase on recrystallization grain growth were studied.The results indicate that the dynamic recrystallization in the FGH96 alloy happens within the range of extrusion process parameters selected by the test,and the recrystallized grain size increases with the increasing of extrusion temperature.In the microstructure of FGH96 alloy bar,the large-sizeγ′phase is distributed along the grain boundary in a chain shape,and small-sizeγ′phase is dispersed and distributed inside the grain.With the increasing of the extrusion temperature,the large-sizedγ′phase at the grain boundary gradually dissolves,the grain boundary remove,the migration resistance decreases,and the recrystallized grains grow up.At the extrusion temperature of 1100℃,the large-sizedγ′phase at the grain boundary begins to dissolve rapidly,and the recrystallized grains begin to grow obviously.The influences of extrusion ratio and extrusion speed are mainly reflected in the dual effects of effective strain and deformation latent heat on the nucleation and growth of recrystallization within unit time,and excessively large or small extrusion ratio or extrusion speed cause uneven structure.