Haynes 230合金热变形组织演化规律研究

Microstructure Evolution of Haynes230 Superalloy during Hot Deformation

摘要:

采用Thermecmastor-Z型热模拟机对Haynes230合金进行变形温度为950~1250 ℃，应变速率为0.001～10 s-1范围内的高温压缩试验，并利用OM和TEM分析研究了热变形组织演化特征和动态再结晶形核机制。结果表明：动态再结晶晶粒尺寸和体积分数随着变形温度的升高而增大和增多，随着应变速率的升高而变小和减少；晶界弓出是合金动态再结晶的主要形核机制，项链组织在热变形组织演化过程中起着重要作用；动态再结晶稳态晶粒尺寸Dss与Z参数之间符合幂函数关系

Abstract:

Hot compression tests of Haynes230 superalloy were conducted using a Thermecmastor-Z simulator in the temperature range of 950~1250 oC and strain rates of 0.001~10 s-1. Optical microscope (OM) and transmission electron microscope (TEM) techniques were employed to investigate the microstructure evolution and nucleation mechanisms of dynamic recrystallization (DRX). Results show that both the size and volume fraction of DRX grains increase with the increasing of deformation temperature but decrease with the increasing of strain rate. The dominant nucleation mechanism of DRX is bulging of the original grain boundaries. The necklace structure of recrystallized grains along original grain boundaries plays an important role for nucleation and growth of DRX grains. The relationship between DRX steady state grain size and Zener-Holloman parameter can be well established by a power law function