铸态耐热合金CN617热变形行为研究

Hot deformation behavior and processing maps of CN617 nickel-based heat-resistant alloy ingot

用Gleeble-3800热模拟试验机研究了铸态耐热合金CN617退火后在形变温度1050~1180℃,应变速率0.01~10 s-1条件下的热变形行为,建立了该合金的热变形本构方程,绘制了热加工图。结果表明,在形变温度1050~1180℃,应变速率0.01~1 s-1条件下,CN617合金的热变形曲线呈现稳态的流变应力;当在形变温度1100~1180℃,应变速率10 s-1条件下,其热变形行为表现为持续硬化+动态软化过程。CN617合金热变形的热激活能平均为502.35 k J/mol。在形变温度1050~1125℃,应变速率0.2~10 s-1时形成流变失稳。其原因是动态再结晶程度较低,流变应力较高。

Hot deformation characteristics of CN 617 alloy were investigated at 1050-1180 ℃ with strain rate of 0.01-10 s-1 using hot compression tests .The constitutive equation was established and processing maps were developed on the basis of the flow stress curves .The results present that under the condition of deformation temperature range of 1050-1180℃and strain rate range of 0.01-1 s-1 , the flow stress curves show the steady-state flow stress.In the temperature range of 1100-1180 ℃and strain rate of 10 s-1 , the flow stress curves emerge strain hardening plus dynamic strain softening process .The average activation energy for hot working is calculated to be 502.35 kJ/mol.The material undergoes flow instabilities at temperature of 1050-1100 ℃ and at strain rates of 0.2-10 s-1 , as predicted by the incomplete dynamic recrystallization confirmed under optical observation .