三联冶炼+挤压制备的GH4710合金棒材热变形行为及热加工图

Hot deformation behavior and hot processing maps of triple-smelted GH4710 alloy after extrusion

摘要:

采用真空感应（VIM）+电渣重熔（ESR ）+真空自耗（VAR）三联冶炼制备的GH4710合金铸锭经挤压获得棒材。在Gleeble1500试验机上开展等温压缩实验，研究了三联铸锭挤压态GH4710合金在温度1050~1150 ℃，应变速率0.01~5 s-1条件下的热变形行为。结果表明，应力应变曲线具有明显的动态再结晶特征，且应力随着变形温度的升高和应变速率的降低而明显减小。基于应力应变曲线，建立了合金动态再结晶临界应变模型，同时建立了考虑应变影响的Arrhenius本构模型来精确描述合金应力、应变速率和温度的依赖关系。最后以动态材料模型为基础构建了合金热加工图，结合显微组织分析，明确了合金流变失稳特征为不均匀显微组织，确定了合金最佳锻造工艺参数范围为1050 ℃≤T≤1100 ℃、0.01 s-1≤ ≤0.1 s-1。

关键词:GH4710合金;挤压;三联冶炼工艺;热加工图

Abstract:

The hot deformation behavior of as-extruded GH4710 alloy prepared by vacuum induction melting(VIM)+electroslag remelting(ESR)+vacuum arc remelting(VAR) triple smelt process was studied by hot compression tests at temperatures of 1050~1150℃ and strain rates of 0.01~5 s-1. The results show that the stress-strain curves have obvious dynamic recrystallization characteristics, and the stress decreases significantly with increasing temperature and decreasing strain rate. Base on the compressive true stress vs. true strain curves, the critical strain model of dynamic recrystallization was developed. At the same time, the Arrhenius constitutive model considering the influence of strain is established to accurately describe the dependence of alloy stress, strain rate and temperature. Finally, based on the dynamic material model, the thermal processing diagram of the alloy was constructed, and combined with the microstructure analysis, the rheological instability of the alloy was clarified as the uneven microstructure , and the hot working parameters of the as-extruded-trip-smelted GH4710 alloy are suggested to be the deformation temperatures of about 1050~1100 ℃ and the strain rate of about 0.01~0.1 s-1.

Key words:GH4710 alloy; extrusion; triple smelt process; hot processing map