(1. 中南大学航空航天学院，长沙 410083；
2. 中南大学粉末冶金国家重点实验室，长沙 410083；
3. 中南林业科技大学机电工程学院，长沙 410004)
摘 要: 采用Gleeble3180D型热模拟试验机对热挤压态FGH96合金在变形温度1020~1140 ℃，应变速率0.001~1.0 s-1进行热压缩实验，分析真应力-真应变曲线，绘制热加工图。并针对热挤压态粉末冶金高温合金FGH96在热压缩温度低于1080 ℃时的开裂现象，利用热模拟压缩实验方法，确定在变形温度为1050 ℃、应变速率为0.001~1.0 s-1的热压缩变形过程中的开裂临界应变量，观察变形后试样的裂纹形貌和显微组织，并利用有限元分析方法对热压缩变形过程进行模拟。结果表明：试样中部位置受拉应力作用沿着变形方向产生鼓形变形，当达到临界应变量后，产生呈沿晶断裂的宏观裂纹，并且随着应变速率的减小，裂纹产生的临界应变量逐渐减小；在低应变速率条件下，在宏观裂纹产生之前，试样内部晶粒之间出现了微观开裂的现象，并造成应力下降。
关键字: 粉末冶金高温合金；FGH96合金；热加工图；热挤压工艺；热压缩实验；鼓形变形；宏观裂纹
（1. School of Aeronautics and Astronautics, Central South University, Changsha 410083, China;
2. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China;
3. College of Mechanical and Electrical Engineering, Central South University of Forestry and Technology, Changsha 410004, China）
Abstract:The hot compression tests were carried out for hot extruded FGH96 alloy in the temperature range of 1020-1140℃and strain rate range of 0.001-1.0 s-1 by using Gleeble 3180D thermal simulation system. The true stress-true strain curves were analyzed, and the processing maps were developed. And for the phenomenon that the hot extruded powder metallurgy superalloy FGH96 cracked severely at the hot compression temperatures below 1080 ℃, the critical strains of cracking were determined during hot compression at deformation temperature of 1050 ℃ and strain rates of 0.001-1.0 s-1. The fractures and microstructures of deformed specimens were observed, and the hot compression was simulated by using finite elemental method. The results show that the specimens occur barrel deformation that is affected by tensile stresses in the middle of specimens, beyond the critical strains of cracking, fractures form with intergranular cracks, and the critical strains increase with increasing the strain rate. At low strain rate, the micro-cracks form between inner grains before formation of macro-fractures, and the flow stress decreases.
Key words: powder metallurgy superalloy; FGH96 alloy; processing map; hot extrusion; hot compression; barrel deformation; macro-fracture
