(1. 中南大學航空航天學院，長沙 410083；
2. 中南大學粉末冶金國家重點實驗室，長沙 410083；
3. 中南林業(yè)科技大學機電工程學院，長沙 410004)
摘 要: 采用Gleeble3180D型熱模擬試驗機對熱擠壓態(tài)FGH96合金在變形溫度1020~1140 ℃，應變速率0.001~1.0 s-1進行熱壓縮實驗，分析真應力-真應變曲線，繪制熱加工圖。并針對熱擠壓態(tài)粉末冶金高溫合金FGH96在熱壓縮溫度低于1080 ℃時的開裂現(xiàn)象，利用熱模擬壓縮實驗方法，確定在變形溫度為1050 ℃、應變速率為0.001~1.0 s-1的熱壓縮變形過程中的開裂臨界應變量，觀察變形后試樣的裂紋形貌和顯微組織，并利用有限元分析方法對熱壓縮變形過程進行模擬。結(jié)果表明：試樣中部位置受拉應力作用沿著變形方向產(chǎn)生鼓形變形，當達到臨界應變量后，產(chǎn)生呈沿晶斷裂的宏觀裂紋，并且隨著應變速率的減小，裂紋產(chǎn)生的臨界應變量逐漸減小；在低應變速率條件下，在宏觀裂紋產(chǎn)生之前，試樣內(nèi)部晶粒之間出現(xiàn)了微觀開裂的現(xiàn)象，并造成應力下降。
關鍵字: 粉末冶金高溫合金；FGH96合金；熱加工圖；熱擠壓工藝；熱壓縮實驗；鼓形變形；宏觀裂紋
（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
