梯度加热工艺对自由锻GH4720Li高温合金成形性能的影响  

Formability of Free Forging GH4720Li Superalloy with Different Gradient Heating Process

作　　者：李靖南 董瑞峰[1] 陈子帅 黄东男 曲敬龙 Li Jingnan;Dong Ruifeng;Chen Zishuai;Huang Dongnan;Qujinglong(School of Materials Science and Engineering,Inner Mongolia University of Technology,Hohhot 010051,China;Chinalco Materials Application Research Institute Co.,Ltd.,Beijing 102209,China;Beijing Steel Research Gaona Technology Co.,Ltd.,Beijing 100081,China)

机构地区：[1]内蒙古工业大学材料科学与工程学院,内蒙古呼和浩特010051 [2]中铝材料应用研究院有限公司,北京102209 [3]北京钢研高纳科技股份有限公司,北京100081

出　　处：《稀有金属》2022年第2期162-168,共7页Chinese Journal of Rare Metals

基　　金：内蒙古自治区自然科学基金项目(2018MS05052);内蒙古自治区高等学校科学研究项目(NJZZ18076)资助。

摘　　要：针对GH4720Li高温合金变形过程中存在的内应力大、易开裂等问题,提出了梯度升温工艺。在室式炉加热工艺条件下,利用1 t自由锻锤,对直径50 mm的棒料进行变形量为60%~79%的镦粗实验。研究结果表明:加热工艺不同,对锻件的成材率和晶粒组织均有影响。800~1140℃之间采用随炉升温的方式,使得锻件晶粒尺寸异常长大,且变形量超过68%的锻件发生开裂;而相同条件下,采用梯度升温工艺,锻件温度均匀,内应力小,变形量可达到79%以上未出现开裂现象;锻件边部晶粒未异常长大且分布均匀,平均晶粒尺寸小于10μm。一次γ’相和二次γ’相大量析出,一次γ’相主要分布于晶界处,对晶界起到钉扎作用,二次γ’相主要分布于晶内,且均匀分布。洛氏硬度高达HRC 49以上。梯度升温工艺既改善了GH4720Li高温合金塑性成形性能又细化了晶粒、提高了最终产品的力学性能,同时也极大地提高了生产效率及产品合格率。GH4720 Li alloy is a kind hard of deformation superalloy.It has good oxidation resistance,corrosion resistance,and excellent tensile,endurance,and fatigue properties.At the same time,it has good structure stability after long-term service.Due to the addition of a large number of strengthening elements in the alloy,it is easy to appear such problems as high internal stress and easy cracking during the hot deformation process.With the continuous development of the aviation industry,the performance requirements of high-temperature turbine discs are higher and higher,and the traditional high-temperature alloy materials cannot meet the development needs of the current aviation engine.Advanced aero-engine has always been the most active field of superalloy application,and as the carrier of rotating parts in aero-engine,the excellent performance of the turbine disc has a direct relationship with the thrust of the engine.Due to its high alloying degree,GH4720 Li alloy is one of the most difficult alloys to deform.Its high-temperature strength at 650℃is higher than that of commonly used deformed nickel-based superalloys,which also makes it have great application potential.Given the common problems in the deformation process of the alloy,a gradient heating process was proposed in the pre-forging heating stage.The test was heated in a chamber furnace,and the samples were hot processed on a 1 T free forging hammer.During the hot processing,the bars were hammer forged many times,and the bars were reheated to the initial forging temperature when the temperature was lower than 1000℃.The first forging temperature was 1140℃,and the deformation was in the range of 60%~79%.The microstructure of the forgings was observed by Zeiss AXIO Observer Z1 metallography microscope,the second phase of the forgings was observed by Jeol JCM-6000 scanning electron microscope,and the hardness of the forgings was tested by HR-150 A Rockwell hardness tester.The results showed that the heating process before forging had great influences on the

关 键 词：GH4720Li 梯度加热工艺 微观组织 成形性能 

分 类 号：TG132.32[一般工业技术—材料科学与工程]