吹砂对DD6单晶高温合金表面完整性和高周疲劳强度的影响  

Effects of Sand Blasting on Surface Integrity and High Cycle Fatigue Properties of DD6 Single Crystal Superalloy

作　　者：李嘉荣[1] 董建民[1] 韩梅[1] 刘世忠[1] LI Jiarong;DONG Jianmin;HAN Mei;LIU Shizhong(Science and Technology on Advanced High Temperature Structural Materials Laboratory,Beijing Institute of Aeronautical Materials,Beijing 100095,China)

机构地区：[1]北京航空材料研究院先进高温结构材料重点实验室,北京100095

出　　处：《金属学报》2023年第9期1201-1208,共8页Acta Metallurgica Sinica

摘　　要：将标准热处理的试样分别采用粒径为150、124和100μm白刚玉砂在0.5 MPa压力下吹砂,研究吹砂对第二代单晶高温合金DD6表面完整性的影响;对未吹砂和粒径150μm吹砂试样分别进行760和980℃旋转弯曲高周疲劳性能测试,研究吹砂对DD6合金疲劳性能的影响。结果表明:吹砂会破坏单晶高温合金的表面完整性,使表面出现砂粒切削造成的不规则凹坑,改变表面形貌;砂粒粒径增加,表面粗糙度和显微硬度均增大;吹砂使大量位错在γ相通道中滑移,靠近表面区域位错密度较大;并且,大量位错剪切γ’相,形成反相畴界和层错;吹砂造成形变强化、引入残余应力;150μm、0.5 MPa吹砂对DD6合金760℃旋转弯曲疲劳性能基本无影响,但会降低合金980℃疲劳性能,对低应力幅区疲劳寿命影响较大,使疲劳强度下降约7.3%。缺口效应、氧化损伤、形变强化和残余压应力的耦合作用导致吹砂与不吹砂试样疲劳寿命产生差异。DD6 is a second generation single crystal superalloy independently developed in China,which offers advantages such as high-temperature strength,stable structure,and satisfactory casting process performance.Currently,it is being widely used in development of aviation engine turbine blades.Sand blasting can be performed for surface cleaning and adjusting surface roughness of single crystal turbine blades and is an essential process in manufacturing of single crystal blades.Although sand blasting has been widely used in the manufacturing process of DD6 alloy turbine blades,only few reports studied the impact of sand blasting on the surface integrity and fatigue performance of DD6 alloy.Therefore,research is required to provide a theoretical basis for the safe service of DD6 alloy turbine blades.In this work,several specimens after a standard heat treatment are blasted with white corundum sand with 150,124,and 100 μm diameters at 0.5 MPa to study the effect of sand blasting on the surface integrity of DD6alloy;the rotary bending high cycle fatigue properties of the specimens without and with sand blasting(blasting with white corundum sand with 150 μm diameter) were tested at 760 and 980oC,respectively,to study the effect of sand blasting on the alloy's fatigue property.The results show that sand blasting destroys the surface integrity of the single crystal superalloy,resulting in irregular pits on the surface caused by the cutting by sand particles while changing the surface morphology as well;the surface roughness and microhardness increase with sand particle size increase;after sand blasting,many dislocations slip in the γ phase,and the dislocation density near the surface is high.Additionally,many dislocations shear the γ′ phase,forming antiphase domain boundaries and stacking faults;sand blasting results in deformation strengthening and residual stress;blasting with 150 μm diameter sand at 0.5 MPa has a small effect on the rotary bending high cycle fatigue properties of DD6 alloy at 760oC,but it considerab

关 键 词：单晶高温合金 DD6 表面完整性 高周疲劳 吹砂 

分 类 号：TG132.3[一般工业技术—材料科学与工程]