摘要
围绕车用涡轮增压器关键部件——钛铝合金涡轮,探讨其在超速试验飞散失效后的微观组织因素和力学特性。选用Ti-47.5Al-2.5V-1.0Cr(at%)钛铝合金,通过离心铸造工艺制备涡轮样品,并在特定转速条件下进行超速试验,从涡轮心部取样进行拉伸性能测试和显微组织观察。结果表明,涡轮在超速试验中提前发生飞散失效,心部径向抗拉强度的平均值为392 MPa,仅达材料本征强度的73%,这是失效的主要宏观原因。裂纹起源处层片组织与轮背面夹角在30°~60°,导致材料局部强度降低。结合Griffith断裂理论和PST晶体理论,当外载荷与层片取向夹角处于30°~60°时,TiAl合金材料的PST晶体表现出最低强度,导致涡轮的超速飞散失效。
Focusing on the key component of automotive turbochargers—TiAl alloy turbine,the microstructural factors and mechanical characteristics of the turbine failed during its overspeed test were explored.The experiment employed Ti-47.5Al-2.5V-1.0Cr(at%)titanium-aluminum alloy,and turbine samples were prepared using a centrifugal casting process.Overspeed tests were conducted under specific rotational speed conditions,and the tensile property testing and microstructure observation were carried out for the samples taken from the turbine core.The results indicate that the turbine undergoes premature fragmentation failure during the overspeed test,with an average radial tensile strength of 392 MPa at the core,which is only 73%of the material's intrinsic strength,serving as the primary macro-cause for failure.The angle between the lamellar structure at the crack initiation site and the back surface of the wheel is between 30°-60°,leading to a reduction in local material strength.Based on Griffith's fracture theory and PST crystal theory,when the angle between the external load and the lamellar orientation is 30°-60°,the PST crystals of TiAl alloy exhibit the lowest strength,ultimately resulting in the turbine's overspeed fragmentation failure.
作者
杨虎
李宝华
YANG Hu;LI Baohua(Institute of Materials Research,Tsinghua Shenzhen International Graduate School,Shenzhen 518063,China;Shenzhen Pacific Union Precision Manufacturing Co.,Ltd.,Shenzhen 518110,China)
出处
《热加工工艺》
北大核心
2025年第23期208-212,共5页
Hot Working Technology
关键词
钛铝合金
涡轮
失效
抗拉强度
超速飞散断口
层片组织
TiAl alloy
turbine
failure
tensile strength
overspeed fragmentation fracture
lamellar microstructure
