钛合金熔模精密铸件表面微裂纹形成过程研究  

Formation of Micro Cracks in Investment Castings of Titanium Alloy

作　　者：赵鹏 吴国清[3] 南海 黄东 赵嘉琪 ZHAO Peng;WU Guo-qing;NAN Hai;HUANG Dong;ZHAO Jia-qi(AECC Beijing Institute of Aeronautical Materials, Beijing 100095, China;Beihang University, Beijing 100191, China;Beijing Engineering Research Center of Advanced Titanium Alloy Precision Forming Technology, Beijing 100095, China)

机构地区：[1]中国航发北京航空材料研究院,北京100095 [2]北京市先进钛合金精密成型工程技术研究中心,北京100095 [3]北京航空航天大学,北京100191

出　　处：《精密成形工程》2018年第3期71-76,共6页Journal of Netshape Forming Engineering

基　　金：工信部民机科研项目（MJ-2015-H-G-104）

摘　　要：目的 表征钛合金熔模精密铸件表面组织的特性,研究其如何形成表面微裂纹的过程。方法 通过对钛合金精铸件表面微裂纹形貌进行观察,对表面α层的化学成分、显微硬度进行表征,并通过三点弯曲实验模拟α层在拉应力状态下开裂倾向。结果 微裂纹为冷裂,深度在α层范围内。α层的片层组织较铸件内部组织粗大,O含量和硬度高于铸件内部,在拉应力状态下较铸件内部容易导致裂纹萌生和扩展。结论 钛合金精铸件在凝固过程形成α层,在后续的冷却过程中形成的拉应力或翘曲变形导致相对脆弱的α层形成了表面微裂纹。The paper aims to study features of surface microstructure of titanium alloy investment castings and the for-mation of micro cracks. Morphology on surface micro cracks of titanium alloy investment castings was observed to characterize chemical elements and micro-hardness of α-case. Three-points-bending test was carried out to simulate the cracking tendencies of α-case under pulling. The results show that micro cracks in α-case came into being during cooling of castings. Its depth was within the range of α-case. Lamella organization of α-case was high than that in the inner. The O content and harness were also higher than them in the casting. Cracks were likely to emerge in casting under pressing. The titanium alloy investment casting generates α-case in solidification. Pulling stress and warping in subsequent cooling lead to occurrence of surface micro cracks on α-case which is vulnerable.

关 键 词：钛合金 精密铸造 微裂纹 表面α层 力学性能 

分 类 号：TG292[金属学及工艺—铸造] TG294