中國有色金屬學報(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 28 No. 12 December 2018 |
（1. High Temperature Material Research Division, Central Iron & Steel Research Institute, Beijing 100081, China;
2. School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, China;
3. Department of Strategic Development, China Iron & Steel Research Institute Group, Beijing 100081, China）
Abstract:The independent influence of microstructural features on fracture toughness of TC21 alloy with lamellar microstructure was investigated. Triple heat treatments were designed to obtain lamellar microstructures with different parameters, which were characterized by OM and SEM. The size and content of α plates were mainly determined by cooling rate from single β phase field and solution temperature in two-phase field; while the precipitation behavior of secondary α platelets was dominantly controlled by aging temperature in two-phase field. The content and thickness of α plates and the thickness of secondary α platelets were important microstructural features influencing the fracture toughness. Both increasing the content of α plates and thickening α plates (or secondary α platelets) could enhance the fracture toughness of TC21 alloy. Based on energy consumption by the plastic zone of crack tip in α plates, a toughening mechanism for titanium alloys was proposed.
Key words: titanium alloy; lamellar microstructure; fracture toughness; crack tip plastic zone; toughening mechanism
