Heat Treatment of Metals ›› 2024, Vol. 49 ›› Issue (6): 277-281.DOI: 10.13251/j.issn.0254-6051.2024.06.043

• STANDARDIZATION • Previous Articles     Next Articles

Comparative analysis of domestic and foreign standards for metallographic examination of α+β titanium alloy for surgical implants

Li Fan1,2,3, Gao Na1,2,3, Zhang Luwen1,2,3, Guo Linlin1,2,3, Lou Gui1,2,3, Zhang Bo1,2,3   

  1. 1. Shandong Provincial Key Laboratory of Biological Evaluation of Medical Devices, Jinan Shandong 250101, China;
    2. Key Laboratory for Safety Evaluation of Biomaterials and Medical Devices, NMPA, Jinan Shandong 250101, China;
    3. Shandong Institute of Medical Device and Pharmaceutical Packaging Inspection, Jinan Shandong 250101, China
  • Received:2023-11-12 Revised:2024-03-19 Online:2024-06-25 Published:2024-07-29

Abstract: Microstructure requirements of titanium alloy in surgical implant standards in domestic and foreign were compared and analyzed. The microstructure of plates in GB/T 13810-2017 requires that the original β grain should be fully broken, and continuous grain boundary α phase is not allowed, the microstructure of bars and wires should conform to figure A.1 (a-i) of the standard. The latest versions of ISO 5832-3, ASTM F136, and ASTM F1472 all specify that the microstructure shall be equiaxial and/or elongated primary α phase distributed on the transformed β matrix, with no continuous α network on the prior β grain boundaries. Among them, the transverse microstructure of the bars in ISO 5832-3 shall correspond to A1-A9 in ISO 20160. Combined with the thermal mechanical processing technology of titanium alloy, when the temperature of hot processing and recrystallization is lower than the β transition temperature, or slowly cooling, high volume fraction of primary α phase and intergranular β will be obtained, recrystallization treatment at close to the β transition temperature will obtain equiaxial primary α phase uniformly distributed on the β matrix, which is represented by A1-A9 in the standard spectrum. After recrystallization above the β phase transition temperature, continuous grain boundary α, network α and lamellar α phases are obtained between the coarse β grains, which are manifested as A10-A24 in the standard diagram.

Key words: TC4 alloy, microstructure, domestic and foreign standards, heat treatment

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