基于显微组织调控的Ti80合金强韧化机理研究

Study on Strengthening and Toughening Mechanisms of Ti80 Alloy Based on Microstructure Regulation

Ti80合金是由我国自主创新研制的耐蚀可焊近α型钛合金,海洋装备对Ti80合金的强度、塑性和冲击韧性提出了更高要求。通过调控退火温度得到Ti80合金等轴、双态和魏氏三种典型组织,对其进行力学性能测试,并采用SEM及EBSD技术阐明其演变规律和强韧化机理。结果显示:等轴α相优异的协调变形能力使等轴组织和双态组织具有优异的塑性,交错分布的α集束的协调变形能力差导致魏氏组织的塑性最差;魏氏组织的冲击吸收能量最高,三种组织冲击性能的差异主要来源于裂纹扩展功的不同;双态组织中等轴α相具有优异的塑性变形能力,片层α相具有较好的偏折裂纹作用和一定的塑性变形能力,因此,相对曲折的裂纹扩展路径以及沿着裂纹路径的良好塑性变形使其具有最优异的强度-塑性-冲击韧性匹配。

Ti80 alloy is a corrosion-resistant weldable near-αtitanium alloy independently developed by China.Marine equipment puts forward higher requirements for the strength,plasticity and impact toughness of Ti80 alloy.In this study,three typical microstructures of exquiaxial,duplex,and widmanstatten structures of Ti80 alloy are obtained by adjusting the annealing temperature,and the mechanical properties are tested.The evolution law and strengthening and toughening mechanism of Ti80 alloy are clarified by SEM and EBSD techniques.The results show that the excellent compatible deformation capability of the equiaxed ty of the interlacedαclusters leads to the poor plasticity of the Vermanchii structure.The impact energy absorbed by the Westmanstatten structure is the highest.The difference of the impact properties of the three structures is mainly due to the difference of crack propagation work.Theαphase of the duplex structure has excellent plastic deformation ability,and the lamellarαphase has good crack deflection action and certain plastic deformation ability.The relatively tortuous crack propagation path and good plastic deformation along the crack path make the duplex structure have the best strength,plasticity,and impact toughness.