微织构对Ti-6Al-3Nb-2Zr-1Mo合金的应力腐蚀性能的影响

Effect of Microtexture on the Stress Corrosion Property of Ti-6Al-3Nb-2Zr-1Mo Alloy

  • 摘要: 采用EBSD方法对断口以及裂纹扩展路径进行观察,研究了近α型钛合金Ti-6Al-3Nb-2Zr-1Mo组织中的微织构对应力腐蚀敏感性和裂纹扩展路径的影响规律。结果表明,微织构区域的形貌为接近平行于轧面的不规则薄片层状,长度方向沿轧向扩展,微织构区的晶粒取向为c轴趋近于与板材横向平行。当加载方向与微织构区的长度方向接近平行时,微织构区内部晶粒易于柱面滑移,降低裂纹尖端的应力集中和降低应力腐蚀敏感性;当加载方向与微织构区的长度方向接近垂直时,微织构区内部晶粒不容易发生柱面滑移和基面滑移,易于造成局部应力集中和形成微裂纹,提高板材的应力腐蚀敏感性。

     

    Abstract: The influence of microtexture on the stress corrosion cracking susceptibility and crack propagation path of a near alpha titanium alloy Ti-6 Al-3 Nb-2 Zr-1 Mo were investigated by the observation of the fracture surfaces and the crack propagating paths using EBSD method. The results showed that the morphologies of the microtexture zones were irregular thin lamellae which were nearly parallel to the rolling plane, with their longitudinal direction extending along the rolling direction, and that the grain orientation in the microtexture zones was their c-axis almost parallel to the transverse direction of the bulk plate. When the loading direction was almost parallel to the longitudinal directions of the microtexture zones, prismatic slip was easily activated in the grains of these zones, so as to decrease the stress concentration at crack tip as well as the stress corrosion cracking susceptibility. When the loading direction was almost perpendicular to the longitudinal directions of microtexture zones, prismatic slip and basal slip were hard to activate and that would lead to localized stress concentration and the formation of micro-cracks, raising the stress corrosion cracking susceptibility of the plate.

     

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