镍基单晶高温合金冷热循环过程中圆孔周围裂纹萌生与扩展行为

发布时间：2018-04-21 05:01

  本文选题：镍基单晶高温合金 + 晶体学取向　； 参考：《金属学报》2015年10期

【摘要】：选用第二代镍基单晶高温合金,制备了平行于定向凝固方向且分别沿(100)面和(110)面的2组板式试样,采用电火花方法在试样中心垂直于板面加工孔径为0.5 mm的圆孔.采用室温到1100℃的冷热疲劳实验,研究了冷热循环过程中不同晶体学平面的板式试样上圆孔周围裂纹萌生及扩展行为.结果表明,位于不同晶体学平面的板式试样中,电火花方法加工圆孔周围产生了一薄层再铸层,再铸层最厚处约15 μm.板式试样所在晶体学平面对圆孔周围裂纹萌生及扩展行为影响显著.冷热循环80 cyc后,(110)面试样中,裂纹在与枝晶生长方向垂直的孔边产生,之后迅速沿与枝晶生长方向呈45°角扩展.而对于(100)面试样,即使经过200 cyc冷热循环后孔边也未观察到裂纹,造成此差异的本质原因是单晶高温合金晶体结构的各向异性导致的热应力差别与微观组织特征共同作用的结果.
[Abstract]:Two groups of plate specimens, parallel to the directional solidification direction and along the plane of 100 and 110), were prepared by using the second generation nickel base single crystal superalloy. The holes with a diameter of 0.5 mm perpendicular to the plate surface were machined by EDM method in the center of the specimen. The initiation and propagation behavior of cracks around circular holes in plate specimens with different crystallographic planes during cold and thermal cycling were studied by means of cold and thermal fatigue tests from room temperature to 1100 鈩，

本文编号：1781015