论文部分内容阅读
采用电解渗氢法制备出氢含量为60mg/g的压力管材料Zr-2.5Nb合金。利用X射线衍射仪(XRD)、金相显微镜(OM)、透射电子显微镜(TEM)研究了Zr-2.5Nb合金微观结构,采用扫描电镜(SEM)观察了Zr-2.5Nb合金氢致延迟开裂(DHC)断口形貌。结果表明:Zr-2.5Nb合金基体为密排六方结构的a-Zr相,远离裂纹尖端区域晶粒较大(大于5mm),裂纹尖端对应区域的基体晶粒较小(1mm左右);面心立方结构δ-ZrH_(1.66)呈条片状平行于轧制方向分布;体心立方结构的第二相Nb颗粒尺寸为50~500 nm,在晶粒内部均匀分布,晶界附近成串状分布;试验温度为250℃时,预制疲劳裂纹平行于轧制方向的试样,裂纹呈现步进式生长,每步生长的距离大致相当于氢化物的尺寸,约为20mm。
Hydrogen gas pressure was used to prepare Zr-2.5Nb alloy tube with hydrogen content of 60mg / g. The microstructure of Zr-2.5Nb alloy was investigated by X-ray diffraction (XRD), optical microscope (OM) and transmission electron microscopy (TEM). The delayed induced cracking of Zr-2.5Nb alloy was observed by scanning electron microscopy DHC) fracture appearance. The results show that the matrix of the Zr-2.5Nb alloy is a-Zr hexagonal close-packed a-Zr phase with larger grains (greater than 5mm) away from the crack tip region and smaller matrix grains (about 1mm) in the crack tip region. The cubic structure of δ-ZrH_ (1.66) was distributed in the form of strips parallel to the rolling direction. The second phase of the body-centered cubic structure was composed of 50-500 nm Nb particles and was uniformly distributed in the grains. When the test temperature is 250 ℃, the specimens with the fatigue crack parallel to the rolling direction are prefabricated. The cracks show a step-by-step growth. The distance of each step grows roughly the size of the hydride, which is about 20mm.