中文摘要：

以10MW高温气冷实验堆（HTR-10）内的结构石墨IG-11为研究对象，在石墨砖的不同位置沿正交方向取样，在1900℃下进行退火处理以消除试样内的残余应力，随后对两个正交方向上的试样分别预加载25MPa和35MPa的压缩应力，载荷保持2min后卸载，测量试样在35～500qc内的线性热膨胀系数（CTE），与未加载试样对比发现，预加载应力对石墨IG-11的热膨胀行为有着显著影响，预加载后石墨IG-11的轴向（平行于加载方向）平均CTE明显增大，且预加载应力越大，石墨试样的平均CTE增幅越大。预加载应力后石墨IG-11的平均CTE仍保持各向同性。预加载应力对石墨IG-11热膨胀行为的影响可能主要与应力作用下石墨内部微裂纹的闭合有关。

英文摘要：

Specimens were taken along two orthogonal directions of the IG-11 graphite brick, which was used as the structural graphite in 10 MW high temperature gas-cooled reactor （HTR-10）. After annealing at 1 900 ℃ for 2 hours to relieve the internal stresses, the specimens were pre-stressed with compressive stresses of 25 MPa and 35 MPa for 2 minutes, respectively. The coefficients of thermal expansion （CTE） of the pre-stressed specimens in the temperature range of 35 to 500 ℃ were measured, and the results showed that the pre-stressing had great influences on the thermal expansion behavior of graphite IG-11. Compared with those of the specimens without loading, the average axial （parallel to the loading direction）CTE increased significantly, and increased gradually with the increasing pre-stressed stresses. The CTE anisotropy of the pre-stressed graphite IG-11 still kept isotropic. The CTE changes of graphite IG-11 after pre-stressing were probably due to the closure of micro-cracks induced by the stresses in graphite.