抄録
High temperature tensile tests were carried out at various displacement rates. The main results obtained are as follows.
(1) Fracture strength decreased sharply at temperatures beyond 1000°C.
(2) No non-linear load-displacement relation was observed at a displacement rate equal to 0.6mm/min at either 900°C or 1000°C. Under these test conditions, high temperature slow crack growth (H.T. SCG), which is creep damage, was not observed and fracture originated from the defects such as pores or inclusions.
(3) Non-linear load-displacement relation was observed at a displacement rate equal to or smaller than 0.06mm/min at 1100°C. Non-linear deformation increased as the displacement rate decreased. In this case, high temperature slow crack growth was observed and fracture originated mainly from high temperature SCG.
(4) Fracture strength at 900°C was dominated by either defects such as pores or high temperature damage. Softening of the glass phase due to O2- diffusion at this temperature may be attributable to this damage. Creep damage appeared at temperatures equal to or higher than 1100°C. At 1200°C, fracture strength was mainly dominated by creep damage.
