Technological mode progress demands the use of materials at high temperature and pressure. Constant load creep tests have been carried out over the range of stresses at high temperatures. One of the most critical factors in considering such applications as the most critical one is the creep behavior. In order to investigate the creep behavior in this study, the stress exponents during creep were determined over the temperature range of 275℃ to 325℃ and the stress range of 36MPa to 72MPa. The applicability of modified Monkman-Grant relationship was also discussed.