ROOM TEMPERATURE CREEP BEHAVIOR AND ITS EFFECT ON TENSILE PROPERTIES OF CP-TI

Commercial pure titanium (CP-Ti) is an attractive material, due to its good properties such as high strength, high specific work hardening ability, excellent plasticity, toughness, corrosion resistance and weld ability. It is commonly used in pressure vessels, such as heat exchangers, pumps, valves and so on. It has been reported that the room temperature creep has a great influence on the failure of titanium pressure vessel. In this paper, in order to investigate room temperature creep behavior and its effect on tensile properties of CP-Ti, both creep and tensile experiments were carried out. According to creep experiment results, CP-Ti shows strong stress dependent creep behavior at the creep stress higher than 305MPa. On the contrary, the strong loading rate dependent creep behavior occurs at the creep stress lower than 305MPa. Besides, creep strain of CP-Ti can be reduced by pretension. As pretension reaches 6%, creep behavior of CP-Ti is completely suppressed at the creep stress of 320MPa. Subsequent tensile test results show that the occurrence of room temperature creep obviously enhances the strength of CPTi. With the increase of creep strain and loading rate in previous creep tests, the yield strength and tensile strength of CP-Ti increase.