高力ボルトの遅れ破壊の簡易じん速試験法
1993 年 42 巻 478 号 p. 855-860
詳細
1993 年 42 巻 478 号 p. 855-860
The purpose of this study is to establish a simple and rapid test method which can be used to investigate the possibility of occurrence of delayed fracture in high strength bolts. In this test, a specimen is immersed in hydrochloric acid (HCl) solution for some minutes under a tensile loaded condition with a load cell which is able to measure the clamping force, and then, the tensile test is perfomed after removing the specimen from the load cell.
The main results are as follows:
(1) It is necessary to finish the test within 30 minutes after acid dipping when the following test condition is used: the clamping force at 65% of tensile strength, 20% HCl solution temperature at 40°C and the dipped time for 40 minutes.
(2) The possibility of occurrence of delayed fracture can be estimated by the ratio of tensile strength before and after acid dipping. As the result of this study, the strength ratio was lower than 0.8 for all the bolts in which the delayed fracture is said to occur.
(3) In the range of tensile speed used (0.25-2.0mm), the tensile strength ratio was not affected by the tensile speed.
