Abstract
The benavior of high strength bolted friction joints under high temperature was experimentally investigated. In this investigation four types of test specimen were used, where the ratio of the slip strength of the bolted joints to the yield strength of the jointed parts varied from 0.5 to 1.2, and the total number of the specimens was 70. The joints were subjected to the constant working load which varied from 50 to 95% of the slip load at the testing temperature respectively and the testing temperature was 300℃, 350℃, 400℃, 450℃, and 500℃, The holding time of the working load at high temperature was 1, 3 and 6 hours respectively. After evaluation of test results, following conclusion was obtained. The slip strength of the high strength bolted joint decreases, when it is subjected to the heat over 300℃. The state of this decreasing phenomenon of the slip strength is represented by bilinear line with good accuracy. The decrease of slip strength is considerablly small, when the heating temperature is less than 400℃. But the slip strength decreases violently, when the heating temperature is over 400℃. The constant working load and the heating time do not particurally affect to the decrease of the slip strength. Therefore it is considered that the main reason of this decrease of the slip strength of the heat affected high strength bolted joint depends upon the thermal relaxation of the bolt tension.
