Rotating Bending Fatigue Tests on Ni-Cr-Mo Steel in the Plastic Range

Abstract

The constant stress and the constant deflection test were carried out of the rotating and bending fatigue of Ni-Cr-Mo steel cantilever in the plastic range at the frequency of 62rpm and at different temperatures, respectively at room temperature, at 350°C and at 550°C. In the constant stress test, the change of vertical and horizontal deflection at the loading end of the test specimen was observed. In the constant deflection test, the change of stress was also observed. The test results were discussed and compared with those obtained on the 0.35% carbon steels reported in the previous issue.The main conclusions of the results are as follows:1) It has been found in the constant stress test that the fatigue life is longest at room temperature, and falls respectively at 350°C and at 550°C. In the constant deflection test the fatigue life is approximately equal both at room temperature and at 350°C but remarkably falls at 550°C.2) The changes of deflection in the constant stress test and changes of stress in the constant deflection test have shown difference according to the temperature. On the whole they show opposite tendency.3) These results in both the tests have been compared based on the static bending test. The constant deflection is found stronger than the constant stress both at room temperature and at 350°C, but reverse at 550°C.