炭素鋼の大形ねじり疲労試験

抄録

We have carried out some torsional fatigue tests, in order to research mainly on the effect of size with large bar type specimens of 50-70mm in diameter and with conventional small specimens of 7mm. The tested materials are 0.2% carbon forged steel, which consists of two charges, one is an acid open furnace steel and the other is an electric furnace steel. As the test results the following aspects were obtained mainly on the size effect.
The fatigue limit of these materials with large specimens fell within the range of 1.36-1.40kg per sq. mm, and was lower as compared with that with small specimens as to both charge steels, that is, 4.9% in the acid open furnace steel and 14.6% in electric furnace steel. It was found that even if the materials are made according to the same order standard and have the same mechanical and chemical properties, the metallurgical procedure of materials gives remarkable effects on the fatige strength, especially on the size effect.