抄録
In this experimental research, the authors carried out fatigue tests to examine the effect of various kinds of electrodes on the fatigue strength of welded specimens. Two series of specimens were used; one is of high tensile strength structural steels jointed together and the other is of high tensile strength structural steel connected with mild steel. Each of the two is provided with two types of filled welded joints, side fillet and front fillet respectively. The electrodes used are D5216, D4316 and D4301 electrodes.
For fatigue testing two kinds of the Losenhausen fatigue testing machines were used, that is, UHS type (capacity: static load 35 tons, dynamic load 20 tons) and UHP type (capacity: static load 20 tons, dynamic load 10 tons), and the repetition speed of both machines was 800 cycle/min.
The results of the fatigue tests, plotted in log-log scale, gives the S-N diagram, which indicates the slope is more steeply than that of the high tensile strength structural steel trially manufactured by the JSTM.
The values of σ100000, σ600000 and σ2000000 were computed from the results of the tests.
It was shown from these that each of the electrodes used was sufficiently strong in the fatigue strength of the welded joints of high tensile strength steel.
And a little differences were recongnized between the two series of specimens one has the splice platas of high tensile strength structural steel, and the other has the mild steel one.
The fatigue strength of side fillet welded joint was very small in these tests and this can be explained by the fact that the fatigue fracture under the lower pulsating stresses did not occur at the welded part of specimen, but occured at the spliced part.
