Fatigue Strength of Electron Beam Welded Joint of SGV49 Steel

Fatigue strength characteristics at room temperature were investigated for the base metal and electron beam welded joints of SGV49 steel. In load-controlled high cycle fatigue tests, the effects of reinforcement and stress relieved annealing were compared. In strain-controlled low cycle fatigue tests, on the other hand, fatigue strength between the base metal and welded jioint without reinforcement were compared. The results are suzmnarized as follows: (1)The high cycle and low cycle fatigue strength cbaracteristics were made clear for the electron beam welded joints of SGV49 steel. (2)The fatigue strength of the electron beam welded joints in the high cycle region is higher than those of the schielded arc welded joints and submerged arc welded ones. (3)The high cycle fatigue strength is improved due to the stress relieved annealing which has an effect to reduce the residual stress of welded joint. (4)All the fatigue cracks in the welded joints without reinforcement are observed at the base metal, because strain concentration in the base metal were occurred due to the different material characteristics of the base metal and weld metal. In the low cycle region, moreover, the fatigue curve for the base metal agrees well with that for welded joint using strain concentration factors.