고(高) Energy밀도용접(密度熔接)에 의(依)한 용접(熔接)이음에 있어서의 잔류응력(殘留應力)과 피로특성(疲勞特性)에 관(關)한 연구(硏究) -HT80강(鋼)의 전자(電子) Beam 용접(熔接)이음 피로강도(疲勞强度)-

Study on the Residual Stress and Fatigue Strength of Welded Joint by High Energy Density Welding -Fatigue Scrength of Welded Joint of HT80 Steel by Electron Beam Welding-

The versatile practical use of electron beam welding which is very high energy density is still in early stage, but in the special welding field, the welding process is used in manufactured goods. The investigation for electron beam welding up to the present was almost achieved not for the mechanical properties of welded joint but for the process itself. On this investigation, the fatigue strength, crack propergation phenomena and hardness of weld metal and heat affected zone of partially penetrated welded joint of HT80 steel by electron beam welding was accomplished. The tensile fatigue strength in weld line direction of the joint was about $25kg/mm^2$. There still appeared spikes on the tips of penetration, and the crack initiated at the tips of spikes not from the roots. The hardness of the weld metal was higher than it of base metal because of production of martensite by rapid cooling.