WELDED JOINT PART EXCELLENT IN TOUGHNESS AT VERY LOW TEMPERATURE AND ITS MANUFACTURE

摘要

PROBLEM TO BE SOLVED: To improve the toughness of a joint part at very low temperatures in a welded structure to be used at the very low temperatures. SOLUTION: This welded joint part excellent in toughness at very low temperatures is characterized in that one or more pores of 0.03 mm or above are left in the welded joint part per 1 cm2 in its cross-section of the thickness direction of a joint part, and an area factor occupied by the pores is 10% or below in the above cross-section. Thus the progress of a crack is blocked since the fine pores existing in the joint part make the radius of curvature at the tip of the crack larger, and the toughness of the joint part is remarkably improved.