ULTRA HIGH STRENGTH WELDING JOINT OF 950MPA GRADE HAVING EXCELLENT LOW TEMPERATURE TOUGHNESS

摘要

A welding joint having more than 950MPa of tensile strength is provided to control a range of a carbon equivalent formula for a welding metal in order to secure ultra high tensile strength more than 950MPa as well as high toughness at a low temperature. A welding joint having more than 950MPa of tensile strength comprises the following components. A welding metal composed of a base metal and a filler metal satisfies a carbon equivalent value(Ceq) of the following formula in a range from 0.7% to 0.8%. Ceq=[C]+[Mn]/6+([Cr]+[Mo]+[V])/5+([Ni]+[Cu])/15. The welding metal comprises more than 60 area% of acicular ferrite, bainite, 10~20 area% of martensite.