Submerged arc welded metal joint having excellent low temperature toughness and low hardness and welded steel pipe have the same

摘要

The present invention provides a submerged arc welded metal part having excellent low-temperature toughness and low hardness characteristics. According to an embodiment of the present invention, the submerged arc weld metal portion, by weight, carbon (C): 0.05 to 0.1%, silicon (Si): 0.2 to 0.7%, manganese (Mn): 0.8 to 1.2 %, Chromium (Cr): >0 to 0.1%, Nickel (Ni): 0.05 to 0.15%, Molybdenum (Mo): >0 to 0.01%, Niobium (Nb): >0 to 0.03%, Titanium (Ti): 0.01 to 0.025%, boron (B): 0.0005 to 0.0025%, phosphorus (P): more than 0 to 0.02%, sulfur (S): more than 0 to 0.01%, and the balance contains iron (Fe) and other unavoidable impurities and Mn [wt%] + 5Si [wt%] + 8Ni [wt%] + 20Mo [wt%] is controlled to be 3.5 or more to 4.5 or less.