As-rolled type K55 electric resistance welded oil well pipe and hot-rolled steel sheet

• Main Authors: Ishitsuka, Tetsuo, Tsusue, Takashi, Kobayashi, Shunichi, Ogata, Toshiyuki, Kawano, Hideto, Yoshida, Osamu, Iwamoto, Shuji
• Format: Patent
• Language: English
• Published: 11.08.2020
• Subjects: ALLOYS; CHEMISTRY; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; EARTH DRILLING; EARTH DRILLING, e.g. DEEP DRILLING; FERROUS OR NON-FERROUS ALLOYS; FIXED CONSTRUCTIONS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS; MACHINE TOOLS; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS; MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVINGMATERIAL; METAL-WORKING NOT OTHERWISE PROVIDED FOR; METALLURGY; METALLURGY OF IRON; MINING; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR ASLURRY OF MINERALS FROM WELLS; PERFORMING OPERATIONS; PUNCHING METAL; ROLLING OF METAL; SOLDERING OR UNSOLDERING; TRANSPORTING; TREATMENT OF ALLOYS OR NON-FERROUS METALS; WELDING; WORKING BY LASER BEAM

An as-rolled type K55 electric resistance welded oil well pipe includes, in terms of % by mass, 0.30 to 0.50% of C, 0.05 to 0.40% of Si, 0.50 to 1.20% of Mn, 0 to 0.030% of P, 0 to 0.020% of S, 0.002 to 0.080% of Al, 0 to 0.0080% of N, 0 to 0.30% of Cu, 0 to 0.30% of Ni, 0 to 0.30% of Cr, 0 to 0.10% of Mo, 0 to 0.10% of V, 0 to 0.050% of Nb, 0 to 0.030% of Ti, 0 to 0.0100% of Ca, and the balance being Fe and impurities. In the pipe, a metallographic structure at a position of ¼ of a pipe thickness in an L cross-section at a base metal 90° position is a ferrite-pearlite structure in which prior γ-grains are flattened, includes grain boundary ferrite and intragranular ferrite, and has a rate of a total area of the grain boundary ferrite and the intragranular ferrite, of 10 to 30%.