Patent ID: 8323560

Claim:
A high-strength electric resistance welded steel pipe comprising: 0.2 to 0.4 percent by mass carbon (C), 0.05 to 0.5 percent by mass silicon (Si), 0.5 to 2.5 percent by mass manganese (Mn), 0.025 percent by mass of less phosphorus (P), 0.01 percent by mass of less sulfur (S), 0.01 to 0.15 percent by mass aluminum (Al), 0.01 to 2 percent by mass copper (Cu), 0.05 to 2 percent by mass chromium (Cr), 0.005 to 0.2 percent by mass titanium (Ti), and 0.0002 to 0.005 percent by mass boron (B), wherein the steel pipe has a tensile strength of 1750 N/mm 2 or more, a 0.1%-proof stress of 1350.8 N/mm 2 or more, a ratio of said 0.1%-proof stress to said tensile strength of 75.3% or more, and a Charpy impact value at a testing temperature of minus 40° C. of 50 J/cm 2 or more.