US Patent Issued to NIPPON STEEL on March 17 for "Composite tube and welded joint" (Japanese Inventors)

ALEXANDRIA, Va., March 17 -- United States Patent no. 12,577,646, issued on March 17, was assigned to NIPPON STEEL Corp. (Tokyo).

"Composite tube and welded joint" was invented by Hiroyuki Hirata (Tokyo), Mitsuru Yoshizawa (Tokyo), Katsuki Tanaka (Tokyo) and Takahiro Osuki (Tokyo).

According to the abstract* released by the U.S. Patent & Trademark Office: "A composite tube includes a first tube and a second tube. A chemical composition of the first tube includes, in mass %, C: more than 0.060% to 0.400% or less, Si: 0.01 to 1.00%, Mn: 0.01 to 1.20%, P: 0.0350% or less, S: 0.0150% or less, Sn: 0.0005 to 0.0400%, Al: 0.040% or less, N: 0.050% or less, O: 0.030% or less, and the balance: Fe and impurities. A chemical composition of the secon...