Patents by Inventor Kuniaki Tomomatsu

Kuniaki Tomomatsu has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Publication number: 20090098403
    Abstract: A low alloy steel is provided for oil country tubular goods with a yield strength between 654 MPa and 757 MPa, and possessing excellent resistance to HIC and SSC in high-pressure hydrogen sulfides environment, and comprising, by mass %: 0.10 to 0.60% C; 0.05 to 0.5% Si; 0.05 to 3.0% Mn; 0.025% or less P; 0.010% or less S; 0.005 to 0.10% Al; 0.01% or less O (oxygen); 3.0% or less Cr; and 3.0% or less Mo, wherein the amount of Cr and Mo content is 1.2% or more, with the balance being Fe and impurities, and the number of nonmetallic inclusions whose major axis is 10 ?m or more is 10 per square millimeter in the inspected cross section. The present invention provides a low alloy steel for oil country tubular goods possessing excellent resistance to sulfide stress cracking, and a seamless steel pipe.
    Type: Application
    Filed: September 16, 2008
    Publication date: April 16, 2009
    Inventors: Tomohiko Omura, Yuji Arai, Kuniaki Tomomatsu, Toshiharu Abe
  • Publication number: 20090047166
    Abstract: A low alloy steel comprising, by mass %, C: 0.10 to 0.20%, Si: 0.05 to 1.0%, Mn: 0.05 to 1.5%, Cr: 1.0 to 2.0%, Mo: 0.05 to 2.0%, Al: 0.10 % or less and Ti: 0.002 to 0.05%, and with a Ceq value obtained by the following formula (1) of 0.65 or more, with the balance being Fe and impurities, wherein in the impurities, P is 0.025% or less, S is 0.010% or less, N is 0.007% or less, and B is less than 0.0003%, and the number per unit area of M23C6 type precipitates (M: a metal element) whose grain diameter is 1 ?m or more is 0.1/mm2 or less. This invention provides a low alloy steel possessing both hardenability and toughness and improves the resistance to sulfide stress corrosion cracking. Ceq=C+(Mn/6)+(Cr+Mo+V)/5 ??formula (1) where C, Mn, Cr, Mo and V in the formula (1) denote the mass % of respective elements.
    Type: Application
    Filed: October 1, 2008
    Publication date: February 19, 2009
    Inventors: Kuniaki Tomomatsu, Tomohiko Omura, Yuji Arai, Toshiharu Abe