摘要:
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 μm 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.
摘要:
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 μm 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.
摘要翻译:1.一种低合金钢,以质量%计含有C:0.10〜0.20%,Si:0.05〜1.0%,Mn:0.05〜1.5%,Cr:1.0〜2.0%,Mo:0.05〜2.0%,Al:0.10% 较小,Ti:0.002〜0.05%,下述通式(1)所得的Ceq值为0.65以上,余量为Fe和杂质,其中,在杂质中,P为0.025%以下,S为0.010 %以下,N为0.007%以下,B小于0.0003%,粒径为1μm以上的M23C6型析出物(M:金属元素)的单位面积数为0.1个/ mm 2以下 。 本发明提供了具有淬透性和韧性两者的低合金钢,提高了耐硫化应力腐蚀开裂性。 Ce = C +(Mn / 6)+(Cr + Mo + V)/ 5式(1)<?in-line-formula description =“In-line formula”end =“lead” 式中,式(1)中的C,Mn,Cr,Mo和V表示各元素的质量%。