LOW YIELD RATIO DUAL PHASE STEEL LINEPIPE WITH SUPERIOR STRAIN AGING RESISTANCE

• Main Authors: FAIRCHILD DOUGLAS P, LEBLEU JAMES B. JR, OZEKCIN ADNAN, JIN, HYUN WOO, AYER RAGHAVAN, KOO JAYOUNG, OKATSU MITSUHIRO, BANGARU NARASIMHA V, ENDO SHIGERU, HOYT DOUGLAS S, BEESON DANNY L, KAKIHARA SHINICHI
• Format: Patent
• Language: English
• Published: 20.07.2009
• Subjects: ALLOYS; CHEMISTRY; FERROUS OR NON-FERROUS ALLOYS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; TREATMENT OF ALLOYS OR NON-FERROUS METALS

A steel composition and method from making a dual phase steel therefrom. In at least one embodiment, the dual phase steel comprises carbon in an amount of about 0.05% by weight to about 0.12 wt%; niobium in an amount of about 0.005 wt % to about 0.03 wt%; titanium in an amount of about 0.005 wt% to about 0.02 wt%; nitrogen in an amount of about 0.001 wt% to about 0.01 wt%; silicon in an amount of about 0.01 wt% to about 0.5 wt%; manganese in an amount of about 0.5 wt% to about 2.0 wt%; and a total of molybdenum, chromium, vanadium and copper less than about 0.15 wt%. The steel has a first phase consisting of ferrite and a second phase comprising one or more constituents selected from the group consisting of carbide, pearlite, martensite, lower bainite, granular bainite, upper bainite, and degenerate upper bainite. A solute carbon content in the first phase is about 0.01 wt% or less.