Abstract: A steel composition and method from making a dual phase steel therefrom. The dual phase steel may have carbon of about 0.05% by weight to about 0.12 wt %; niobium of about 0.005 wt % to about 0.03 wt %; titanium of about 0.005 wt % to about 0.02 wt %; nitrogen of about 0.001 wt % to about 0.01 wt %; silicon of about 0.01 wt % to about 0.5 wt %; manganese 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 may have a first phase consisting of ferrite and a second phase having one or more of carbide, pearlite, martensite, lower bainite, granular bainite, upper bainite, and degenerate upper bainite. A solute carbon content in the first phase may be about 0.01 wt % or less.

Abstract: Provided are metal structures and methods of forming such structures for use in oil, gas and/or petrochemical applications that are joined with non-ferrous weld metal compositions or a high alloy weld metal compositions. The welded metal structures include two or more segments of ferrous or non-ferrous components, and fusion welds, friction stir welds or a combination thereof bonding adjacent segments of the components together, wherein the welds comprise a non-ferrous weld metal composition or a high alloy weld metal composition that is substantially different from the metal composition of the two or more components. The resultant welded structures exhibit improvements in fatigue resistance, toughness, strain capacity, strength, stress corrosion cracking resistance, and hydrogen embrittlement resistance compared to traditional iron-based weld compositions.

Abstract: The use of friction stir and laser shock processing in oil & gas and/or petrochemical applications is provided by the present invention. The use includes subjecting friction stir weldments, fusion weldments, and other critical regions of ferrous and non-ferrous alloy components used in oil & gas and petrochemical applications to laser shock processing to create residual compressive stresses near the surface of the treated area. The residual compressive forces in the ferrous or non-ferrous components improve properties including, inter alia, surface strength, fatigue life, surface hardness, stress corrosion resistance, fatigue resistance, and environmental cracking resistance. Friction stir and laser shock processing find particular application in high strength pipelines, steel catenary risers, top tension risers, threaded components, liquefied natural gas containers, pressurized liquefied natural gas containers, deep water oil drill strings, riser/casing joints, and well-head equipment.

Abstract: A method for welding and repairing cracks in metal parts is provided by subjecting the metal parts to be welded to friction stir welding and the cracks to be repaired to friction stir processing under conditions sufficient to provide a weld joint or crack repair having a preselected property or set of properties based upon the intended use of the weldment.

Abstract: Methods of welding two pieces of metal to produce a weld joint having excellent fracture toughness are provided. Two pieces of metal are positioned for welding so as to form a narrow weld groove having two sidewalls with bevel angles of less than about 10°. Two or more layers are applied to the weld groove to produce the weld joint such that the heat-affected-zone of the weld joint is substantially free of rogue grains.

Abstract: Methods of welding two pieces of metal to produce a weld joint having excellent fracture toughness are provided. Two pieces of metal are positioned for welding so as to form a narrow weld groove having two sidewalls with bevel angles of less than about 10°. Two or more layers are applied to the weld groove to produce the weld joint such that the heat-affected-zone of the weld joint is substantially free of rogue grains.

Abstract: Weld metals suitable for joining high strength, low alloy steels are provided. These weld metals have microstructures of acicular ferrite interspersed in a hard constituent, such as lath martensite, yield strengths of at least about 690 MPa (100 ksi), and DBTTs lower than about −50° C. (−58° F.) as measured by a Charpy energy versus temperature curve. These weld metals include about 0.04 wt % to about 0.08 wt % carbon; about 1.0 wt % to about 2.0 wt % manganese; about 0.2 wt % to about 0.7 wt % silicon; about 0.30 wt % to 0.80 wt % molybdenum; about 2.3 wt % to about 3.5 wt % nickel; about 0.0175 wt % to about 0.0400 wt % oxygen, and at least one additive selected from the group consisting of (i) up to about 0.04 wt % zirconium, and (ii) up to about 0.02 wt % titanium.

Abstract: Girth welds with crack arresting capability, and welding methods for producing same in high strength pipelines, are provided. Girth welds according to this invention are produced in high strength pipelines by welding methods that produce (i) HAZ microstructures that are softer than the pipeline steels, (ii) weld toes that act as stress/strain concentrators, thus promoting tearing in the HAZ and a ring-off fracture; and (iii) a weld geometry that promotes an inclined fracture path.

Abstract: Weld metals suitable for joining high strength, low alloy steels are provided. These weld metals have microstructures of acicular ferrite interspersed in a hard constituent, such as lath martensite, yield strengths of at least about 690 MPa (100 ksi), and DBTTs lower than about −50° C. (−58° F.) as measured by a Charpy energy versus temperature curve. These weld metals include about 0.04 wt % to about 0.08 wt % carbon; about 1.0 wt % to about 2.0 wt % manganese; about 0.2 wt % to about 0.7 wt % silicon; about 0.30 wt % to 0.80 wt % molybdenum; about 2.3 wt % to about 3.5 wt % nickel; about 0.0175 wt % to about 0.0400 wt % oxygen, and at least one additive selected from the group consisting of (i) up to about 0.04 wt % zirconium, and (ii) up to about 0.02 wt % titanium.

Abstract: Welding methods are provided for use in joining ultra-high strength, low alloy steels to produce weldments having tensile strengths greater than about 900 MPa (130 ksi) with weld metals having fracture toughness suitable for cryogenic applications according to known principles of fracture mechanics.

Abstract: A container is provided for storing pressurized liquefied natural gas at a pressure of about 1035 kPa (150 psia) to about 7590 kPa (1100 psia) and at a temperature of about -123.degree. C. (-190.degree. F.) to about -62.degree. C. (-80.degree. F.). The container is constructed from an ultra-high strength, low alloy steel containing less than 9 wt % nickel and having a tensile strength greater than 830 MPa (120 ksi) and a DBTT lower than about -73.degree. C. (-100.degree. F.).

Abstract: A method for determining the relative HAZ toughness of steel. The method comprises determining at least two thermal cycles of the steel for at least one weld heat input value and then simulating the HAZ that would result if the steel were actually welded in accordance with those thermal cycles. The steel is then fractured to determine various fracture properties, each of which may be used to determine the midpoint transition temperature associated with the fracture property used. The midpoint transition temperature is compared to a previously determined standard maximum midpoint transition temperature and if it is greater than the standard, the steel may have low HAZ toughness, but if it is less than the standard, the steel may have a high HAZ toughness.