Embodiments of the present disclosure are directed to coiled steel tubes and methods of manufacturing coiled steel tubes. In some embodiments, the final microstructures of the coiled steel tubes across all base metal regions, weld joints, and heat affected zones can be homogeneous. Further, the final microstructure of the coiled steel tube can be a mixture of tempered martensite and bainite.

Embodiments of the present disclosure are directed to coiled steel tubes and methods of manufacturing coiled steel tubes. In some embodiments, the final microstructures of the coiled steel tubes across all base metal regions, weld joints, and heat affected zones can be homogeneous. Further, the final microstructure of the coiled steel tube can be a mixture of tempered martensite and bainite.

The present invention relates to a steel alloy with high energy absorption capacity and good formability, comprising beside inevitable impurities due to smelting and iron the following components in weight percent: C 0.05-0.6% Sum of Cr+2*Ti+3*(Mo+V+Nb)+4*W=2-7%,
wherein the structure of the steel alloy comprises beside martensite portions of 10-40 Vol.-% retained austenite, wherein the energy absorption capacity expressed by the product of tensile strength (Rm) and uniform strain (Ag) is higher than 12,000 MPa % and the steel alloy has a minimal tensile strength of 1000 MPa. In addition, the invention relates to a steel tube product with high energy absorption capacity and good formability, which is characterized in that it at least partially consists of such a steel alloy.

The present invention relates to a steel alloy with high energy absorption capacity and good formability, comprising beside inevitable impurities due to smelting and iron the following components in weight percent: C 0.05-0.6% Sum of Cr+2*Ti+3*(Mo+V+Nb)+4*W=2-7%,
wherein the structure of the steel alloy comprises beside martensite portions of 10-40 Vol.-% retained austenite, wherein the energy absorption capacity expressed by the product of tensile strength (Rm) and uniform strain (Ag) is higher than 12,000 MPa % and the steel alloy has a minimal tensile strength of 1000 MPa. In addition, the invention relates to a steel tube product with high energy absorption capacity and good formability, which is characterized in that it at least partially consists of such a steel alloy.

A component manufacturing method includes: disposing, in a fluid, an unprocessed component having a hole that has an opening in an outer surface of the unprocessed component; creating a flow of the fluid such that air bubbles resulting from laser peening performed by irradiating an inner wall of the hole of the unprocessed component with a laser beam in the fluid flow along the hole; setting an irradiation area of the laser beam in an inner surface of the hole; and in the fluid of which the flow has been created, irradiating the irradiation area with the laser beam from the side of the outer surface through the opening.

A component manufacturing method includes: disposing, in a fluid, an unprocessed component having a hole that has an opening in an outer surface of the unprocessed component; creating a flow of the fluid such that air bubbles resulting from laser peening performed by irradiating an inner wall of the hole of the unprocessed component with a laser beam in the fluid flow along the hole; setting an irradiation area of the laser beam in an inner surface of the hole; and in the fluid of which the flow has been created, irradiating the irradiation area with the laser beam from the side of the outer surface through the opening.

A steel pipe for a fuel injection pipe has a chemical composition consisting of, by mass %: C: 0.17 to 0.27%, Si: 0.05 to 0.40%, Mn: 0.30 to 2.00%, P: 0.020% or less, S: 0.0100% or less, O: 0.0040% or less, Ca: 0.0010% or less, Al: 0.005 to 0.060%, N: 0.0020 to 0.0080%, Ti: 0.005 to 0.015%, Nb: 0.015 to 0.045%, Cr: 0 to 1.00%, Mo: 0 to 1.00%, Cu: 0 to 0.50%, Ni: 0 to 0.50%, V: 0 to 0.15%, and the balance: Fe and impurities. The metal micro-structure consists substantially of tempered martensite, or tempered martensite and tempered bainite. A prior-austenite grain size number is 9.0 or more. The hardness is within the range of 350 to 460 HV1. When a maximum value of a square root of an area of inclusions observed in a cross section perpendicular to a longitudinal direction of the steel pipe is taken as a.sub.n (n=1 to 20), a maximum value a.sub.max of a.sub.n is 30.0 μm or less, and an average value a.sub.av of a.sub.n is 40% or more of a.sub.max.

A steel material according to the present disclosure has a chemical composition consisting of, in mass %: C: 0.20 to 0.45%, Si: 0.05 to 1.00%, Mn: 0.01 to 1.00%, P: 0.030% or less, S: 0.0050% or less, Al: 0.005 to 0.100%, Cr: 0.60 to 1.50%, Mo: more than 1.00 to 2.00%, Ti: 0.002 to 0.020%, V: 0.05 to 0.30%, Nb: 0.005 to 0.100%, B: 0.0005 to 0.0040%, N: 0.0100% or less, O: less than 0.0020%, and the balance being Fe and impurities, and satisfying Formula (1) described in the specification. A grain diameter of a prior-austenite grain is 11.0 μm or less, and an average area of precipitate which is precipitated in a prior-austenite grain boundary is 10.0×10.sup.−3 μm.sup.2 or less. A yield strength is 758 to 862 MPa.

A steel material and methods for producing the same. The steel material exhibits excellent hydrogen embrittlement resistance in a high-pressure hydrogen gas environment and is, therefore, suitable for use in hydrogen storage tanks, hydrogen line pipes, and the like. The steel material has a specified chemical composition, a tensile strength of 560 MPa or higher, and a fracture toughness value K.sub.IH exhibited by the steel material in a high-pressure hydrogen gas atmosphere is 40 MPa.Math.m.sup.1/2 or higher.

The present disclosure relates to methods and treatments of linepipe steels that transport one or both of crude oil and natural gas. More particularly, the present disclosure relates to sulfide stress cracking resistance of carbon steels for use as linepipe in transporting crude oil and natural gas by alternative thermo-mechanically controlled and/or one or more additional heat treatment processes.