▎ 摘　　要

NOVELTY - The graphene-based steel tubes, pipes or risers (BB) comprise essential alloying elements including 0.01-0.3 wt.% of aluminum, 0.01-2.0 wt.% of cobalt, 0.01-2.0 wt.% of copper, 0.1-18.0 wt.% of chromium, 0.1-3.0 wt.% of manganese, 0.1-0.6 wt.% of molybdenum, 0.1-3.0 wt.% of nickel, 0.01-0.8 wt.% of silicon, 0.1-3.0 wt.% of tungsten, 0.01-0.1 wt.% of vanadium. 0.8 wt.% of nitrogen, 0.25 wt.% of niobium, 0.006 wt.% of calcium, and 0.03 wt.% of titanium are also included. USE - Graphene-based steel tubes, pipes or risers used for conveying petroleum, gas and biofuels, for use in underwater riser systems for deep water with a direct application in petroleum industry, and for use as a component of complex product, such as pipelines, gas pipelines, rigid or flexible risers, subsea connections, tubular connections in different shapes, columns, wells, oil storage tanks, oil production structures, drilling platforms, semi-submersibles, helipads, towers or mobile offshore drilling units. (all claimed). ADVANTAGE - The graphene-based steel tubes, pipes or risers comprise aluminum, cobalt, copper and chromium, and thus ensures improved characteristics of geometry, chemical composition, microstructure and mechanical properties, like resistance to plastic deformation and residual stress profile with reduced crack propagation, improved surface cleaning and enhanced adhesion of coating layer. DETAILED DESCRIPTION - The graphene-based steel tubes, pipes or risers comprise essential alloying elements including 0.01-0.3 wt.% of aluminum, 0.01-2.0 wt.% of cobalt, 0.01-2.0 wt.% of copper, 0.1-18.0 wt.% of chromium, 0.1-3.0 wt.% of manganese, 0.1-0.6 wt.% of molybdenum, 0.1-3.0 wt.% of nickel, 0.01-0.8 wt.% of silicon, 0.1-3.0 wt.% of tungsten, 0.01-0.1 wt.% of vanadium. 0.8 wt.% of nitrogen, 0.25 wt.% of niobium, 0.006 wt.% of calcium, and 0.03 wt.% of titanium are also included. The graphene-based chemical composition has a carbon content between 0.01-21.0 wt.%, which is functionalized with functional groups including poly -COOH, -NO, -NH2, -CN, -CCH, -CH3, -CaC6, YbC6, -C60H2, -OH, -H, -F, -HCl, -HF, -F2 or -NHNH2. The graphene-based chemical composition has a microstructure with average grain size of 50-500 nu m formed by nano-sheets of graphene, ferrite, austenite, iron carbide, perlite, martensite, carbon nanotube, carbon fibers, nanodiamond, fullerenes, graphite or their mixtures. The graphene-based steel tubes have a wall thickness of 800 nm and 80 mm, and a diameter of 10-5000 mm, which cross section is elliptical, triangular, square, rectangular, pentagonal, hexagonal or other polyhedral geometry. The graphene-based steel tubes have a sandblasted surface by graphene granules or with other granules like aluminum, silicon, titanium, chromium, tungsten carbide or diamond. An INDEPENDENT CLAIM is included for a method for manufacturing graphene-based steel tubes, pipes or risers, which involves: (A) preparing a powder mixture of graphene, iron ores and alloy elements; (B) sintering heat treatment of the mixture at 1000-3773 degrees C; (C) shaping tubular geometry through hot or cold process with a predetermined wall thickness; and (D) finishing surface with granules of graphene or combination with other granules. DESCRIPTION OF DRAWING(S) - The drawing shows a schematic flowchart of the method for manufacturing graphene-based steel tubes, pipes or risers. (Drawing includes non-English language text). Preparing powder mixture (1) Sintering heat treatment (2) Shaping tubular geometry (3) Finishing surface (4) Product (AA) Graphene-based steel tubes, pipes or risers (BB)