9 results about "Acicular ferrite" patented technology

The present application belongs to the technical field of hot stamping part preparation, and particularly relates to a tailor-welded part, a manufacturing method thereof and a welding wire applied to the tailor-welded part. The tailor-welded part comprises a welded joint, and a weld seam of the welded joint comprises acicular ferrite and martensite. The average length of the acicular ferrite is not greater than 80 microns, the average diameter is not greater than 15 microns, and the volume percentage of ferrite in the weld seam is 0.1-10%. The tailor-welded part is a part after hot stamping treatment. The joint elongation of the tailor-welded part is greater than 4%, the weld seam structure is martensite and ferrite, the fracture position is located in the base material during the quasi-static tensile test, and the weld seam has good strength and ductility.

This invention relates to the field of new energy infrastructure materials technology, and in particular to a high-strength weather-resistant steel for large-diameter monopile foundation structures and its preparation method. The invention utilizes the synergistic design and optimization of Nb and Ti microalloying elements, combined with controlled rolling and cooling processes, to effectively promote the formation of fine acicular ferrite and lower bainite structures and the dispersed precipitation of nano-reinforcing phases such as Ti(C,N) and Nb(C,N). While ensuring the alloy steel possesses high strength, high plasticity, and excellent corrosion resistance, it significantly reduces dependence on precious metal alloying elements such as Ni and Mo, resulting in outstanding cost-effectiveness. This steel can be used as a steel for wind power monopile foundations in harsh marine environments, solving the problems of low strength, poor corrosion resistance, and high cost in existing diameter monopile foundation structures.

The application discloses a low-cost large-heat-input welding method for common high-strength steel, selects common high-strength steel plates with thickness of 20mm-120mm and tensile strength of 450-650MPa as base materials, firstly melts thin-layer weld metal in a groove by small-line-energy gas shielded welding, forms fine and dispersed inclusions in the weld by Ti, Si, Al and Mn oxides and MnS complex, and induces generation of slender acicular ferrite (AF) structure, and then completes welding by vertical gas-electric vertical welding with large heat input, so that the thin-layer weld metal is used as new heat affected zone (HAZ), the inclusions inhibit austenite grain growth, and the AF structure is transformed into equiaxed ferrite. The application can realize large-heat-input efficient welding of common high-strength steel without special large-heat-input welding steel, the low-temperature impact toughness of each region of the joint is excellent, the material cost is greatly reduced, the welding efficiency is improved, and the application is suitable for thick plate welding fields such as shipbuilding and offshore platform.

This invention discloses a low-cost, thick-gauge, high-strength and high-toughness X70 pipeline steel and its production method. Its chemical composition is: C: 0.05–0.07%, Si: 0.15–0.25%, Mn: 1.70–1.85%, Nb: 0.035–0.055%, Ti: 0.030–0.045%, Cr: 0.30–0.35%, Ce: 0.0015–0.0035%, Als: 0.015–0.035%, S: ≤0.003%, P: ≤0.010%, N: ≤0.0035%. The production method includes smelting and continuous casting, heating and rolling, cooling, and coiling processes. Compared with existing technologies, this invention, without adding Mo or Ni, achieves uniform and fine acicular ferrite with a small amount of Mao island (M / A) or granular bainite structure through optimized design of elements such as Nb, Ti, and Ce, combined with comprehensive control of continuous casting and controlled rolling and cooling processes. Niobium-titanium nanoprecipitates further strengthen the ferrite, enabling the pipeline steel of this invention to not only have excellent mechanical properties, weldability, and low-temperature tear resistance, but also significantly reduce production costs, achieving good service safety and economy.

This invention relates to the field of local heat treatment and precise control of material microstructure in high-performance tunneling machine tool steel. It discloses a laser cladding process for drill bit alloy steel based on interface toughening treatment, comprising: constructing a cladding deposition layer on the surface of the alloy steel substrate using a main laser energy field; performing heat compensation on the fusion line region from the laser energy field; adjusting the output power from the laser energy field in real time according to the cumulative total input energy to offset the background temperature rise; controlling the physical residence time above the phase transformation temperature; adjusting the physical hysteresis distance and beam spot topology of the laser according to the local three-dimensional geometric curvature of the processed surface to reduce the local heat flux intensity; and solving the problem of phase transformation path runaway caused by background heat accumulation and thermal resistance accumulation in large thermally inert components by in-situ inducing the generation of a toughened microstructure interwoven with acicular ferrite and bainite, thereby improving interfacial impact toughness and achieving global microstructure isomorphism.

This invention relates to a 60-100mm thick SA537CL1 steel plate with excellent die-welding performance and its manufacturing method, belonging to the field of metallurgical technology. The chemical composition of the steel plate (wt%) is: C: 0.06-0.09%, Si: 0.25-0.50%, Mn: 1.40-1.60%, P≤0.010%, S≤0.003%, Ni: ≤0.10%, Mo: 0.05-0.08%, Nb: 0.010-0.030%, Ti: 0.010-0.030%, with the balance being Fe and unavoidable impurities, and a carbon equivalent (Ceq) ≤0.36%. The surface microstructure is bainite, the microstructure at 1 / 4 thickness position is acicular ferrite + pearlite, and the core microstructure is polygonal ferrite + pearlite + acicular ferrite. The manufacturing process is as follows: oxygen converter smelting → ladle furnace refining → vacuum treatment → thick slab continuous casting → billet cooling → billet heating → controlled rolling → controlled cooling → stacking and slow cooling.

The application discloses a long rod bolt heat treatment process and relates to the technical field of metal heat treatment. The long rod bolt heat treatment process steps of the application successively comprise ultrasonic cleaning, primary salt quenching, secondary salt quenching and tempering. The molten salt solution for the primary salt quenching is magnesium borate, magnesium oxide grains are formed in the long rod bolt after the primary salt quenching, so that the grain boundaries of austenite are pinned, the growth of austenite grains is suppressed, and the formation of acicular ferrite is promoted. The molten salt solution for the secondary salt quenching is aluminum silicate. When the secondary salt quenching is performed, the aluminum silicate and the borate on the surface of the long rod bolt after the primary salt quenching are combined to form a dense ceramic layer. The long rod bolt prepared by the application has high toughness and good corrosion resistance.

This invention belongs to the field of metallic materials technology and provides a method for manufacturing a 460MPa grade steel plate that can be welded without preheating in a low-temperature environment. The composition employs a low-carbon, low-manganese chemical system, with the addition of microalloying elements such as V-N, Ti, and Mo to refine the grain size. Precise control of the (Ti+V) / N ratio ensures the formation of precipitates during welding. The addition of elements such as La, Ca, and Mg improves the purity of the molten steel and the quality of the continuously cast billet, forming fine, dispersed oxide particles in the steel and enhancing the overall performance in the thickness direction of the steel plate. The manufacturing method includes smelting, continuous casting, furnace heating, rolling, online cooling, and tempering. The steel plate produced using this invention has a microstructure of acicular ferrite + tempered sorbite, with precipitates of 40-60 nm in size. The steel plate exhibits excellent low-temperature toughness, enabling preheating-free welding at -10℃, and the welded joints possess excellent mechanical properties.

A tailor-welded component, and a manufacturing method therefor and a welding wire applied thereto. The tailor-welded component comprises a welded joint. A weld seam of the welded joint comprises acicular ferrite and martensite. The acicular ferrite has an average length of not greater than 80 μm and an average diameter of not greater than 15 μm, and the volume percentage of the ferrite in the weld seam is 0.1-10%. The tailor-welded component is a hot-stamped component, the welded joint has an elongation of greater than 4%, the weld seam structure comprises the martensite and the acicular ferrite, a fracture position is located at a base material during a quasi-static tensile test, and the weld seam has a good strength and ductility.