3results about How to "Reduce grain size" patented technology

A method for manufacturing a high-strength steel sheet having a tensile strength of more than 1100 MPa and a yield strength of more than 700 MPa, a uniform elongation UE of at least 8.0% and a total elongation of at least 10%, made of a steel containing in percent by weight: 0.1% ≤ C ≤ 0.25%, 4.5% ≤ Mn ≤ 10%, 1% ≤ Si ≤ 3%, 0.03% ≤ Al ≤ 2.5% , the remainder being Fe and impurities resulting from the smelting, the composition being such that CMnIndex = Cx(1 + Mn / 3.5) ≤ 0.6, the method comprising the steps of annealing a rolled sheet made of said steel by soaking it at an annealing temperature TA higher than the Ac1 transformation point of the steel but less than 1000°C, cooling the annealed sheet to a quenching temperature QT between 190°C and 80°C at a cooling speed sufficient to obtain a structure just after cooling containing martensite and retained austenite, maintaining the steel sheet at an overaging temperature PT between 350°C and 500°C for an overaging time Pt of more than 5 s cooling the sheet down to the ambient temperature. Sheet obtained.

This invention provides a method for producing ML40Cr hot-rolled wire rod, comprising the following steps: (a) heating the billet; (b) rough rolling, pre-finish rolling, and finish rolling the product from step (a) to form coils into wire; (c) controlling the temperature of the wire using a STEM air-cooled line and closing the insulation cover for heat preservation; (d) coiling the product from step (c) and passing it through an insulation corridor for further heat preservation, wherein the temperature of the coiled product entering the insulation corridor is controlled at 745–755°C, the temperature after passing through the insulation corridor is controlled at 200–300°C, and the time spent passing through the insulation corridor is controlled at 100–105 min; (e) finishing the ends of the product after passing through the insulation corridor and then packaging it. Reducing the pearlite clusters and grains in the product's metallographic structure helps improve its uniformity and thus enhances the product's performance.