Gray cast iron and production method thereof
The invention discloses a gray cast iron and a production method thereof. The gray cast iron comprises the following chemical components in percentage by weight: 3.1-3.3% of C, 1.8-2.2% of Si, 0.5-0.8% of Mn, 0-0.04% of P, 0.05-0.1% of S, 0.1-0.4% of Cr, 0.3-0.5% of Cu, 0-0.06% of Sn, Sb less than 0.02%, and the balance amount of Fe. The gray cast iron disclosed by the invention is suitable for producing casting parts which easily shrunk, have thick walls, and have marks above HT300; according to the production method of the gray cast iron, the technical means of adding copper, chrome, antimony and tin in molten iron for alloying in the gray cast iron production process is adopted, so that molybdenum and nickel for alloying in the prior art are replaced, thereby solving the problem of high possibility of shrinkage and looseness of gray cast iron products, after the prepared gray cast iron is used for casting and forming, the casting parts have low possibility of shrinkage and looseness, have no shrinkage hole, have high yield and are low in production costs. 1. A gray cast iron, characterized in that the percentage content of each chemical component of the weight of the: C: 3.1%-3.3%, Si: 1.8%-2.2%, Mn: 0.5%-0.8%, P:0-0.04%, S: 0.05%-0.1%, Cr: 0.1%-0.4%, cu: 0.3%-0.5%, Sn:0-0.06%, Sb : <0.02%, the balance being Fe. 2. Gray cast iron of a method for the production according to Claim 1, characterized in that comprises the following steps: A. Sequentially according to the grade of the height of the level of the various iron raw materials into the furnace interior, heating to 1200 degrees centigrade by adding Mn iron, and to continue heating to 1500-1550 degrees of the molten iron to produce molten state; molten iron and slag; B. Cooling to 1450 ±10 degrees after the molten iron; C. The stokehole treatment at the same time of the water, the copper by adding bottom, Si-Ba, rare earth-ferro-silicon, ferro-chrome when adding along with liquid flow in the molten iron, the molten iron and tin and antimony out to a 1/2-2/3 along with liquid flow to the; furnace pre-processing the final molten mixture of various chemical composition in weight percentage control to:C: 3.1-3.3%, Si: 1.8-2.2%, Mn: 0.5-0.8%, P:0-0.04%, S: 0.05-0.1%, Cr: 0.1-0.4%, cu: 0.3-0.5%, Sn:0-0.06%, Sb : <0.02%, the balance being Fe. D. Casting molding. 3. Method for producing gray cast iron according to Claim 2, characterized in that the iron raw materials include Pig iron, scrap steel and re-melting material. 4. Method for producing gray cast iron according to Claim 3, characterized in that the percentage of the weight of the Pig iron 30-50%, the latter percentage is the weight of the steel products 30-50% ; supplied by the weight percentage of the charge 0-20%.