(1) Scrap steel is the main raw material for casting smelting. Two samples are randomly selected from each batch for chemical composition inspection. Scrap steel can be divided into high manganese steel and low manganese steel according to manganese content. Inspection according to scrap size and specification: medium waste is various steel trimming, ship plate, steel casting and various mechanical scrap with external dimension ≤ 1000 500 300 mm, thickness ≤ 6 mm and unit weight ≤ 5 kg. The small wastes include various steel trimming, ship plate, steel casting and various mechanical scrap with external dimension ≤ 1000 500 300 mm, thickness ≤ 4 mm and single weight ≤ 2 kg. The waste is scrap with thickness ≤ 4 mm and weight less than 2 kg. Scrap steel is inspected by magnifying glass to detect the following contents:
Acceptance rules of shape and size: the shape and size are regular and uniform. Oversized, overlength and overweight scrap cannot be used as raw material, and steel sheet less than 2 mm shall not be used.
No iron alloy, non-ferrous metal and other impurities shall be mixed in the scrap steel. There shall be no mud block, cement, clay sand, rubber, etc. on the surface of the scrap steel, and the oil stain on the surface of the scrap steel shall be removed. It is not allowed to have tube, vessel, inflammable and explosive materials, radioactive and toxic substances in scrap steel. Complete sets of machinery, equipment and structural parts are not allowed in scrap steel.
(2) The main function of ferrosilicon is to adjust the content of silicon in zg40mn. Its brand is fesi75a11.5-b. silicon has a high affinity with oxygen, which is usually added 10 minutes before tapping after the deoxidizer is used. The content of silicon should be between 72-80% and the content of aluminum should not be more than 1%. The control of harmful elements such as sulfur and phosphorus must be strictly controlled below 0.02%. The following contents are generally observed through a magnifying glass:
The number of pieces with a block weight of more than 20kg should not exceed 10% of the batch weight, and the fragments should not exceed 10% of the batch weight. The surface of ferrosilicon should be clean without obvious slag, sand and other inclusions.
(3) The main function of high carbon ferromanganese is to adjust the content of manganese. The material grade is femn68c7.0, and the affinity between manganese and oxygen is greater than that of iron. Ferromanganese should be put into it together with slag after the formation of thin slag. The ferromanganese adjusted in the later stage of reduction should be added 10 minutes before tapping. The chemical content of manganese should be controlled between 62-75%, and the content of sulfur and phosphorus should be strictly controlled. The content of s should not exceed 0.03%.
Observe the following contents through 10 times magnifying glass: the single weight of ferromanganese block should not be more than 40 kg. The particle size range is 30-250 mm. The surface quality shall be clean and free from impurities and foreign inclusions.
(4) Si Al Fe alloy is a kind of deoxidizer used in steel-making production. It can improve the shape of inclusions and reduce the content of gas elements in molten steel. It is an effective means to improve the quality of molten steel, reduce the cost and save aluminum. The surface quality of the alloy should be clean and free from obvious bubbles, non-metallic inclusions and other impurities. Its aluminum content is controlled at 35-55%.