Water-explosion-free manufacturing method for super duplex stainless steel valve body casting for circulating water pump

Abstract

The invention discloses a water-explosion-free manufacturing method for a super duplex stainless steel valve body casting for a circulating water pump. The water-explosion-free manufacturing method comprises the steps of: step 1, prefabrication of a molding sand casting mold; step 2, smelting and pouring; step 3, box opening and first heat treatment; step 4, cleaning of molding sands; and step 5, secondary heat treatment. By using the water-explosion-free manufacturing method disclosed by the invention, it can be guaranteed that the production process is safe and reliable, and molten steel mold filling can be stable and sufficient through the technological design of a pouring system, so that sequential solidification is achieved, the feeding effect of a riser is good, the structure is compact, the casting defects such as shrinkage porosity and air holes are effectively avoided, and the casting yield is increased; the brittle phase can be controlled to be separated out as little as possible through first heat treatment, and the cracking and scrapping phenomena caused by brittle phase separation in the casting production process can be avoided; and secondary heat treatment adopts a segmented heating mode, so that the yield of casting products is increased, the risk of water explosion sputtering of a molding material can be effectively avoided at the same time, the content of the ferrite alpha phase in the structure meets the standard, safe production is realized at the same time, and the water-explosion-free manufacturing method has important production guiding significance.

Description

technical field [0001] The invention belongs to the technical field of casting of super duplex stainless steel, and relates to a water explosion-free preparation method of a super duplex stainless steel valve body casting for a circulating water pump. Background technique [0002] Duplex stainless steel combines the advantages of ferrite and austenite, has high strength, excellent toughness, weldability, resistance to intergranular corrosion and chloride stress corrosion resistance, and is widely used in pulp and paper industry, chemical Industry, food and beverage industry, transportation industry, offshore oil and gas industry and other fields; super duplex stainless steel is the third generation of duplex stainless steel, which is characterized by ultra-low carbon, high chromium, high nickel, high molybdenum and high nitrogen, in production In the stage of 600-850°C, the brittle second phase represented by the σ phase is easily produced, and the ferrite is brittlely decom...

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Problems solved by technology

[0002] Duplex stainless steel combines the advantages of ferrite and austenite, has high strength, excellent toughness, weldability, resistance to intergranular corrosion and chloride stress corrosion resistance, and is widely used in pulp and paper industry, chemical Industry, food and beverage industry, transportation industry, offshore oil and gas industry and other fields; super duplex stainless steel is the third generation of duplex stainless steel, which is characterized by ultra-low carbon, high chromium, high nickel, high molybdenum and high nitrogen, in production In the stage of 600-850°C, the brittle second phase represented by the σ phase is easily produced, and the ferrite is brittlely decomposed at the stage of 400-500°C. The boxing scheme is avoided, but this method cannot remove the modeling materials attached to the surface of the complex irregular surface structure, such as phenolic resin sand, chilled iron, etc., and the cooling medium water is vaporized instantly when it contacts the high-temperature casting when the casting is solid-solution and heat-preserved. The material attached to the surface is not consistent with the cooling shrinkage of the casting. Water explosion will occur at the moment of entering the water. Strong sputtering and high-speed jetting of molding materials will endanger the on-site operators and equipment of heat treatment, and there is a greater safety risk.

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