GST high strength toughness seawater corrosion resistant iron casting and its production method

Abstract

The invention relates to a GST high strength toughness sea water corrosion resistant iron casting which is a low nickel chromium alloy iron casting, comprising a seawater or sewage waterborne engineering gate, a gate slot embedded part, parts such as trash screens, a seawater or sewage pump housing, an impeller, conveying pipelines, a pipe fitting, a valve and the like. The tensile strength of the iron casting is greater than or equal to 450MPa, its elongation percentage is greater than or equal to 5% and its corrosion speed in seawater is less than or equal to 0.10mm / a; The mass percent of iron casting alloy elements is as follows: 2.80-3.60 of C, 1.60-2.60% of Si, 0.40-1.2% of Mn, 0.80-1.8% of Cr, 0.8-3.2% of Ni, 0.6-1.5% of Cu and the balance being Fe. According to the invention, technologies of intermediate frequency induction furnace melting, compound reinforced inoculation and lost foam casting are adopted to obtain the GST high strength toughness seawater corrosion resistant iron casting with uniform chemical component and microstructure as well as excellent mechanical properties.

Description

technical field [0001] The invention relates to a GST high-strength toughness seawater corrosion-resistant cast iron and a production method thereof, belonging to the field of production and manufacture of corrosion-resistant engineering materials. Background technique [0002] Seawater hydraulic projects, seawater desalination projects, coastal thermal power projects, coastal nuclear power projects, sewage treatment projects, etc. need to use a large number of corrosion-resistant alloy cast iron materials, such as gates, door slot embedded parts, and trash racks of seawater or sewage hydraulic projects Components such as seawater or sewage pump shells, impellers, conveying pipes, fittings, valves, etc. At present, the most commonly used corrosion-resistant cast irons in these projects are low-NiGr alloy cast irons, simple alloyed cast irons, etc. The disadvantages of these materials are: 1) The tensile strength is low, generally σ b At about 200MPa, elongation δ 5 0; 2) T...

AI Technical Summary

Problems solved by technology

At present, the most commonly used corrosion-resistant cast irons in these projects are low-NiGr alloy cast irons, simple alloyed cast irons, etc. The disadvantages of these materials are: 1) The tensile strength is low, generally σ b At about 200MPa, elongation δ 5 0; 2) The corrosion rate in seawater is relatively high, and the annual corrosion rate is ≥0.138mm / a; 3) The production process generally adopts cupola melting and sand casting. Due to the inherent shortcomings of this casting process, there are alloys in the melting process High element burning rate, low recovery rate, serious environmental pollution, segregation of alloy composition and difficult to control accurately, resulting in uneven corrosion resistance of castings; at the same time, castings have serious defects such as pores, sand holes, cracks, shrinkage porosity, and sand sticking. Increased product surface treatment and machining costs, affecting product installation and use; due to the poor mechanical properties of this type of material, on the one hand, it limits the engineering application of this type of material, and also leaves hidden dangers for these projects related to the national economy and people's livelihood

If materials such as navy brass, high-nickel austenitic corrosion-resistant cast iron, 304 stainless steel, and 316L stainless steel are used, although the corrosion resistance is high, the high cost limits the popularization and application of such materials

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