Preparation method of high-strength thin-wall gray iron casting

Abstract

The invention discloses a preparation method of a high-strength thin-wall gray iron casting. 3-8% of pig iron, 50-65% of waste steel and 27-42% of returns are adopted as raw materials of molten iron liquid, the process method of smelting, primary recarburization, primary inoculation, secondary recarburization, secondary inoculation, casting, in-mold inoculation and annealing is adopted, and the high-strength thin-wall gray iron casting is obtained. The high-strength thin-wall gray iron casting is prepared from chemical components in percent by mass: 2.9-3.5% of C, 1.4-2.1% of Si, 0.7-1.1% of Mn, smaller than or equal to 0.05% of P, smaller than or equal to 0.08% of S, smaller than or equal to 0.03% of Cu, 0.031-0.043% of Sn, 0.01-0.03% of RE and the balance Fe and inevitable impurities. Bymeans of the preparation method, the high-strength thin-wall gray iron casting can be prepared, the cost of the high-strength thin-wall gray iron casting is low, and the comprehensive performance issuperior to the national standard with the casting shop name being HT250.

Description

technical field [0001] The invention relates to the technical field of casting, in particular to a preparation method of high-strength thin-walled gray iron castings. Background technique [0002] Castings are metal shaped objects obtained by various casting methods. According to different casting methods, castings can be divided into ordinary sand castings, metal castings, die castings, centrifugal castings, continuous castings, investment castings, and ceramics. Castings, electroslag remelting castings, bimetallic castings, etc. Among them, ordinary sand castings are the most used, accounting for about 80% of the total casting output. [0003] In the prior art, the common way to improve the strength of thin-walled gray iron castings is to adjust the chemical composition, that is, to reduce the carbon content in the casting raw materials, increase the manganese content, and add alloying elements for alloying treatment, and the addition of alloying elements causes a decrease...

AI Technical Summary

Problems solved by technology

[0003] In the prior art, the common way to improve the strength of thin-walled gray iron castings is to adjust the chemical composition, that is, to reduce the carbon content in the casting raw materials, increase the manganese content, and add alloying elements for alloying treatment, and the addition of alloying elements causes a decrease in the cost of castings. increase; the existing technology adopts the method of conventional smelting, one-time carburization and one-time inoculation, and the obtained gray iron castings have uneven graphite distribution, long and thin parts, and thick parts, which seriously reduces the performance of cast iron

[0004] The Chinese patent with the patent application number CN201510141701.1 discloses a preparation method of gray iron castings. The ratio of raw materials used in the gray iron castings of this patent is 10-20% of pig iron, 35-45% of scrap steel, and 0.6-45% of ferrosilicon. 0.8%, carburant 1-1.3%, and the rest of the furnace charge, and prepared by smelting, one-time carburization, step-by-step inoculation with flow and casting, the obtained gray iron castings, its comprehensive performance basically meets the requirements of HT250 castings. Standard, but when the wall thickness is thin, the graphite is easily distributed unevenly and thickly, which will cause a decrease in strength, resulting in a decrease in the service life and overall performance of the casting