Low carbon high sulfur phosphorus easy cutting steel

Abstract

The cutting steel with low content of C and high contents of S and P contains proportionally C, Si, Mn, P, S, N, Ca, Mg, Al, O, and Fe. It is prepared through smelting in electric furnace, conticasting and tandem rolling to become wire and rod. It has high cutting and mechanical performance.

Description

technical field [0001] The invention relates to the composition design of free-cutting structural steel in the metallurgical industry, in particular to sulfur-based free-cutting structural steel. Background technique [0002] Structural steel is a common type of steel. In recent years, with the rapid development of machinery and equipment manufacturing industries (increased degree of automation in machining, wide application of CNC machine tools), the ease of cutting of structural steel materials (reducing the machining of parts cost, improve production efficiency) has become the pursuit of steel users (the cost of cutting and processing accounts for about 50% of the total cost of parts, and the price competition of home appliances, office equipment, automobiles, IT and other industries where parts are applied is becoming increasingly fierce, and the cost of free-cutting steel The proportion of consumption in the total steel demand is increasing year by year. For example, in...

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Problems solved by technology

The advantages of sulfur-based free-cutting steel are: no lead pollution, and it is an environmentally friendly free-cutting steel; the disadvantage is: the free-cutting performance is lower than that of lead-based free-cutting steel

The final performance of the material depends on the composition design, smelting process, and processing technology), and the sulfur-based free-cutting steel that achieves the cutting performance of lead-based free-cutting structural steel has not yet been industrialized (the domestic smelting method and inclusion control of free-cutting steel , hot-working plasticity and rolling process research are few, and the key technology of free-cutting steel is immature, such as continuous casting and continuous casting of low-carbon and high-sulfur free-cutting steel with high production efficiency, short delivery time and low production cost Continuous rolling is still a restricted area), resulting in the situation that the material is basically dependent on imports (imported materials are basically SUM24L, 12L14 and other lead-based free-cutting steels)

From a foreign point of view, some sulfur-based free-cutting steels with better cutting performance have been included in the standard, such as the American brand 1211 steel (C≤0.13%, Mn=0.60-0.90%, P=0.07-0.12%, S=0.10- 0.15%), 1213 steel (C≤0.13%, Mn=0.70~1.00%, P=0.07~0.12%, S=0.24~0.33%), the latest research progress has also published many patents (such as Japan’s Sumitomo Corporation in The patent applied by China: a low-carbon sulfur free-cutting steel, application number 03103453.5), however, these patents included in the production standard or published have the following problems: first, the hot brittleness of high-sulfur phosphorus steel is difficult to control, This leads to difficulties in production; second, most of the published patents are produced by laboratory methods, such as intermediate frequency furnace or small electric furnace smelting, pouring steel ingots, and forging bars. Such processes cannot simulate continuous casting and rolling Therefore, it is difficult to transform its research results into industrial production; third, its cutting performance stability is poor, and it is necessary to truly replace lead-based free-cutting steel (lead-based free-cutting steel with good cutting performance, when parts are processed, CNC machine tool spindles The rotation speed can reach 4000r / min, taking the free-cutting steel bar of φ20mm as an example, the linear speed of the bar surface can reach 251.327m / min), which does not yet have the capacity of industrial production

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