Production technique of lead treated steel

Abstract

The invention belongs to the field of metallurgy, and provides a production process of free-cutting steel containing lead, comprising a smelting process, a lead adding process and a continuous casting process; in the smelting process, the baking temperature of molten steel tundish is 1000-1150 DEG C; the sulfur content in the molten steel is 0.28-0.33%; the manganese content in the molten steel is 1.2-1.25%; in the lead adding process, inert gas is blown through the bottom of the steel ladle so as to carry out the mixing; lead grains are uniformly added into the steel ladle from above the steel ladle at low speed; the inert gas is blown on the lead-added conduit; in the continuous casting process, the pulling speed of the continuous casting ingot is 1.8-2.4m / min; the continuous casting adopts a method of full-protection casting; a long-gate argon-sealed protection method is adopted from the steel ladle to the tundish; an immersion typed gate protection casting method is used from the tundish to a crystallizer; the over-heat temperature of the tundish of the first furnace for continuous cast starting is 35-45 DEG C; the over-heat temperature of the tundish of normal furnace is 25-35 DEG C. The production process has the advantages of low production cost, easy control of operation and the like; the production method has successful continuous casting pouring and good surface quality of the plate slab.

Description

technical field [0001] The invention belongs to the field of metallurgy, and relates to a steel production process, in particular to a lead-containing free-cutting steel production process. Background technique [0002] Free-cutting steel is widely used in many fields such as household appliances and instrumentation industries due to its good machinability, high surface finish and high dimensional accuracy. Lead-containing free-cutting steel is developed on the basis of sulfur-based free-cutting steel , generally used in the manufacture of high-strength free-cutting steel required for the automotive industry. [0003] During the cutting process of lead-containing free-cutting steel, the lead particles mainly act as lubrication and embrittlement to improve the cutting performance of the steel, thereby significantly reducing the cutting resistance and reducing tool wear. In addition, lead is also easy to curl and embrittle chips, improve chip breaking characteristics, and imp...

AI Technical Summary

Problems solved by technology

[0004] The proportion of lead is large and the toxicity is also large. Some problems will occur if the process of adding lead is improper, such as: lead volatilization causes environmental pollution and endangers personal health; the yield of lead is low and unstable; Uneven distribution in the medium; due to the large proportion of lead, it is easy to segregate in the steel, and because of its low melting point, it is easy to cause the accumulation of lead during the solidification of molten steel, resulting in solidification segregation, etc.

[0005] In the existing production process of lead-containing free-cutting steel, how to effectively control the oxygen content of molten steel, ensure the uniformity of lead in molten steel, how to solve the surface quality of the slab, and the environmental sanitation problem have not been well resolved.