Low-carbon bismuth-containing environment-friendly free-cutting structural steel

Abstract

The invention relates to low-carbon bismuth-containing environment-friendly free-cutting structural steel. Calculated according to percentage by weight, the structural steel contains 0.15 percent or less of C, 0.75 to 1.50 percent of Mn, 0.23 to 0.42 percent of S, 0.10 percent or less of Si, 0.11 percent or less of P, 0.05 to 0.20 percent of Bi, 0.0010 to 0.0200 percent of N and the balance of Fe and impurities; the mass percentage ratio of Mn to S is equal to 1.79 to 6.52, and the mass percentage ratio of Bi to S is equal to 0.12 to 0.87; Altot is less than or equal to 0.02 percent, and T[O] is 0.0010 to 0.0250 percent. The structural steel has cutting property superior to the cutting property of the conventional lead-free free-cutting steel with corresponding carbon content and not inferior to the cutting property of the conventional leaded free-cutting steel with corresponding carbon content and good comprehensive mechanical properties under the room temperature, and has environment-friendliness which the conventional leaded free-cutting steel with corresponding carbon content does not have, and moreover, the cost is lower.

Description

technical field [0001] The invention relates to a free-cutting structural steel, in particular to a low-carbon bismuth-containing environment-friendly free-cutting structural steel, which belongs to the technical field of metallurgy. Background technique [0002] At present, in the production and development process of "low-carbon free-cutting structural steel" in the domestic iron and steel industry and national standards, sulfur and phosphorus are usually added to steel, or sulfur-lead, sulfur-phosphorus-lead, sulfur-calcium, sulfur -Tin, sulfur-phosphorus-tin and other free-cutting elements, the existing problems are: (1) The steel types and grades of domestic low-carbon free-cutting structural steels are relatively imperfect. (2) Although lead-containing free-cutting structural steel has better cutting performance, it pollutes the environment more during production and use, and is harmful to health and poor in environmental protection. (3) Although ordinary free-cutting...

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