Environment-friendly leadless free-cutting steel and metallurgy method thereof

Abstract

The invention relates to an environment-friendly leadless free-cutting steel which comprise the following components by weight percent: 0.04 to 0.15 % of C, 0.95 to 1.40 % of Mn, 0.04 to 0.09 % of P. 0.25 to 0.45 % of S, less than or equal to 0.03 % of Si, 0.025 to 0.25 % of Bi, 0.10 to 0.35 % of Ca, less than or equal to 0.03 % of As, less than or equal to 0.03 % of Cu, less than or equal to 0.03 % of Cr, less than or equal to 0.03 % of Ni, less than or equal to 0.03 % of Mo, less than or equal to 0.03 % of Al and the balance being Fe. A metallurgy method of the environment-friendly leadless free-cutting steel comprises smelting by using a converter or an electric furnace firstly and a refining furnace secondly, and then continuously casting or molding into blanks, wherein nano-graphite accounting for 0.008 to 0.015 % of a total weight of molten steel is added during a smelting process in the refining furnace, so that 0.008 to 0.015 % of nano-solid C is contained in the product. By adding bismuth with a melting point less than that of the lead and carbon materials with excellent lubricating effect, lubrication effect on cutting tools is relatively good during a metallic material machining process, being nontoxic and harmless as well; and the method has advantages of simple process, strong operationality and low production cost.

Description

technical field

[0001] The invention relates to a steel product, in particular to an environment-friendly lead-free free-cutting steel and a metallurgical method thereof. Background technique

[0002] With the rapid development of intelligent machining, various free-cutting steels are constantly being developed and produced in the world. Products with lower cost and more mature technology are generally recognized as sulfur-based free-cutting steels and lead-based free-cutting steels. The representative steel number of sulfur-based free-cutting steel is 1215; the representative steel number of lead-based free-cutting steel is 12L14.

[0003] The chemical composition of sulfur-based free-cutting steel 1215 and lead-based free-cutting steel 12L14 is shown in Table 1.

[0004] Table 1

[0005] steel number C mn P S Si Pb 1215 ≤0.09 0.75～1.05 0.04～0.09 0.26～0.35 ≤0.10～0.35 12L14 ≤0...