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CN-117488187-B - Cerium-containing austenitic free-cutting steel and preparation method thereof

CN117488187BCN 117488187 BCN117488187 BCN 117488187BCN-117488187-B

Abstract

The invention discloses cerium-containing austenitic free-cutting steel and a preparation method thereof, wherein the cerium-containing austenitic free-cutting steel comprises, by mass, 0.1-0.4% of C, 1.5-2.0% of Mn, 0.1-0.3% of Si, 6.0-8.0% of Ni, 15.0-17.0% of Cr, 0.1-0.2% of Mo, 0.1-0.5% of S, 0.001-0.3% of Ce, and the balance of Fe and unavoidable impurities. According to the invention, by reasonably adding cerium element into the austenitic free-cutting steel, the morphology, the size, the length-width ratio and the distribution of sulfides in the free-cutting stainless steel can be effectively controlled and improved, so that the free-cutting stainless steel has good cutting performance and very good mechanical property.

Inventors

  • WANG YINGHU
  • SONG LINGXI
  • SHENG ZHENDONG

Assignees

  • 成都先进金属材料产业技术研究院股份有限公司

Dates

Publication Date
20260508
Application Date
20231103

Claims (8)

  1. 1. A cerium-containing austenitic free-cutting steel is characterized by comprising, by mass, 0.32-0.4% of C, 1.5-2.0% of Mn, 0.1-0.3% of Si, 7.82-8.0% of Ni, 15.0-17.0% of Cr, 0.1-0.2% of Mo, 0.1-0.5% of S, 0.001-0.02% of Ce, and the balance of Fe and unavoidable impurities; The proportion of sulfide with the length-width ratio less than or equal to 3 in the cerium-containing austenitic free-cutting steel reaches more than 88 percent; The tensile strength of the cerium-containing austenitic free-cutting steel is more than or equal to 500MPa, the yield strength is more than or equal to 250MPa, the area shrinkage is more than or equal to 15%, the elongation after fracture is more than or equal to 10%, and the impact toughness is more than or equal to 15J.
  2. 2. The cerium-containing austenitic free-cutting steel according to claim 1, wherein the cerium-containing austenitic free-cutting steel comprises 0.001 to 0.0082% Ce by mass.
  3. 3. The cerium-containing austenitic free-cutting steel according to claim 1, wherein the cerium-containing austenitic free-cutting steel contains 0.1 to 0.3% of S by mass percent.
  4. 4. A method of producing the cerium-containing austenitic free-cutting steel according to any one of claims 1 to 3, characterized by comprising sequentially subjecting to batching, melting, casting, heat treatment to obtain the cerium-containing austenitic free-cutting steel.
  5. 5. The method according to claim 4, wherein the smelting is performed using an intermediate frequency induction furnace.
  6. 6. The method according to claim 4, wherein the smelting temperature is 1450-1650 ℃, and the tapping temperature is 1550-1650 ℃.
  7. 7. The method of claim 4, wherein performing the heat treatment comprises: Firstly, homogenizing at 1200-1250 ℃ for 3-5 hours; Then carrying out solution treatment at 1100-1200 ℃ for 1-2 hours; finally, aging treatment is carried out, wherein the temperature is 300-600 ℃ and the time is 1-5 hours.
  8. 8. The method according to claim 4, wherein before casting, the method further comprises molding sodium silicate sand, hardening the sand mold by blowing carbon dioxide, painting the inner wall of the sand mold, and drying to obtain the casting sand mold.

Description

Cerium-containing austenitic free-cutting steel and preparation method thereof Technical Field The invention relates to the technical field of metallurgy, in particular to cerium-containing austenitic free-cutting steel and a preparation method thereof. Background Free cutting steel refers to alloy steel in which a certain amount of one or more free cutting elements such as sulfur, phosphorus, lead, calcium, selenium, tellurium and the like are added to the steel to improve cutting performance. The free-cutting steel may be classified into a sulfur-based free-cutting steel, a lead-based free-cutting steel, a titanium-based free-cutting steel, a composite free-cutting steel, and the like, depending on the free-cutting elements contained therein. . The sulfur free-cutting steel is mainly applied to complex parts such as bolts, nuts, pipe joints, automobile brake parts, spring seats, dies and the like, and the complex parts need to be cut on a numerical control machine, so that the service life of a cutter is prolonged, the processing cost is reduced, the production efficiency is improved, and the steel must have good cutting performance. Sulfur in the sulfur free-cutting steel mainly exists in the form of manganese sulfide, and the manganese sulfide inclusion can be used as a stress concentration source to induce a matrix to generate a plurality of microcracks, so that the cutting resistance is reduced and the steel is easy to break during turning. Manganese sulfide in steel casting structures is classified by Sims and Dahle at the earliest, and is classified into three types according to the shape and distribution of manganese sulfide, namely, a type I spherical composite inclusion which is randomly distributed and exists in steel which is not deoxidized by aluminum, a type II short rod which is distributed in a chain or net shape along a grain boundary and exists in steel deoxidized by a small amount of aluminum, a type III block which is irregularly distributed and exists in steel which is high in aluminum addition and has residual aluminum, and a type IV dendritic sulfide is added by researchers later. Oikawa et al studied the effect of alloying elements in free-cutting steels on the morphology of manganese sulfide and classified manganese sulfide as [1] spherical (class I), formed by devitrification, [2] short rods or dendrites (class II), formed by eutectic reactions, and [3] irregular shapes (class III), formed by pseudo-eutectic reactions. The size, morphology and distribution of the manganese sulfide in the sulfur-containing free-cutting steel have remarkable influence on the mechanical properties of the steel, so that sulfide inclusions with small spherical or spindle-shaped aspect ratio are expected to be obtained in production in order to obtain the optimal cutting performance, and the slender strip-shaped manganese sulfide with the aspect ratio exceeding 4:1 not only damages the continuity of a matrix, but also can cause cutting scraps to adhere to reduce the surface quality of a workpiece. However, the prior art fails to provide effective control of sulfide morphology in high sulfur austenitic free cutting stainless steels. Disclosure of Invention The invention mainly aims to provide cerium-containing austenitic free-cutting steel and a preparation method thereof, so as to solve the problem that sulfide forms in high-sulfur austenitic free-cutting stainless steel cannot be effectively controlled in the prior art. According to one aspect of the present invention, there is provided a cerium-containing austenitic free-cutting steel comprising, by mass, 0.1 to 0.4% of C, 1.5 to 2.0% of Mn, 0.1 to 0.3% of Si, 6.0 to 8.0% of Ni, 15.0 to 17.0% of Cr, 0.1 to 0.2% of Mo, 0.1 to 0.5% of S, 0.001 to 0.3% of Ce, and the balance of Fe and unavoidable impurities. According to one embodiment of the invention, the proportion of sulfide with the length-width ratio less than or equal to 3 in the cerium-containing austenitic free-cutting steel is more than 88%. According to one embodiment of the invention, the tensile strength of the cerium-containing austenitic free-cutting steel is more than or equal to 500MPa, the yield strength is more than or equal to 250MPa, the area reduction rate is more than or equal to 15%, the elongation after fracture is more than or equal to 10%, and the impact toughness is more than or equal to 15J. According to one embodiment of the invention, the cerium-containing austenitic free-cutting steel comprises 0.001-0.02% of Ce in percentage by mass. According to one embodiment of the invention, the cerium-containing austenitic free-cutting steel comprises 0.1-0.3% of S by mass percent. According to another aspect of the present invention, there is provided a method for preparing the cerium-containing austenitic free-cutting steel as described above, comprising sequentially subjecting to batching, melting, casting, and heat treatment to obtain the cerium-containing austenitic free-cutting