Classifications

• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
  • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
  • C21D9/525—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length for wire, for rods
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
  • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES, PROFILES OR LIKE SEMI-MANUFACTURED PRODUCTS OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
  • B21C23/00—Extruding metal; Impact extrusion
  • B21C23/02—Making uncoated products
  • B21C23/04—Making uncoated products by direct extrusion
  • B21C23/08—Making wire, rods or tubes
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D6/00—Heat treatment of ferrous alloys
  • C21D6/008—Heat treatment of ferrous alloys containing Si
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment
  • C21D8/06—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
  • C21D9/0075—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for rods of limited length
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D2211/00—Microstructure comprising significant phases
  • C21D2211/009—Pearlite

Definitions

• the disclosure relates to a graphite steel wire rod, steel wire and graphite steel having superior cutting performance and manufacturing methods thereof, and more particularly, to a sulfur-added graphite steel wire rod, steel wire and graphite steel having better cutting performance than common free-cutting steel and manufacturing methods thereof.
• free-cutting steel As a material for e.g., machine parts requiring machinability, free-cutting steel, to which machinability imparting elements such as Pb, Bi, and S are added, is commonly used.
• machinability imparting elements such as Pb, Bi, and S are added
• low melting point machinability imparting elements such as Pb and Bi are added to the steel to take advantage of the phenomenon of liquid metal embrittlement or a large amount of MnS is formed in the steel, and this free-cutting steel has superior machinability of the steel in terms of surface roughness, chip treatment, life of cutting tool during the cutting process.
• the graphite steel is a steel that contains fine graphite grains in a ferrite matrix or a ferrite-pearlite matrix, and the fine graphite grains act as crack sources to serve as chip breakers, thereby imparting good machinability.
• the graphite steel has not yet commercialized. This is because when carbon is added to the steel, cementite, which is a metastable phase, is precipitated even though the graphite is a stable phase, so precipitation of the graphite without a separate long-term heat treatment for 10 or more hours is difficult, and in the long-term heat treatment process, decarburization occurs, causing adversely effects the final product performance.
• the disclosure provides a sulfur-added graphite steel wire rod, steel wire, and graphite steel with superior machinability, and a manufacturing method thereof.
• a graphite steel wire rod includes, in percent by weight, 0.60 to 0.90% of carbon (C), 2.0 to 2.5% of silicon (Si), 0.1 to 0.6% of manganese (Mn), 0.015% or less (except 0) of phosphorus (P), 0.031 to 0.3% of sulfur (S), 0.01 to 0.05% of aluminum (Al), 0.005 to 0.02% of titanium (Ti), 0.0005 to 0.0020% of boron (B), 0.0030 to 0.0150% of nitrogen (N) and the remainder having Fe and unavoidable impurities.
• a method of manufacturing a graphite steel wire rod includes manufacturing a billet including, in percent by weight, 0.60 to 0.90% of carbon (C), 2.0 to 2.5% of silicon (Si), 0.1 to 0.6% of manganese (Mn), 0.015% or less (except 0) of phosphorus (P), 0.031 to 0.3% of sulfur (S), 0.01 to 0.05% of aluminum (Al), 0.005 to 0.02% of titanium (Ti), 0.0005 to 0.0020% of boron (B), 0.0030 to 0.0150% of nitrogen (N) and the remainder having Fe and unavoidable impurities; heating the billet; hot-rolling the heated billet to be manufactured into a wire rod; and cooling the wire rod.
• C carbon
• Si silicon
• Mn manganese
• P phosphorus
• S sulfur
• Al aluminum
• Ti titanium
• B boron
• N nitrogen
• a graphite steel wire includes, in percent by weight, 0.60 to 0.90% of carbon (C), 2.0 to 2.5% of silicon (Si), 0.1 to 0.6% of manganese (Mn), 0.015% or less (except 0) of phosphorus (P), 0.031 to 0.3% of sulfur (S), 0.01 to 0.05% of aluminum (Al), 0.005 to 0.02% of titanium (Ti), 0.0005 to 0.0020% of boron (B), 0.0030 to 0.0150% of nitrogen (N) and the remainder having Fe and unavoidable impurities.
• a graphite steel includes, in percent by weight, 0.60 to 0.90% of carbon (C), 2.0 to 2.5% of silicon (Si), 0.1 to 0.6% of manganese (Mn), 0.015% or less (except 0) of phosphorus (P), 0.031 to 0.3% of sulfur (S), 0.01 to 0.05% of aluminum (Al), 0.005 to 0.02% of titanium (Ti), 0.0005 to 0.0020% of boron (B), 0.0030 to 0.0150% of nitrogen (N) and the remainder having Fe and unavoidable impurities, wherein as a microstructure, graphite grains are distributed in a ferrite matrix, a graphitization rate is at least 95%, and a total of 5% or less of MnS inclusions and pearlite are included.
• a method of manufacturing a graphite steel includes manufacturing a wire rod including, in percent by weight, 0.60 to 0.90% of carbon (C), 2.0 to 2.5% of silicon (Si), 0.1 to 0.6% of manganese (Mn), 0.015% or less (except 0) of phosphorus (P), 0.031 to 0.3% of sulfur (S), 0.01 to 0.05% of aluminum (Al), 0.005 to 0.02% of titanium (Ti), 0.0005 to 0.0020% of boron (B), 0.0030 to 0.0150% of nitrogen (N) and the remainder having Fe and unavoidable impurities; and performing graphitization heat treatment on the manufactured wire rod.
• C carbon
• Si silicon
• Mn manganese
• P phosphorus
• S sulfur
• Al aluminum
• Ti titanium
• B boron
• N nitrogen
• a graphite steel wire rod includes, in percent by weight, 0.60 to 0.90% of carbon (C), 2.0 to 2.5% of silicon (Si), 0.1 to 0.6% of manganese (Mn), 0.015% or less (except 0) of phosphorus (P), 0.031 to 0.3% of sulfur (S), 0.01 to 0.05% of aluminum (Al), 0.005 to 0.02% of titanium (Ti), 0.0005 to 0.0020% of boron (B), 0.0030 to 0.0150% of nitrogen (N) and the remainder having Fe and unavoidable impurities.
• a graphite steel wire rod, steel wire and graphite steel with superior machinability and a manufacturing method thereof according to the disclosure will now be described in detail.
• a graphite steel wire rod includes, in percent by weight (wt%), 0.60 to 0.90% of carbon (C), 2.0 to 2.5% of silicon (Si), 0.1 to 0.6% of manganese (Mn), 0.015% or less (except 0) of phosphorus (P), 0.031 to 0.3% of sulfur (S), 0.01 to 0.05% of aluminum (Al), 0.005 to 0.02% of titanium (Ti), 0.0005 to 0.0020% of boron (B), 0.0030 to 0.0150% of nitrogen (N) and the remainder having Fe and unavoidable impurities.
• Silicon is actively added because it is a component required as a deoxidizer in manufacturing molten steel and a graphitization promoting element to precipitate the carbon as graphite by unstabilize cementite in steel.
• the silicon content is at least 2.0wt%. Otherwise, when the content is excessive, not only the effect may be saturated but also it is likely that the hardness increases due to a solid solution strengthening effect, leading to acceleration of tool wear, brittlement is caused by an increase of nonmetallic inclusions and excessive decarburization is caused during hot rolling. Accordingly, it is desirable that the silicon content has an upper limit of 2.5wt%.
• Manganese improves strength and impact properties of steel materials and contributes to machinability enhancement by combining with sulfur in steel and forming MnS inclusions.
• it is desirable that manganese is contained in at least 0.1wt%.
• the content when the content is excessive, it may interfere with graphitization, delaying graphitization completion time and may increase the strength and hardness, thereby deteriorating machinability. Accordingly, it is desirable that the manganese content has an upper limit of 0.6wt%.
• Phosphorus is an impurity unavoidably contained. Although phosphorus helps machinability by weakening grain boundaries of steel, it increases hardness of ferrite through a significant solid solution strengthening effect, reduces toughness and delayed fracture resistance of the steel and promotes occurrence of surface defects, so it is desirable to maintain the content as low as possible. It is advantageous to control the phosphorus content to be 0wt% in theory, but the phosphorus is inevitably contained in a manufacturing process. Hence, it is important to manage the upper limit, and in the disclosure, the upper limit is kept to 0.015wt%.
• Titanium is combined with nitrogen together with boron, aluminum, etc., to produce nitrides such as TiN, BN, AIN, etc., and the nitrides act as nuclei for graphite formation during isothermal heat treatment.
• nitrides such as TiN, BN, AIN, etc.
• TiN has a higher formation temperature than AIN or BN and is crystallized before austenite formation is completed, so it is uniformly distributed at the austenite grain boundaries and within the grains. Therefore, the graphite grains produced using TiN as the nucleation site are also distributed finely and uniformly.
• the titanium content has an upper limit of 0.02wt%.
• the hot-rolling the billet to be manufactured into a wire rod may include hot-rolling at a temperature range of 900 to 1150 °C.
• the reason for setting the wire rod rolling temperature into a range of 900 ⁇ 1150°C is that surface blemishes may easily occur during hot rolling or rolling may be hard because the rolling load increases at less than 900 °C, and that austenite grain size (AGS) becomes coarse at higher than 1150°C, increasing graphitization heat treatment hours after wire rod rolling.
• AGS austenite grain size
• the cooling may include cooling down to 500 °C at 0.1 ⁇ 10.0°C/s.
• Embodiments 1 to 11 satisfy the alloy composition range and manufacturing conditions of the disclosure, so that the area fraction of pearlite in the graphite steel wire rod is at least 95%, the graphitization rate is at least 98.5%, and the cutting performance is 100% as compared to lead free-cutting steel.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Manufacturing & Machinery (AREA)
• Heat Treatment Of Steel (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=85988461

Family Applications (1)

Country Status (6)

Families Citing this family (2)

Family Cites Families (12)

• 2021
  • 2021-10-12 KR KR1020210135091A patent/KR20230052013A/ko active Pending
• 2022
  • 2022-10-11 EP EP22881305.1A patent/EP4394072A4/de active Pending
  • 2022-10-11 WO PCT/KR2022/015274 patent/WO2023063678A1/ko not_active Ceased
  • 2022-10-11 US US18/700,472 patent/US20240401167A1/en active Pending
  • 2022-10-11 JP JP2024522128A patent/JP2024536913A/ja active Pending
  • 2022-10-11 CN CN202280068336.4A patent/CN118076760A/zh active Pending

Also Published As

Similar Documents

Legal Events